[PATCHv10,ovs,12/15] datapath: Add support for unique flow identifiers.

Previously, flows were manipulated by userspace specifying a full,
unmasked flow key. This adds significant burden onto flow
serialization/deserialization, particularly when dumping flows.

This patch adds an alternative way to refer to flows using a
variable-length "unique flow identifier" (UFID). At flow setup time,
userspace may specify a UFID for a flow, which is stored with the flow
and inserted into a separate table for lookup, in addition to the
standard flow table. Flows created using a UFID must be fetched or
deleted using the UFID.

All flow dump operations may now be made more terse with OVS_UFID_F_*
flags. For example, the OVS_UFID_F_OMIT_KEY flag allows responses to
omit the flow key from a datapath operation if the flow has a
corresponding UFID. This significantly reduces the time spent assembling
and transacting netlink messages. With all OVS_UFID_F_OMIT_* flags
enabled, the datapath only returns the UFID and statistics for each flow
during flow dump, increasing ovs-vswitchd revalidator performance by up
to 50%.

Signed-off-by: Joe Stringer <joestringer@nicira.com>
CC: Pravin B Shelar <pshelar@nicira.com>
CC: netdev@vger.kernel.org
---
v10: Ignore flow_key in requests if UFID is specified.
     Only allow UFID flows to be indexed by UFID.
     Only allow non-UFID flows to be indexed by unmasked flow key.
     Unite the unmasked_key and ufid+ufid_hash in 'struct sw_flow'.
     Don't periodically rehash the UFID table.
     Resize the UFID table independently from the flow table.
     Modify table_destroy() to iterate once and delete from both tables.
     Fix UFID memory leak in flow_free().
     Remove kernel-only UFIDs for non-UFID cases.
     Rename "OVS_UFID_F_SKIP_*" -> "OVS_UFID_F_OMIT_*"
     Update documentation.
     Rebase.
v9: No change.
v8: Rename UID -> UFID "unique flow identifier".
    Fix null dereference when adding flow without uid or mask.
    If UFID and not match are specified, and lookup fails, return ENOENT.
    Rebase.
v7: Remove OVS_DP_F_INDEX_BY_UID.
    Rework UID serialisation for variable-length UID.
    Log error if uid not specified and OVS_UID_F_SKIP_KEY is set.
    Rebase against "probe" logging changes.
v6: Fix documentation for supporting UIDs between 32-128 bits.
    Minor style fixes.
    Rebase.
v5: No change.
v4: Fix memory leaks.
    Log when triggering the older userspace issue above.
v3: Initial post.
---
 datapath/README.md                                |   13 ++
 datapath/datapath.c                               |  248 +++++++++++++++------
 datapath/flow.h                                   |   20 +-
 datapath/flow_netlink.c                           |   35 +++
 datapath/flow_netlink.h                           |    1 +
 datapath/flow_table.c                             |  214 ++++++++++++++----
 datapath/flow_table.h                             |    8 +
 datapath/linux/compat/include/linux/openvswitch.h |   30 +++
 8 files changed, 453 insertions(+), 116 deletions(-)

On Thu, Nov 13, 2014 at 11:17 AM, Joe Stringer <joestringer@nicira.com> wrote:
> Previously, flows were manipulated by userspace specifying a full,
> unmasked flow key. This adds significant burden onto flow
> serialization/deserialization, particularly when dumping flows.
>
> This patch adds an alternative way to refer to flows using a
> variable-length "unique flow identifier" (UFID). At flow setup time,
> userspace may specify a UFID for a flow, which is stored with the flow
> and inserted into a separate table for lookup, in addition to the
> standard flow table. Flows created using a UFID must be fetched or
> deleted using the UFID.
>
> All flow dump operations may now be made more terse with OVS_UFID_F_*
> flags. For example, the OVS_UFID_F_OMIT_KEY flag allows responses to
> omit the flow key from a datapath operation if the flow has a
> corresponding UFID. This significantly reduces the time spent assembling
> and transacting netlink messages. With all OVS_UFID_F_OMIT_* flags
> enabled, the datapath only returns the UFID and statistics for each flow
> during flow dump, increasing ovs-vswitchd revalidator performance by up
> to 50%.
>
> Signed-off-by: Joe Stringer <joestringer@nicira.com>
> CC: Pravin B Shelar <pshelar@nicira.com>
> CC: netdev@vger.kernel.org
> ---
> v10: Ignore flow_key in requests if UFID is specified.
>      Only allow UFID flows to be indexed by UFID.
>      Only allow non-UFID flows to be indexed by unmasked flow key.
>      Unite the unmasked_key and ufid+ufid_hash in 'struct sw_flow'.
>      Don't periodically rehash the UFID table.
>      Resize the UFID table independently from the flow table.
>      Modify table_destroy() to iterate once and delete from both tables.
>      Fix UFID memory leak in flow_free().
>      Remove kernel-only UFIDs for non-UFID cases.
>      Rename "OVS_UFID_F_SKIP_*" -> "OVS_UFID_F_OMIT_*"
>      Update documentation.
>      Rebase.
> v9: No change.
> v8: Rename UID -> UFID "unique flow identifier".
>     Fix null dereference when adding flow without uid or mask.
>     If UFID and not match are specified, and lookup fails, return ENOENT.
>     Rebase.
> v7: Remove OVS_DP_F_INDEX_BY_UID.
>     Rework UID serialisation for variable-length UID.
>     Log error if uid not specified and OVS_UID_F_SKIP_KEY is set.
>     Rebase against "probe" logging changes.
> v6: Fix documentation for supporting UIDs between 32-128 bits.
>     Minor style fixes.
>     Rebase.
> v5: No change.
> v4: Fix memory leaks.
>     Log when triggering the older userspace issue above.
> v3: Initial post.
> ---
>  datapath/README.md                                |   13 ++
>  datapath/datapath.c                               |  248 +++++++++++++++------
>  datapath/flow.h                                   |   20 +-
>  datapath/flow_netlink.c                           |   35 +++
>  datapath/flow_netlink.h                           |    1 +
>  datapath/flow_table.c                             |  214 ++++++++++++++----
>  datapath/flow_table.h                             |    8 +
>  datapath/linux/compat/include/linux/openvswitch.h |   30 +++
>  8 files changed, 453 insertions(+), 116 deletions(-)
>
> diff --git a/datapath/README.md b/datapath/README.md
> index a8effa3..9c03a2b 100644
> --- a/datapath/README.md
> +++ b/datapath/README.md
> @@ -131,6 +131,19 @@ performs best-effort detection of overlapping wildcarded flows and may reject
>  some but not all of them. However, this behavior may change in future versions.
>
>
> +Unique flow identifiers
> +-----------------------
> +
> +An alternative to using the original match portion of a key as the handle for
> +flow identification is a unique flow identifier, or "UFID". UFIDs are optional
> +for both the kernel and user space program.
> +
> +User space programs that support UFID are expected to provide it during flow
> +setup in addition to the flow, then refer to the flow using the UFID for all
> +future operations. The kernel is not required to index flows by the original
> +flow key if a UFID is specified.
> +
> +
>  Basic rule for evolving flow keys
>  ---------------------------------
>
> diff --git a/datapath/datapath.c b/datapath/datapath.c
> index a898584..c14d834 100644
> --- a/datapath/datapath.c
> +++ b/datapath/datapath.c
> @@ -671,11 +671,18 @@ static void get_dp_stats(const struct datapath *dp, struct ovs_dp_stats *stats,
>         }
>  }
>
> -static size_t ovs_flow_cmd_msg_size(const struct sw_flow_actions *acts)
> +static size_t ovs_flow_cmd_msg_size(const struct sw_flow_actions *acts,
> +                                   const struct sw_flow_id *sfid)
>  {
> +       size_t sfid_len = 0;
> +
> +       if (sfid && sfid->ufid_len)
> +               sfid_len = nla_total_size(sfid->ufid_len);
> +
>         return NLMSG_ALIGN(sizeof(struct ovs_header))
>                 + nla_total_size(ovs_key_attr_size()) /* OVS_FLOW_ATTR_KEY */
>                 + nla_total_size(ovs_key_attr_size()) /* OVS_FLOW_ATTR_MASK */
> +               + sfid_len /* OVS_FLOW_ATTR_UFID */
>                 + nla_total_size(sizeof(struct ovs_flow_stats)) /* OVS_FLOW_ATTR_STATS */
>                 + nla_total_size(1) /* OVS_FLOW_ATTR_TCP_FLAGS */
>                 + nla_total_size(8) /* OVS_FLOW_ATTR_USED */
> @@ -684,33 +691,43 @@ static size_t ovs_flow_cmd_msg_size(const struct sw_flow_actions *acts)
>
>  /* Called with ovs_mutex or RCU read lock. */
>  static int ovs_flow_cmd_fill_match(const struct sw_flow *flow,
> -                                  struct sk_buff *skb)
> +                                  struct sk_buff *skb, u32 ufid_flags)
>  {
>         struct nlattr *nla;
>         int err;
>
> -       /* Fill flow key. */
> -       nla = nla_nest_start(skb, OVS_FLOW_ATTR_KEY);
> -       if (!nla)
> -               return -EMSGSIZE;
> -
> -       err = ovs_nla_put_flow(&flow->unmasked_key, &flow->unmasked_key, skb,
> -                              false);
> -       if (err)
> -               return err;
> -
> -       nla_nest_end(skb, nla);
> +       /* Fill flow key. If userspace didn't specify a UFID, then ignore the
> +        * OMIT_KEY flag. */
> +       if (!(ufid_flags & OVS_UFID_F_OMIT_KEY) ||
> +           !flow->index_by_ufid) {

I am not sure about this check, userspace needs to send atleast ufid
or the unmasked key as id for flow. otherwise we shld flag error. Here
we can serialize flow->key.
There could be another function which takes care of flow-id
serialization where we serialize use ufid or unmasked key as flow id.
Lets group ufid and unmasked key together rather than masked key and
unmasked key which are not related.

> +               nla = nla_nest_start(skb, OVS_FLOW_ATTR_KEY);
> +               if (!nla)
> +                       return -EMSGSIZE;
> +
> +               if (flow->index_by_ufid)
> +                       err = ovs_nla_put_flow(&flow->mask->key, &flow->key,
> +                                              skb, false);
> +               else
> +                       err = ovs_nla_put_flow(&flow->index.unmasked_key,
> +                                              &flow->index.unmasked_key, skb,
> +                                              false);
> +               if (err)
> +                       return err;
> +               nla_nest_end(skb, nla);
> +       }
>
>         /* Fill flow mask. */
> -       nla = nla_nest_start(skb, OVS_FLOW_ATTR_MASK);
> -       if (!nla)
> -               return -EMSGSIZE;
> +       if (!(ufid_flags & OVS_UFID_F_OMIT_MASK)) {
> +               nla = nla_nest_start(skb, OVS_FLOW_ATTR_MASK);
> +               if (!nla)
> +                       return -EMSGSIZE;
>
> -       err = ovs_nla_put_flow(&flow->key, &flow->mask->key, skb, true);
> -       if (err)
> -               return err;
> +               err = ovs_nla_put_flow(&flow->key, &flow->mask->key, skb, true);
> +               if (err)
> +                       return err;
> +               nla_nest_end(skb, nla);
> +       }
>
> -       nla_nest_end(skb, nla);
>         return 0;
>  }
>
> @@ -740,6 +757,32 @@ static int ovs_flow_cmd_fill_stats(const struct sw_flow *flow,
>  }
>
>  /* Called with ovs_mutex or RCU read lock. */
> +static int ovs_flow_cmd_fill_ufid(const struct sw_flow *flow,
> +                                 struct sk_buff *skb)
> +{
> +       struct nlattr *start;
> +       const struct sw_flow_id *sfid;
> +
> +       if (!flow->index_by_ufid)
> +               return 0;
> +
> +       sfid = &flow->index.ufid;
> +       start = nla_nest_start(skb, OVS_FLOW_ATTR_UFID);
> +       if (start) {
> +               int err;
> +
> +               err = nla_put(skb, OVS_UFID_ATTR_ID, sfid->ufid_len,
> +                             sfid->ufid);
> +               if (err)
> +                       return err;
> +               nla_nest_end(skb, start);
> +       } else
> +               return -EMSGSIZE;
> +
> +       return 0;
> +}
> +

Can you change this function according to comments above?

> +/* Called with ovs_mutex or RCU read lock. */
>  static int ovs_flow_cmd_fill_actions(const struct sw_flow *flow,
>                                      struct sk_buff *skb, int skb_orig_len)
>  {
> @@ -782,7 +825,7 @@ static int ovs_flow_cmd_fill_actions(const struct sw_flow *flow,
>  /* Called with ovs_mutex or RCU read lock. */
>  static int ovs_flow_cmd_fill_info(const struct sw_flow *flow, int dp_ifindex,
>                                   struct sk_buff *skb, u32 portid,
> -                                 u32 seq, u32 flags, u8 cmd)
> +                                 u32 seq, u32 flags, u8 cmd, u32 ufid_flags)
>  {
>         const int skb_orig_len = skb->len;
>         struct ovs_header *ovs_header;
> @@ -795,18 +838,24 @@ static int ovs_flow_cmd_fill_info(const struct sw_flow *flow, int dp_ifindex,
>
>         ovs_header->dp_ifindex = dp_ifindex;
>
> -       err = ovs_flow_cmd_fill_match(flow, skb);
> +       err = ovs_flow_cmd_fill_match(flow, skb, ufid_flags);
>         if (err)
>                 goto error;
>
> -       err = ovs_flow_cmd_fill_stats(flow, skb);
> +       err = ovs_flow_cmd_fill_ufid(flow, skb);
>         if (err)
>                 goto error;

Flow ID should go first in the netlink msg.

 >
> -       err = ovs_flow_cmd_fill_actions(flow, skb, skb_orig_len);
> +       err = ovs_flow_cmd_fill_stats(flow, skb);
>         if (err)
>                 goto error;
>
> +       if (!(ufid_flags & OVS_UFID_F_OMIT_ACTIONS)) {
> +               err = ovs_flow_cmd_fill_actions(flow, skb, skb_orig_len);
> +               if (err)
> +                       goto error;
> +       }
> +
>         return genlmsg_end(skb, ovs_header);
>
>  error:
> @@ -816,6 +865,7 @@ error:
>
>  /* May not be called with RCU read lock. */
>  static struct sk_buff *ovs_flow_cmd_alloc_info(const struct sw_flow_actions *acts,
> +                                              const struct sw_flow_id *sfid,
>                                                struct genl_info *info,
>                                                bool always)
>  {
> @@ -825,30 +875,36 @@ static struct sk_buff *ovs_flow_cmd_alloc_info(const struct sw_flow_actions *act
>                                         GROUP_ID(&ovs_dp_flow_multicast_group)))
>                 return NULL;
>
> -       skb = genlmsg_new_unicast(ovs_flow_cmd_msg_size(acts), info, GFP_KERNEL);
> +       skb = genlmsg_new_unicast(ovs_flow_cmd_msg_size(acts, sfid), info,
> +                                 GFP_KERNEL);
>         if (!skb)
>                 return ERR_PTR(-ENOMEM);
>
>         return skb;
>  }
>
> +static const struct sw_flow_id *flow_get_ufid(const struct sw_flow *flow)
> +{
> +       return flow->index_by_ufid ? &flow->index.ufid : NULL;
> +}
> +
>  /* Called with ovs_mutex. */
>  static struct sk_buff *ovs_flow_cmd_build_info(const struct sw_flow *flow,
>                                                int dp_ifindex,
>                                                struct genl_info *info, u8 cmd,
> -                                              bool always)
> +                                              bool always, u32 ufid_flags)
>  {
>         struct sk_buff *skb;
>         int retval;
>
> -       skb = ovs_flow_cmd_alloc_info(ovsl_dereference(flow->sf_acts), info,
> -                                     always);
> +       skb = ovs_flow_cmd_alloc_info(ovsl_dereference(flow->sf_acts),
> +                                     flow_get_ufid(flow), info, always);
>         if (IS_ERR_OR_NULL(skb))
>                 return skb;
>
>         retval = ovs_flow_cmd_fill_info(flow, dp_ifindex, skb,
>                                         info->snd_portid, info->snd_seq, 0,
> -                                       cmd);
> +                                       cmd, ufid_flags);
>         BUG_ON(retval < 0);
>         return skb;
>  }
> @@ -863,6 +919,8 @@ static int ovs_flow_cmd_new(struct sk_buff *skb, struct genl_info *info)
>         struct datapath *dp;
>         struct sw_flow_actions *acts;
>         struct sw_flow_match match;
> +       struct sw_flow_id sfid;
> +       u32 ufid_flags;
>         int error;
>         bool log = !a[OVS_FLOW_ATTR_PROBE];
>
> @@ -887,13 +945,20 @@ static int ovs_flow_cmd_new(struct sk_buff *skb, struct genl_info *info)
>         }
>
>         /* Extract key. */
> -       ovs_match_init(&match, &new_flow->unmasked_key, &mask);
> +       ovs_match_init(&match, &new_flow->index.unmasked_key, &mask);
>         error = ovs_nla_get_match(&match, a[OVS_FLOW_ATTR_KEY],
>                                   a[OVS_FLOW_ATTR_MASK], log);
>         if (error)
>                 goto err_kfree_flow;
>
> -       ovs_flow_mask_key(&new_flow->key, &new_flow->unmasked_key, &mask);
> +       ovs_flow_mask_key(&new_flow->key, &new_flow->index.unmasked_key, &mask);
> +
> +       /* Extract ufid. */
> +       error = ovs_nla_get_ufid(a[OVS_FLOW_ATTR_UFID], &sfid, &ufid_flags);
> +       if (!error)
> +               error = ovs_flow_ufid(new_flow, &sfid);
> +       if (error)
> +               goto err_kfree_flow;
>
>         /* Validate actions. */
>         error = ovs_nla_copy_actions(a[OVS_FLOW_ATTR_ACTIONS], &new_flow->key,
> @@ -903,7 +968,7 @@ static int ovs_flow_cmd_new(struct sk_buff *skb, struct genl_info *info)
>                 goto err_kfree_flow;
>         }
>
> -       reply = ovs_flow_cmd_alloc_info(acts, info, false);
> +       reply = ovs_flow_cmd_alloc_info(acts, &sfid, info, false);
>         if (IS_ERR(reply)) {
>                 error = PTR_ERR(reply);
>                 goto err_kfree_acts;
> @@ -915,8 +980,9 @@ static int ovs_flow_cmd_new(struct sk_buff *skb, struct genl_info *info)
>                 error = -ENODEV;
>                 goto err_unlock_ovs;
>         }
> +
>         /* Check if this is a duplicate flow */
> -       flow = ovs_flow_tbl_lookup(&dp->table, &new_flow->unmasked_key);
> +       flow = ovs_flow_tbl_lookup(&dp->table, &new_flow->key);

Need to check for ufid table to find duplicate ufid entry here.

>         if (likely(!flow)) {
>                 rcu_assign_pointer(new_flow->sf_acts, acts);
>
> @@ -932,7 +998,8 @@ static int ovs_flow_cmd_new(struct sk_buff *skb, struct genl_info *info)
>                                                        ovs_header->dp_ifindex,
>                                                        reply, info->snd_portid,
>                                                        info->snd_seq, 0,
> -                                                      OVS_FLOW_CMD_NEW);
> +                                                      OVS_FLOW_CMD_NEW,
> +                                                      ufid_flags);
>                         BUG_ON(error < 0);
>                 }
>                 ovs_unlock();
> @@ -950,14 +1017,16 @@ static int ovs_flow_cmd_new(struct sk_buff *skb, struct genl_info *info)
>                         error = -EEXIST;
>                         goto err_unlock_ovs;
>                 }
> -               /* The unmasked key has to be the same for flow updates. */
> -               if (unlikely(!ovs_flow_cmp_unmasked_key(flow, &match))) {
> -                       /* Look for any overlapping flow. */
> +               /* The flow identifier has to be the same for flow updates. */
> +               if (sfid.ufid_len) {
> +                       if (unlikely(!ovs_flow_cmp_ufid(flow, &sfid)))
> +                               flow = NULL;
> +               } else if (unlikely(!ovs_flow_cmp_unmasked_key(flow, &match))) {
>                         flow = ovs_flow_tbl_lookup_exact(&dp->table, &match);
> -                       if (!flow) {
> -                               error = -ENOENT;
> -                               goto err_unlock_ovs;
> -                       }
> +               }
> +               if (unlikely(!flow)) {
> +                       error = -ENOENT;
> +                       goto err_unlock_ovs;
>                 }
>                 /* Update actions. */
>                 old_acts = ovsl_dereference(flow->sf_acts);
> @@ -968,7 +1037,8 @@ static int ovs_flow_cmd_new(struct sk_buff *skb, struct genl_info *info)
>                                                        ovs_header->dp_ifindex,
>                                                        reply, info->snd_portid,
>                                                        info->snd_seq, 0,
> -                                                      OVS_FLOW_CMD_NEW);
> +                                                      OVS_FLOW_CMD_NEW,
> +                                                      ufid_flags);
>                         BUG_ON(error < 0);
>                 }
>                 ovs_unlock();
> @@ -1018,30 +1088,36 @@ static int ovs_flow_cmd_set(struct sk_buff *skb, struct genl_info *info)
>         struct nlattr **a = info->attrs;
>         struct ovs_header *ovs_header = info->userhdr;
>         struct sw_flow_key key;
> -       struct sw_flow *flow;
> +       struct sw_flow *flow = NULL;
>         struct sw_flow_mask mask;
>         struct sk_buff *reply = NULL;
>         struct datapath *dp;
>         struct sw_flow_actions *old_acts = NULL, *acts = NULL;
>         struct sw_flow_match match;
> +       struct sw_flow_id ufid;
> +       u32 ufid_flags;
>         int error;
>         bool log = !a[OVS_FLOW_ATTR_PROBE];
>
> -       /* Extract key. */
> -       error = -EINVAL;
> -       if (!a[OVS_FLOW_ATTR_KEY]) {
> -               OVS_NLERR(log, "Flow key attribute not present in set flow.");
> +       /* Extract ufid/key. */
> +       error = ovs_nla_get_ufid(a[OVS_FLOW_ATTR_UFID], &ufid,
> +                                &ufid_flags);
> +       if (error)
>                 goto error;
> +       if (a[OVS_FLOW_ATTR_KEY]) {
> +               ovs_match_init(&match, &key, &mask);
> +               error = ovs_nla_get_match(&match, a[OVS_FLOW_ATTR_KEY],
> +                                         a[OVS_FLOW_ATTR_MASK], log);
> +       } else if (!ufid.ufid_len) {
> +               OVS_NLERR(log, "Flow key attribute not present in set flow.\n");
> +               error = -EINVAL;
>         }
> -
> -       ovs_match_init(&match, &key, &mask);
> -       error = ovs_nla_get_match(&match, a[OVS_FLOW_ATTR_KEY],
> -                                 a[OVS_FLOW_ATTR_MASK], log);
>         if (error)
>                 goto error;
>
>         /* Validate actions. */
> -       if (a[OVS_FLOW_ATTR_ACTIONS]) {
> +       if (a[OVS_FLOW_ATTR_ACTIONS] && a[OVS_FLOW_ATTR_KEY] &&
> +           a[OVS_FLOW_ATTR_MASK]) {
>                 acts = get_flow_actions(a[OVS_FLOW_ATTR_ACTIONS], &key, &mask,
>                                         log);
>                 if (IS_ERR(acts)) {
> @@ -1050,7 +1126,7 @@ static int ovs_flow_cmd_set(struct sk_buff *skb, struct genl_info *info)
>                 }
>
>                 /* Can allocate before locking if have acts. */
> -               reply = ovs_flow_cmd_alloc_info(acts, info, false);
> +               reply = ovs_flow_cmd_alloc_info(acts, &ufid, info, false);
>                 if (IS_ERR(reply)) {
>                         error = PTR_ERR(reply);
>                         goto err_kfree_acts;
> @@ -1064,7 +1140,10 @@ static int ovs_flow_cmd_set(struct sk_buff *skb, struct genl_info *info)
>                 goto err_unlock_ovs;
>         }
>         /* Check that the flow exists. */
> -       flow = ovs_flow_tbl_lookup_exact(&dp->table, &match);
> +       if (ufid.ufid_len)
> +               flow = ovs_flow_tbl_lookup_ufid(&dp->table, &ufid);
> +       else
> +               flow = ovs_flow_tbl_lookup_exact(&dp->table, &match);
>         if (unlikely(!flow)) {
>                 error = -ENOENT;
>                 goto err_unlock_ovs;
> @@ -1080,13 +1159,15 @@ static int ovs_flow_cmd_set(struct sk_buff *skb, struct genl_info *info)
>                                                        ovs_header->dp_ifindex,
>                                                        reply, info->snd_portid,
>                                                        info->snd_seq, 0,
> -                                                      OVS_FLOW_CMD_NEW);
> +                                                      OVS_FLOW_CMD_NEW,
> +                                                      ufid_flags);
>                         BUG_ON(error < 0);
>                 }
>         } else {
>                 /* Could not alloc without acts before locking. */
>                 reply = ovs_flow_cmd_build_info(flow, ovs_header->dp_ifindex,
> -                                               info, OVS_FLOW_CMD_NEW, false);
> +                                               info, OVS_FLOW_CMD_NEW, false,
> +                                               ufid_flags);
>                 if (unlikely(IS_ERR(reply))) {
>                         error = PTR_ERR(reply);
>                         goto err_unlock_ovs;
> @@ -1123,17 +1204,22 @@ static int ovs_flow_cmd_get(struct sk_buff *skb, struct genl_info *info)
>         struct sw_flow *flow;
>         struct datapath *dp;
>         struct sw_flow_match match;
> +       struct sw_flow_id ufid;
> +       u32 ufid_flags;
>         int err;
>         bool log = !a[OVS_FLOW_ATTR_PROBE];
>
> -       if (!a[OVS_FLOW_ATTR_KEY]) {
> +       err = ovs_nla_get_ufid(a[OVS_FLOW_ATTR_UFID], &ufid, &ufid_flags);
> +       if (err)
> +               return err;
> +       if (a[OVS_FLOW_ATTR_KEY]) {
> +               ovs_match_init(&match, &key, NULL);
> +               err = ovs_nla_get_match(&match, a[OVS_FLOW_ATTR_KEY], NULL, log);
> +       } else if (!ufid.ufid_len) {
>                 OVS_NLERR(log,
> -                         "Flow get message rejected, Key attribute missing.");
> -               return -EINVAL;
> +                         "Flow get message rejected, Key attribute missing.\n");
> +               err = -EINVAL;
>         }
> -
> -       ovs_match_init(&match, &key, NULL);
> -       err = ovs_nla_get_match(&match, a[OVS_FLOW_ATTR_KEY], NULL, log);
>         if (err)
>                 return err;
>
> @@ -1144,14 +1230,17 @@ static int ovs_flow_cmd_get(struct sk_buff *skb, struct genl_info *info)
>                 goto unlock;
>         }
>
> -       flow = ovs_flow_tbl_lookup_exact(&dp->table, &match);
> +       if (ufid.ufid_len)
> +               flow = ovs_flow_tbl_lookup_ufid(&dp->table, &ufid);
> +       else
> +               flow = ovs_flow_tbl_lookup_exact(&dp->table, &match);
>         if (!flow) {
>                 err = -ENOENT;
>                 goto unlock;
>         }
>
>         reply = ovs_flow_cmd_build_info(flow, ovs_header->dp_ifindex, info,
> -                                       OVS_FLOW_CMD_NEW, true);
> +                                       OVS_FLOW_CMD_NEW, true, ufid_flags);
>         if (IS_ERR(reply)) {
>                 err = PTR_ERR(reply);
>                 goto unlock;
> @@ -1170,13 +1259,18 @@ static int ovs_flow_cmd_del(struct sk_buff *skb, struct genl_info *info)
>         struct ovs_header *ovs_header = info->userhdr;
>         struct sw_flow_key key;
>         struct sk_buff *reply;
> -       struct sw_flow *flow;
> +       struct sw_flow *flow = NULL;
>         struct datapath *dp;
>         struct sw_flow_match match;
> +       struct sw_flow_id ufid;
> +       u32 ufid_flags;
>         int err;
>         bool log = !a[OVS_FLOW_ATTR_PROBE];
>
> -       if (likely(a[OVS_FLOW_ATTR_KEY])) {
> +       err = ovs_nla_get_ufid(a[OVS_FLOW_ATTR_UFID], &ufid, &ufid_flags);
> +       if (err)
> +               return err;
> +       if (a[OVS_FLOW_ATTR_KEY]) {
>                 ovs_match_init(&match, &key, NULL);
>                 err = ovs_nla_get_match(&match, a[OVS_FLOW_ATTR_KEY], NULL,
>                                         log);
> @@ -1191,12 +1285,15 @@ static int ovs_flow_cmd_del(struct sk_buff *skb, struct genl_info *info)
>                 goto unlock;
>         }
>
> -       if (unlikely(!a[OVS_FLOW_ATTR_KEY])) {
> +       if (unlikely(!a[OVS_FLOW_ATTR_KEY] && !ufid.ufid_len)) {
>                 err = ovs_flow_tbl_flush(&dp->table);
>                 goto unlock;
>         }
>
> -       flow = ovs_flow_tbl_lookup_exact(&dp->table, &match);
> +       if (ufid.ufid_len)
> +               flow = ovs_flow_tbl_lookup_ufid(&dp->table, &ufid);
> +       else
> +               flow = ovs_flow_tbl_lookup_exact(&dp->table, &match);
>         if (unlikely(!flow)) {
>                 err = -ENOENT;
>                 goto unlock;
> @@ -1206,7 +1303,7 @@ static int ovs_flow_cmd_del(struct sk_buff *skb, struct genl_info *info)
>         ovs_unlock();
>
>         reply = ovs_flow_cmd_alloc_info(rcu_dereference_raw(flow->sf_acts),
> -                                       info, false);
> +                                       flow_get_ufid(flow), info, false);
>
>         if (likely(reply)) {
>                 if (likely(!IS_ERR(reply))) {
> @@ -1214,7 +1311,8 @@ static int ovs_flow_cmd_del(struct sk_buff *skb, struct genl_info *info)
>                         err = ovs_flow_cmd_fill_info(flow, ovs_header->dp_ifindex,
>                                                      reply, info->snd_portid,
>                                                      info->snd_seq, 0,
> -                                                    OVS_FLOW_CMD_DEL);
> +                                                    OVS_FLOW_CMD_DEL,
> +                                                    ufid_flags);
>                         rcu_read_unlock();
>                         BUG_ON(err < 0);
>                         ovs_notify(&dp_flow_genl_family, &ovs_dp_flow_multicast_group, reply, info);
> @@ -1235,8 +1333,15 @@ unlock:
>  static int ovs_flow_cmd_dump(struct sk_buff *skb, struct netlink_callback *cb)
>  {
>         struct ovs_header *ovs_header = genlmsg_data(nlmsg_data(cb->nlh));
> +       struct nlattr *nla, *ufid;
>         struct table_instance *ti;
>         struct datapath *dp;
> +       u32 ufid_flags = 0;
> +
> +       nla = nlmsg_attrdata(cb->nlh, sizeof(*ovs_header));
> +       ufid = nla_find_nested(nla, OVS_FLOW_ATTR_UFID);
> +       if (ufid && ovs_nla_get_ufid(ufid, NULL, &ufid_flags))
> +               OVS_NLERR(true, "Error occurred parsing UFID flags on dump");
>
>         rcu_read_lock();
>         dp = get_dp_rcu(sock_net(skb->sk), ovs_header->dp_ifindex);
> @@ -1259,7 +1364,7 @@ static int ovs_flow_cmd_dump(struct sk_buff *skb, struct netlink_callback *cb)
>                 if (ovs_flow_cmd_fill_info(flow, ovs_header->dp_ifindex, skb,
>                                            NETLINK_CB(cb->skb).portid,
>                                            cb->nlh->nlmsg_seq, NLM_F_MULTI,
> -                                          OVS_FLOW_CMD_NEW) < 0)
> +                                          OVS_FLOW_CMD_NEW, ufid_flags) < 0)
>                         break;
>
>                 cb->args[0] = bucket;
> @@ -1275,6 +1380,7 @@ static const struct nla_policy flow_policy[OVS_FLOW_ATTR_MAX + 1] = {
>         [OVS_FLOW_ATTR_ACTIONS] = { .type = NLA_NESTED },
>         [OVS_FLOW_ATTR_CLEAR] = { .type = NLA_FLAG },
>         [OVS_FLOW_ATTR_PROBE] = { .type = NLA_FLAG },
> +       [OVS_FLOW_ATTR_UFID] = { .type = NLA_NESTED },
>  };
>
>  static struct genl_ops dp_flow_genl_ops[] = {
> diff --git a/datapath/flow.h b/datapath/flow.h
> index 2bbf789..736e0eb 100644
> --- a/datapath/flow.h
> +++ b/datapath/flow.h
> @@ -196,6 +196,13 @@ struct sw_flow_match {
>         struct sw_flow_mask *mask;
>  };
>
> +struct sw_flow_id {
> +       struct hlist_node node[2];
> +       u32 hash;
> +       u8 *ufid;
> +       u8 ufid_len;
> +};
> +
Lets make ufid array of size 256, we can reject any key greater than
this. current patch does not support key greater than 256 anyways.

>  struct sw_flow_actions {
>         struct rcu_head rcu;
>         u32 actions_len;
> @@ -212,13 +219,20 @@ struct flow_stats {
>
>  struct sw_flow {
>         struct rcu_head rcu;
> -       struct hlist_node hash_node[2];
> -       u32 hash;
> +       struct {
> +               struct hlist_node node[2];
> +               u32 hash;
> +       } flow_hash;
This change does not look related to this work.

>         int stats_last_writer;          /* NUMA-node id of the last writer on
>                                          * 'stats[0]'.
>                                          */
>         struct sw_flow_key key;
> -       struct sw_flow_key unmasked_key;
> +       bool index_by_ufid;             /* Which of the below that userspace
> +                                          uses to index this flow. */
> +       union {
> +               struct sw_flow_key unmasked_key;
> +               struct sw_flow_id ufid;
> +       } index;
Rather than storing ufid or unmasked key inside struct flow we can
keep pointer to these objects, that will save some memory.

>         struct sw_flow_mask *mask;
>         struct sw_flow_actions __rcu *sf_acts;
>         struct flow_stats __rcu *stats[]; /* One for each NUMA node.  First one
> diff --git a/datapath/flow_netlink.c b/datapath/flow_netlink.c
> index c1c29f5..7927462 100644
> --- a/datapath/flow_netlink.c
> +++ b/datapath/flow_netlink.c
> @@ -1094,6 +1094,41 @@ free_newmask:
>         return err;
>  }
>
> +int ovs_nla_get_ufid(const struct nlattr *attr, struct sw_flow_id *sfid,
> +                    u32 *flags)
> +{
> +       static const struct nla_policy ovs_ufid_policy[OVS_UFID_ATTR_MAX + 1] = {
> +               [OVS_UFID_ATTR_FLAGS] = { .type = NLA_U32 },
> +               [OVS_UFID_ATTR_ID] = { .len = sizeof(u32) },
> +       };
> +       const struct nlattr *a[OVS_UFID_ATTR_MAX + 1];
> +       int err;
> +
> +       if (sfid) {
> +               sfid->ufid = NULL;
> +               sfid->ufid_len = 0;
> +       }
> +       if (flags)
> +               *flags = 0;
> +       if (!attr)
> +               return 0;
> +
> +       err = nla_parse_nested((struct nlattr **)a, OVS_UFID_ATTR_MAX, attr,
> +                              ovs_ufid_policy);
> +       if (err)
> +               return err;
> +
> +       if (sfid && a[OVS_UFID_ATTR_ID]) {
> +               sfid->ufid = nla_data(a[OVS_UFID_ATTR_ID]);
> +               sfid->ufid_len = nla_len(a[OVS_UFID_ATTR_ID]);
> +       }
> +
> +       if (flags && a[OVS_UFID_ATTR_FLAGS])
> +               *flags = nla_get_u32(a[OVS_UFID_ATTR_FLAGS]);
> +
> +       return 0;
> +}
> +
>  /**
>   * ovs_nla_get_flow_metadata - parses Netlink attributes into a flow key.
>   * @key: Receives extracted in_port, priority, tun_key and skb_mark.
> diff --git a/datapath/flow_netlink.h b/datapath/flow_netlink.h
> index fde7616..9a14ad9 100644
> --- a/datapath/flow_netlink.h
> +++ b/datapath/flow_netlink.h
> @@ -52,6 +52,7 @@ int ovs_nla_get_match(struct sw_flow_match *, const struct nlattr *key,
>                       const struct nlattr *mask, bool log);
>  int ovs_nla_put_egress_tunnel_key(struct sk_buff *,
>                                   const struct ovs_tunnel_info *);
> +int ovs_nla_get_ufid(const struct nlattr *, struct sw_flow_id *, u32 *flags);
>
>  int ovs_nla_copy_actions(const struct nlattr *attr,
>                          const struct sw_flow_key *key,
> diff --git a/datapath/flow_table.c b/datapath/flow_table.c
> index ad410fd..03e7040 100644
> --- a/datapath/flow_table.c
> +++ b/datapath/flow_table.c
> @@ -92,6 +92,7 @@ struct sw_flow *ovs_flow_alloc(void)
>
>         flow->sf_acts = NULL;
>         flow->mask = NULL;
> +       flow->index_by_ufid = false;
>         flow->stats_last_writer = NUMA_NO_NODE;
>
>         /* Initialize the default stat node. */
> @@ -146,6 +147,8 @@ static void flow_free(struct sw_flow *flow)
>  {
>         int node;
>
> +       if (flow->index_by_ufid)
> +               kfree(flow->index.ufid.ufid);
>         kfree(rcu_dereference_raw(flow->sf_acts));
>         for_each_node(node)
>                 if (flow->stats[node])
> @@ -265,7 +268,7 @@ static int tbl_mask_array_realloc(struct flow_table *tbl, int size)
>
>  int ovs_flow_tbl_init(struct flow_table *table)
>  {
> -       struct table_instance *ti;
> +       struct table_instance *ti, *ufid_ti;
>         struct mask_array *ma;
>
>         table->mask_cache = __alloc_percpu(sizeof(struct mask_cache_entry) *
> @@ -277,16 +280,24 @@ int ovs_flow_tbl_init(struct flow_table *table)
>         if (!ma)
>                 goto free_mask_cache;
>
> +       ufid_ti = table_instance_alloc(TBL_MIN_BUCKETS);
> +       if (!ufid_ti)
> +               goto free_mask_array;
> +
>         ti = table_instance_alloc(TBL_MIN_BUCKETS);
>         if (!ti)
> -               goto free_mask_array;
> +               goto free_ti;
>
>         rcu_assign_pointer(table->ti, ti);
> +       rcu_assign_pointer(table->ufid_ti, ufid_ti);
>         rcu_assign_pointer(table->mask_array, ma);
> -       table->last_rehash = jiffies;
>         table->count = 0;
> +       table->ufid_count = 0;
> +       table->last_rehash = jiffies;
>         return 0;
>
> +free_ti:
> +       __table_instance_destroy(ufid_ti);
>  free_mask_array:
>         kfree(ma);
>  free_mask_cache:
> @@ -301,13 +312,16 @@ static void flow_tbl_destroy_rcu_cb(struct rcu_head *rcu)
>         __table_instance_destroy(ti);
>  }
>
> -static void table_instance_destroy(struct table_instance *ti, bool deferred)
> +static void table_instance_destroy(struct table_instance *ti,
> +                                  struct table_instance *ufid_ti,
> +                                  bool deferred)
>  {
>         int i;
>
>         if (!ti)
>                 return;
>
> +       BUG_ON(!ufid_ti);
>         if (ti->keep_flows)
>                 goto skip_flows;
>
> @@ -316,18 +330,24 @@ static void table_instance_destroy(struct table_instance *ti, bool deferred)
>                 struct hlist_head *head = flex_array_get(ti->buckets, i);
>                 struct hlist_node *n;
>                 int ver = ti->node_ver;
> +               int ufid_ver = ufid_ti->node_ver;
>
> -               hlist_for_each_entry_safe(flow, n, head, hash_node[ver]) {
> -                       hlist_del_rcu(&flow->hash_node[ver]);
> +               hlist_for_each_entry_safe(flow, n, head, flow_hash.node[ver]) {
> +                       hlist_del_rcu(&flow->flow_hash.node[ver]);
> +                       if (flow->index_by_ufid)
> +                               hlist_del_rcu(&flow->index.ufid.node[ufid_ver]);
>                         ovs_flow_free(flow, deferred);
>                 }
>         }
>
>  skip_flows:
> -       if (deferred)
> +       if (deferred) {
>                 call_rcu(&ti->rcu, flow_tbl_destroy_rcu_cb);
> -       else
> +               call_rcu(&ufid_ti->rcu, flow_tbl_destroy_rcu_cb);
> +       } else {
>                 __table_instance_destroy(ti);
> +               __table_instance_destroy(ufid_ti);
> +       }
>  }
>
>  /* No need for locking this function is called from RCU callback or
> @@ -336,10 +356,11 @@ skip_flows:
>  void ovs_flow_tbl_destroy(struct flow_table *table)
>  {
>         struct table_instance *ti = rcu_dereference_raw(table->ti);
> +       struct table_instance *ufid_ti = rcu_dereference_raw(table->ufid_ti);
>
>         free_percpu(table->mask_cache);
> -       kfree(rcu_dereference_raw(table->mask_array));
> -       table_instance_destroy(ti, false);
> +       kfree((struct mask_array __force *)table->mask_array);
> +       table_instance_destroy(ti, ufid_ti, false);
>  }
>
>  struct sw_flow *ovs_flow_tbl_dump_next(struct table_instance *ti,
> @@ -354,7 +375,7 @@ struct sw_flow *ovs_flow_tbl_dump_next(struct table_instance *ti,
>         while (*bucket < ti->n_buckets) {
>                 i = 0;
>                 head = flex_array_get(ti->buckets, *bucket);
> -               hlist_for_each_entry_rcu(flow, head, hash_node[ver]) {
> +               hlist_for_each_entry_rcu(flow, head, flow_hash.node[ver]) {
>                         if (i < *last) {
>                                 i++;
>                                 continue;
> @@ -380,12 +401,21 @@ static void table_instance_insert(struct table_instance *ti, struct sw_flow *flo
>  {
>         struct hlist_head *head;
>
> -       head = find_bucket(ti, flow->hash);
> -       hlist_add_head_rcu(&flow->hash_node[ti->node_ver], head);
> +       head = find_bucket(ti, flow->flow_hash.hash);
> +       hlist_add_head_rcu(&flow->flow_hash.node[ti->node_ver], head);
> +}
> +
> +static void ufid_table_instance_insert(struct table_instance *ti,
> +                                      struct sw_flow *flow)
> +{
> +       struct hlist_head *head;
> +
> +       head = find_bucket(ti, flow->index.ufid.hash);
> +       hlist_add_head_rcu(&flow->index.ufid.node[ti->node_ver], head);
>  }
>
>  static void flow_table_copy_flows(struct table_instance *old,
> -                                 struct table_instance *new)
> +                                 struct table_instance *new, bool ufid)
>  {
>         int old_ver;
>         int i;
> @@ -400,42 +430,69 @@ static void flow_table_copy_flows(struct table_instance *old,
>
>                 head = flex_array_get(old->buckets, i);
>
> -               hlist_for_each_entry(flow, head, hash_node[old_ver])
> -                       table_instance_insert(new, flow);
> +               if (ufid)
> +                       hlist_for_each_entry(flow, head,
> +                                            index.ufid.node[old_ver])
> +                               ufid_table_instance_insert(new, flow);
> +               else
> +                       hlist_for_each_entry(flow, head, flow_hash.node[old_ver])
> +                               table_instance_insert(new, flow);
>         }
>
>         old->keep_flows = true;
>  }
>
> -static struct table_instance *table_instance_rehash(struct table_instance *ti,
> -                                           int n_buckets)
> +static int flow_table_instance_alloc(struct table_instance **ti,
> +                                    int n_buckets)
>  {
>         struct table_instance *new_ti;
>
>         new_ti = table_instance_alloc(n_buckets);
>         if (!new_ti)
> -               return NULL;
> +               return -ENOMEM;
>
> -       flow_table_copy_flows(ti, new_ti);
> +       *ti = new_ti;
> +       return 0;
> +}
> +
> +static struct table_instance *flow_table_rehash(struct table_instance *old_ti,
> +                                               int n_buckets, bool ufid)
> +{
> +       struct table_instance *new_ti;
> +       int err;
> +
> +       err = flow_table_instance_alloc(&new_ti, n_buckets);
> +       if (err)
> +               return NULL;
> +       flow_table_copy_flows(old_ti, new_ti, ufid);
>
>         return new_ti;
>  }
>
>  int ovs_flow_tbl_flush(struct flow_table *flow_table)
>  {
> -       struct table_instance *old_ti;
> -       struct table_instance *new_ti;
> +       struct table_instance *old_ti, *new_ti, *old_ufid_ti;
> +       struct table_instance *new_ufid_ti = NULL;
> +       int err;
>
>         old_ti = ovsl_dereference(flow_table->ti);
> -       new_ti = table_instance_alloc(TBL_MIN_BUCKETS);
> -       if (!new_ti)
> -               return -ENOMEM;
> +       old_ufid_ti = ovsl_dereference(flow_table->ufid_ti);
> +       err = flow_table_instance_alloc(&new_ti, TBL_MIN_BUCKETS);
> +       if (err)
> +               return err;
> +       err = flow_table_instance_alloc(&new_ufid_ti, TBL_MIN_BUCKETS);
> +       if (err) {
> +               __table_instance_destroy(new_ti);
> +               return err;
> +       }
>
>         rcu_assign_pointer(flow_table->ti, new_ti);
> +       rcu_assign_pointer(flow_table->ufid_ti, new_ufid_ti);
>         flow_table->last_rehash = jiffies;
>         flow_table->count = 0;
> +       flow_table->ufid_count = 0;
>
> -       table_instance_destroy(old_ti, true);
> +       table_instance_destroy(old_ti, old_ufid_ti, true);
>         return 0;
>  }
>
> @@ -489,7 +546,8 @@ bool ovs_flow_cmp_unmasked_key(const struct sw_flow *flow,
>         int key_start = flow_key_start(key);
>         int key_end = match->range.end;
>
> -       return cmp_key(&flow->unmasked_key, key, key_start, key_end);
> +       BUG_ON(flow->index_by_ufid);
> +       return cmp_key(&flow->index.unmasked_key, key, key_start, key_end);
>  }
>
>  static struct sw_flow *masked_flow_lookup(struct table_instance *ti,
> @@ -508,10 +566,9 @@ static struct sw_flow *masked_flow_lookup(struct table_instance *ti,
>         hash = flow_hash(&masked_key, key_start, key_end);
>         head = find_bucket(ti, hash);
>         (*n_mask_hit)++;
> -       hlist_for_each_entry_rcu(flow, head, hash_node[ti->node_ver]) {
> -               if (flow->mask == mask && flow->hash == hash &&
> -                   flow_cmp_masked_key(flow, &masked_key,
> -                                         key_start, key_end))
> +       hlist_for_each_entry_rcu(flow, head, flow_hash.node[ti->node_ver]) {
> +               if (flow->mask == mask && flow->flow_hash.hash == hash &&
> +                   flow_cmp_masked_key(flow, &masked_key, key_start, key_end))
>                         return flow;
>         }
>         return NULL;
> @@ -644,7 +701,40 @@ struct sw_flow *ovs_flow_tbl_lookup_exact(struct flow_table *tbl,
>                 if (!mask)
>                         continue;
>                 flow = masked_flow_lookup(ti, match->key, mask, &n_mask_hit);
> -               if (flow && ovs_flow_cmp_unmasked_key(flow, match))
> +               if (flow && !flow->index_by_ufid &&
> +                   ovs_flow_cmp_unmasked_key(flow, match))
> +                       return flow;
> +       }
> +       return NULL;
> +}
> +
> +static u32 ufid_hash(const struct sw_flow_id *sfid)
> +{
> +       return arch_fast_hash(sfid->ufid, sfid->ufid_len, 0);
> +}
> +
> +bool ovs_flow_cmp_ufid(const struct sw_flow *flow,
> +                      const struct sw_flow_id *sfid)
> +{
> +       if (flow->index.ufid.ufid_len != sfid->ufid_len)
> +               return false;
> +
> +       return !memcmp(flow->index.ufid.ufid, sfid->ufid, sfid->ufid_len);
> +}
> +
> +struct sw_flow *ovs_flow_tbl_lookup_ufid(struct flow_table *tbl,
> +                                        const struct sw_flow_id *ufid)
> +{
> +       struct table_instance *ti = rcu_dereference_ovsl(tbl->ufid_ti);
> +       struct sw_flow *flow;
> +       struct hlist_head *head;
> +       u32 hash;
> +
> +       hash = ufid_hash(ufid);
> +       head = find_bucket(ti, hash);
> +       hlist_for_each_entry_rcu(flow, head, index.ufid.node[ti->node_ver]) {
> +               if (flow->index.ufid.hash == hash &&
> +                   ovs_flow_cmp_ufid(flow, ufid))
>                         return flow;
>         }
>         return NULL;
> @@ -658,9 +748,10 @@ int ovs_flow_tbl_num_masks(const struct flow_table *table)
>         return ma->count;
>  }
>
> -static struct table_instance *table_instance_expand(struct table_instance *ti)
> +static struct table_instance *flow_table_expand(struct table_instance *old_ti,
> +                                               bool ufid)
>  {
> -       return table_instance_rehash(ti, ti->n_buckets * 2);
> +       return flow_table_rehash(old_ti, old_ti->n_buckets * 2, ufid);
>  }
>
>  static void tbl_mask_array_delete_mask(struct mask_array *ma,
> @@ -710,10 +801,15 @@ static void flow_mask_remove(struct flow_table *tbl, struct sw_flow_mask *mask)
>  void ovs_flow_tbl_remove(struct flow_table *table, struct sw_flow *flow)
>  {
>         struct table_instance *ti = ovsl_dereference(table->ti);
> +       struct table_instance *ufid_ti = ovsl_dereference(table->ufid_ti);
>
>         BUG_ON(table->count == 0);
> -       hlist_del_rcu(&flow->hash_node[ti->node_ver]);
> +       hlist_del_rcu(&flow->flow_hash.node[ti->node_ver]);
>         table->count--;
> +       if (flow->index_by_ufid) {
> +               hlist_del_rcu(&flow->index.ufid.node[ufid_ti->node_ver]);
> +               table->ufid_count--;
> +       }
>
>         /* RCU delete the mask. 'flow->mask' is not NULLed, as it should be
>          * accessible as long as the RCU read lock is held.
> @@ -818,31 +914,65 @@ static int flow_mask_insert(struct flow_table *tbl, struct sw_flow *flow,
>  int ovs_flow_tbl_insert(struct flow_table *table, struct sw_flow *flow,
>                         const struct sw_flow_mask *mask)
>  {
> -       struct table_instance *new_ti = NULL;
> -       struct table_instance *ti;
> +       struct table_instance *new_ti = NULL, *new_ufid_ti = NULL;
> +       struct table_instance *ti, *ufid_ti = NULL;
>         int err;
>
>         err = flow_mask_insert(table, flow, mask);
>         if (err)
>                 return err;
>
> -       flow->hash = flow_hash(&flow->key, flow->mask->range.start,
> -                       flow->mask->range.end);
> +       flow->flow_hash.hash = flow_hash(&flow->key, flow->mask->range.start,
> +                                        flow->mask->range.end);
>         ti = ovsl_dereference(table->ti);
>         table_instance_insert(ti, flow);
>         table->count++;
> +       if (flow->index_by_ufid) {
> +               flow->index.ufid.hash = ufid_hash(&flow->index.ufid);
> +               ufid_ti = ovsl_dereference(table->ufid_ti);
> +               ufid_table_instance_insert(ufid_ti, flow);
> +               table->ufid_count++;
> +       }
>
>         /* Expand table, if necessary, to make room. */
>         if (table->count > ti->n_buckets)
> -               new_ti = table_instance_expand(ti);
> +               new_ti = flow_table_expand(ti, false);
>         else if (time_after(jiffies, table->last_rehash + REHASH_INTERVAL))
> -               new_ti = table_instance_rehash(ti, ti->n_buckets);
> +               new_ti = flow_table_rehash(ti, ti->n_buckets, false);
> +       if (ufid_ti && table->ufid_count > ufid_ti->n_buckets)
> +               new_ufid_ti = flow_table_expand(ufid_ti, true);
>
>         if (new_ti) {
>                 rcu_assign_pointer(table->ti, new_ti);
> -               table_instance_destroy(ti, true);
> +               call_rcu(&ti->rcu, flow_tbl_destroy_rcu_cb);
>                 table->last_rehash = jiffies;
>         }
> +       if (new_ufid_ti) {
> +               rcu_assign_pointer(table->ufid_ti, new_ufid_ti);
> +               call_rcu(&ufid_ti->rcu, flow_tbl_destroy_rcu_cb);
> +       }
> +       return 0;
> +}
Insert function can be simplified by first updating flow-table and
then updating ufid table.

> +
> +/* Initializes 'flow->ufid'. */
> +int ovs_flow_ufid(struct sw_flow *flow, const struct sw_flow_id *src)
> +{
> +       if (src->ufid_len) {
> +               struct sw_flow_id *dst = &flow->index.ufid;
> +
> +               /* Use userspace-specified flow-id. */
> +               dst->ufid = kmalloc(src->ufid_len, GFP_KERNEL);
> +               if (!dst->ufid)
> +                       return -ENOMEM;
> +
> +               memcpy(dst->ufid, src->ufid, src->ufid_len);
> +               dst->ufid_len = src->ufid_len;
> +               flow->index_by_ufid = true;
> +       } else {
> +               /* Don't index by UFID. */
> +               flow->index_by_ufid = false;
> +       }
> +
>         return 0;
>  }
>
> diff --git a/datapath/flow_table.h b/datapath/flow_table.h
> index 80c01a3..e05b59c 100644
> --- a/datapath/flow_table.h
> +++ b/datapath/flow_table.h
> @@ -60,8 +60,10 @@ struct flow_table {
>         struct table_instance __rcu *ti;
>         struct mask_cache_entry __percpu *mask_cache;
>         struct mask_array __rcu *mask_array;
> +       struct table_instance __rcu *ufid_ti;
>         unsigned long last_rehash;
>         unsigned int count;
> +       unsigned int ufid_count;
>  };
>
>  extern struct kmem_cache *flow_stats_cache;
> @@ -91,9 +93,15 @@ struct sw_flow *ovs_flow_tbl_lookup(struct flow_table *,
>                                     const struct sw_flow_key *);
>  struct sw_flow *ovs_flow_tbl_lookup_exact(struct flow_table *tbl,
>                                           const struct sw_flow_match *match);
> +struct sw_flow *ovs_flow_tbl_lookup_ufid(struct flow_table *,
> +                                        const struct sw_flow_id *);
> +
>  bool ovs_flow_cmp_unmasked_key(const struct sw_flow *flow,
>                                const struct sw_flow_match *match);
> +bool ovs_flow_cmp_ufid(const struct sw_flow *flow,
> +                      const struct sw_flow_id *sfid);
>
>  void ovs_flow_mask_key(struct sw_flow_key *dst, const struct sw_flow_key *src,
>                        const struct sw_flow_mask *mask);
> +int ovs_flow_ufid(struct sw_flow *flow, const struct sw_flow_id *src);
>  #endif /* flow_table.h */
> diff --git a/datapath/linux/compat/include/linux/openvswitch.h b/datapath/linux/compat/include/linux/openvswitch.h
> index c8fa66e..7d759a4 100644
> --- a/datapath/linux/compat/include/linux/openvswitch.h
> +++ b/datapath/linux/compat/include/linux/openvswitch.h
> @@ -471,6 +471,9 @@ struct ovs_key_nd {
>   * a wildcarded match. Omitting attribute is treated as wildcarding all
>   * corresponding fields. Optional for all requests. If not present,
>   * all flow key bits are exact match bits.
> + * @OVS_FLOW_ATTR_UFID: Nested %OVS_UFID_ATTR_* attributes specifying unique
> + * identifiers for flows and providing alternative semantics for flow
> + * installation and retrieval.
>   *
>   * These attributes follow the &struct ovs_header within the Generic Netlink
>   * payload for %OVS_FLOW_* commands.
> @@ -486,12 +489,39 @@ enum ovs_flow_attr {
>         OVS_FLOW_ATTR_MASK,      /* Sequence of OVS_KEY_ATTR_* attributes. */
>         OVS_FLOW_ATTR_PROBE,     /* Flow operation is a feature probe, error
>                                   * logging should be suppressed. */
> +       OVS_FLOW_ATTR_UFID,      /* Unique flow identifier. */
>         __OVS_FLOW_ATTR_MAX
>  };
>
>  #define OVS_FLOW_ATTR_MAX (__OVS_FLOW_ATTR_MAX - 1)
>
>  /**
> + * enum ovs_ufid_attr - Unique identifier types.
> + *
> + * @OVS_UFID_ATTR_FLAGS: A 32-bit value specifying changes to the behaviour of
> + * the current %OVS_FLOW_CMD_* request. Optional for all requests.
> + * @OVS_UFID_ATTR_ID: A unique identifier for a flow.
> + */
> +enum ovs_ufid_attr {
> +       OVS_UFID_ATTR_UNSPEC,
> +       OVS_UFID_ATTR_FLAGS,     /* u32 of OVS_UFID_F_* */
> +       OVS_UFID_ATTR_ID,        /* variable length identifier. */
> +       __OVS_UFID_ATTR_MAX
> +};
> +
> +#define OVS_UFID_ATTR_MAX (__OVS_UFID_ATTR_MAX - 1)
> +
> +/**
> + * Omit attributes for notifications.
> + *
> + * If a datapath request contains an OVS_UFID_F_OMIT_* flag, then the datapath
> + * may omit the corresponding 'ovs_flow_attr' from the response.
> + */
> +#define OVS_UFID_F_OMIT_KEY      (1 << 0)
> +#define OVS_UFID_F_OMIT_MASK     (1 << 1)
> +#define OVS_UFID_F_OMIT_ACTIONS  (1 << 2)
> +

These flags are related to flow operations. So OVS_UFID_ATTR_FLAGS
should be part of enum ovs_flow_attr.
This way we do not need to make UFID nested attr.

> +/**
>   * enum ovs_sample_attr - Attributes for %OVS_ACTION_ATTR_SAMPLE action.
>   * @OVS_SAMPLE_ATTR_PROBABILITY: 32-bit fraction of packets to sample with
>   * @OVS_ACTION_ATTR_SAMPLE.  A value of 0 samples no packets, a value of
> --
> 1.7.10.4
>
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On Wednesday, November 19, 2014 15:34:24 Pravin Shelar wrote:
> On Thu, Nov 13, 2014 at 11:17 AM, Joe Stringer <joestringer@nicira.com> 
wrote:
> > @@ -684,33 +691,43 @@ static size_t ovs_flow_cmd_msg_size(const struct
> > sw_flow_actions *acts)
> > 
> >  /* Called with ovs_mutex or RCU read lock. */
> >  static int ovs_flow_cmd_fill_match(const struct sw_flow *flow,
> > 
> > -                                  struct sk_buff *skb)
> > +                                  struct sk_buff *skb, u32 ufid_flags)
> > 
> >  {
> >  
> >         struct nlattr *nla;
> >         int err;
> > 
> > -       /* Fill flow key. */
> > -       nla = nla_nest_start(skb, OVS_FLOW_ATTR_KEY);
> > -       if (!nla)
> > -               return -EMSGSIZE;
> > -
> > -       err = ovs_nla_put_flow(&flow->unmasked_key, &flow->unmasked_key,
> > skb, -                              false);
> > -       if (err)
> > -               return err;
> > -
> > -       nla_nest_end(skb, nla);
> > +       /* Fill flow key. If userspace didn't specify a UFID, then ignore
> > the +        * OMIT_KEY flag. */
> > +       if (!(ufid_flags & OVS_UFID_F_OMIT_KEY) ||
> > +           !flow->index_by_ufid) {
> 
> I am not sure about this check, userspace needs to send atleast ufid
> or the unmasked key as id for flow. otherwise we shld flag error. Here
> we can serialize flow->key.
> There could be another function which takes care of flow-id
> serialization where we serialize use ufid or unmasked key as flow id.
> Lets group ufid and unmasked key together rather than masked key and
> unmasked key which are not related.

Right, at flow setup time the flow key is always required, but the UFID is 
optional. For most other cases, one of the two most be specified. For flow dump, 
neither is required from userspace, but OMIT_KEY flag may be raised. That's the 
particular case that this logic is trying to catch (dump all flows, including 
those that were set up without UFID - in which case the OMIT_KEY flag doesn't 
make sense, so treat the flag like a request rather than a command).

Happy to split the key/identifier out from the mask.
 
> > @@ -740,6 +757,32 @@ static int ovs_flow_cmd_fill_stats(const struct
> > sw_flow *flow,
> > 
> >  }
> >  
> >  /* Called with ovs_mutex or RCU read lock. */
> > 
> > +static int ovs_flow_cmd_fill_ufid(const struct sw_flow *flow,
> > +                                 struct sk_buff *skb)
> > +{
> > +       struct nlattr *start;
> > +       const struct sw_flow_id *sfid;
> > +
> > +       if (!flow->index_by_ufid)
> > +               return 0;
> > +
> > +       sfid = &flow->index.ufid;
> > +       start = nla_nest_start(skb, OVS_FLOW_ATTR_UFID);
> > +       if (start) {
> > +               int err;
> > +
> > +               err = nla_put(skb, OVS_UFID_ATTR_ID, sfid->ufid_len,
> > +                             sfid->ufid);
> > +               if (err)
> > +                       return err;
> > +               nla_nest_end(skb, start);
> > +       } else
> > +               return -EMSGSIZE;
> > +
> > +       return 0;
> > +}
> > +
> 
> Can you change this function according to comments above?

OK.

> > @@ -795,18 +838,24 @@ static int ovs_flow_cmd_fill_info(const struct
> > sw_flow *flow, int dp_ifindex,
> > 
> >         ovs_header->dp_ifindex = dp_ifindex;
> > 
> > -       err = ovs_flow_cmd_fill_match(flow, skb);
> > +       err = ovs_flow_cmd_fill_match(flow, skb, ufid_flags);
> > 
> >         if (err)
> >         
> >                 goto error;
> > 
> > -       err = ovs_flow_cmd_fill_stats(flow, skb);
> > +       err = ovs_flow_cmd_fill_ufid(flow, skb);
> > 
> >         if (err)
> >         
> >                 goto error;
> 
> Flow ID should go first in the netlink msg.

OK.

> > @@ -915,8 +980,9 @@ static int ovs_flow_cmd_new(struct sk_buff *skb,
> > struct genl_info *info)
> > 
> >                 error = -ENODEV;
> >                 goto err_unlock_ovs;
> >         
> >         }
> > 
> > +
> > 
> >         /* Check if this is a duplicate flow */
> > 
> > -       flow = ovs_flow_tbl_lookup(&dp->table, &new_flow->unmasked_key);
> > +       flow = ovs_flow_tbl_lookup(&dp->table, &new_flow->key);
> 
> Need to check for ufid table to find duplicate ufid entry here.
 
OK.

> > diff --git a/datapath/flow.h b/datapath/flow.h
> > index 2bbf789..736e0eb 100644
> > --- a/datapath/flow.h
> > +++ b/datapath/flow.h
> > @@ -196,6 +196,13 @@ struct sw_flow_match {
> > 
> >         struct sw_flow_mask *mask;
> >  
> >  };
> > 
> > +struct sw_flow_id {
> > +       struct hlist_node node[2];
> > +       u32 hash;
> > +       u8 *ufid;
> > +       u8 ufid_len;
> > +};
> > +
> 
> Lets make ufid array of size 256, we can reject any key greater than
> this. current patch does not support key greater than 256 anyways.

Ok, that sounds reasonable.

> >  struct sw_flow_actions {
> >  
> >         struct rcu_head rcu;
> >         u32 actions_len;
> > 
> > @@ -212,13 +219,20 @@ struct flow_stats {
> > 
> >  struct sw_flow {
> >  
> >         struct rcu_head rcu;
> > 
> > -       struct hlist_node hash_node[2];
> > -       u32 hash;
> > +       struct {
> > +               struct hlist_node node[2];
> > +               u32 hash;
> > +       } flow_hash;
> 
> This change does not look related to this work.

Right, this is unnecessary leftover from earlier iteration.


> >         int stats_last_writer;          /* NUMA-node id of the last
> >         writer on
> >         
> >                                          * 'stats[0]'.
> >                                          */
> >         
> >         struct sw_flow_key key;
> > 
> > -       struct sw_flow_key unmasked_key;
> > +       bool index_by_ufid;             /* Which of the below that
> > userspace +                                          uses to index this
> > flow. */ +       union {
> > +               struct sw_flow_key unmasked_key;
> > +               struct sw_flow_id ufid;
> > +       } index;
> 
> Rather than storing ufid or unmasked key inside struct flow we can
> keep pointer to these objects, that will save some memory.

OK. Do you still care about the union being there?

> > @@ -818,31 +914,65 @@ static int flow_mask_insert(struct flow_table *tbl,
> > struct sw_flow *flow,
> > 
> >  int ovs_flow_tbl_insert(struct flow_table *table, struct sw_flow *flow,
> >  
> >                         const struct sw_flow_mask *mask)
> >  
> >  {
> > 
> > -       struct table_instance *new_ti = NULL;
> > -       struct table_instance *ti;
> > +       struct table_instance *new_ti = NULL, *new_ufid_ti = NULL;
> > +       struct table_instance *ti, *ufid_ti = NULL;
> > 
> >         int err;
> >         
> >         err = flow_mask_insert(table, flow, mask);
> >         if (err)
> >         
> >                 return err;
> > 
> > -       flow->hash = flow_hash(&flow->key, flow->mask->range.start,
> > -                       flow->mask->range.end);
> > +       flow->flow_hash.hash = flow_hash(&flow->key,
> > flow->mask->range.start, +                                       
> > flow->mask->range.end);
> > 
> >         ti = ovsl_dereference(table->ti);
> >         table_instance_insert(ti, flow);
> >         table->count++;
> > 
> > +       if (flow->index_by_ufid) {
> > +               flow->index.ufid.hash = ufid_hash(&flow->index.ufid);
> > +               ufid_ti = ovsl_dereference(table->ufid_ti);
> > +               ufid_table_instance_insert(ufid_ti, flow);
> > +               table->ufid_count++;
> > +       }
> > 
> >         /* Expand table, if necessary, to make room. */
> >         if (table->count > ti->n_buckets)
> > 
> > -               new_ti = table_instance_expand(ti);
> > +               new_ti = flow_table_expand(ti, false);
> > 
> >         else if (time_after(jiffies, table->last_rehash +
> >         REHASH_INTERVAL))
> > 
> > -               new_ti = table_instance_rehash(ti, ti->n_buckets);
> > +               new_ti = flow_table_rehash(ti, ti->n_buckets, false);
> > +       if (ufid_ti && table->ufid_count > ufid_ti->n_buckets)
> > +               new_ufid_ti = flow_table_expand(ufid_ti, true);
> > 
> >         if (new_ti) {
> >         
> >                 rcu_assign_pointer(table->ti, new_ti);
> > 
> > -               table_instance_destroy(ti, true);
> > +               call_rcu(&ti->rcu, flow_tbl_destroy_rcu_cb);
> > 
> >                 table->last_rehash = jiffies;
> >         
> >         }
> > 
> > +       if (new_ufid_ti) {
> > +               rcu_assign_pointer(table->ufid_ti, new_ufid_ti);
> > +               call_rcu(&ufid_ti->rcu, flow_tbl_destroy_rcu_cb);
> > +       }
> > +       return 0;
> > +}
> 
> Insert function can be simplified by first updating flow-table and
> then updating ufid table.

Sure.


> >  #define OVS_FLOW_ATTR_MAX (__OVS_FLOW_ATTR_MAX - 1)
> >  
> >  /**
> > 
> > + * enum ovs_ufid_attr - Unique identifier types.
> > + *
> > + * @OVS_UFID_ATTR_FLAGS: A 32-bit value specifying changes to the
> > behaviour of + * the current %OVS_FLOW_CMD_* request. Optional for all
> > requests. + * @OVS_UFID_ATTR_ID: A unique identifier for a flow.
> > + */
> > +enum ovs_ufid_attr {
> > +       OVS_UFID_ATTR_UNSPEC,
> > +       OVS_UFID_ATTR_FLAGS,     /* u32 of OVS_UFID_F_* */
> > +       OVS_UFID_ATTR_ID,        /* variable length identifier. */
> > +       __OVS_UFID_ATTR_MAX
> > +};
> > +
> > +#define OVS_UFID_ATTR_MAX (__OVS_UFID_ATTR_MAX - 1)
> > +
> > +/**
> > + * Omit attributes for notifications.
> > + *
> > + * If a datapath request contains an OVS_UFID_F_OMIT_* flag, then the
> > datapath + * may omit the corresponding 'ovs_flow_attr' from the
> > response. + */
> > +#define OVS_UFID_F_OMIT_KEY      (1 << 0)
> > +#define OVS_UFID_F_OMIT_MASK     (1 << 1)
> > +#define OVS_UFID_F_OMIT_ACTIONS  (1 << 2)
> > +
> 
> These flags are related to flow operations. So OVS_UFID_ATTR_FLAGS
> should be part of enum ovs_flow_attr.
> This way we do not need to make UFID nested attr.

OK, I'll shift it out.

Thanks for the review, I'll work on a fresh revision.
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On Wed, Nov 19, 2014 at 4:20 PM, Joe Stringer <joestringer@nicira.com> wrote:
> On Wednesday, November 19, 2014 15:34:24 Pravin Shelar wrote:
>> On Thu, Nov 13, 2014 at 11:17 AM, Joe Stringer <joestringer@nicira.com>
> wrote:
>> > @@ -684,33 +691,43 @@ static size_t ovs_flow_cmd_msg_size(const struct
>> > sw_flow_actions *acts)
>> >
>> >  /* Called with ovs_mutex or RCU read lock. */
>> >  static int ovs_flow_cmd_fill_match(const struct sw_flow *flow,
>> >
>> > -                                  struct sk_buff *skb)
>> > +                                  struct sk_buff *skb, u32 ufid_flags)
>> >
>> >  {
>> >
>> >         struct nlattr *nla;
>> >         int err;
>> >
>> > -       /* Fill flow key. */
>> > -       nla = nla_nest_start(skb, OVS_FLOW_ATTR_KEY);
>> > -       if (!nla)
>> > -               return -EMSGSIZE;
>> > -
>> > -       err = ovs_nla_put_flow(&flow->unmasked_key, &flow->unmasked_key,
>> > skb, -                              false);
>> > -       if (err)
>> > -               return err;
>> > -
>> > -       nla_nest_end(skb, nla);
>> > +       /* Fill flow key. If userspace didn't specify a UFID, then ignore
>> > the +        * OMIT_KEY flag. */
>> > +       if (!(ufid_flags & OVS_UFID_F_OMIT_KEY) ||
>> > +           !flow->index_by_ufid) {
>>
>> I am not sure about this check, userspace needs to send atleast ufid
>> or the unmasked key as id for flow. otherwise we shld flag error. Here
>> we can serialize flow->key.
>> There could be another function which takes care of flow-id
>> serialization where we serialize use ufid or unmasked key as flow id.
>> Lets group ufid and unmasked key together rather than masked key and
>> unmasked key which are not related.
>
> Right, at flow setup time the flow key is always required, but the UFID is
> optional. For most other cases, one of the two most be specified. For flow dump,
> neither is required from userspace, but OMIT_KEY flag may be raised. That's the
> particular case that this logic is trying to catch (dump all flows, including
> those that were set up without UFID - in which case the OMIT_KEY flag doesn't
> make sense, so treat the flag like a request rather than a command).
>

How do you handle overlapping flows without the flow id in dump operation?

> Happy to split the key/identifier out from the mask.
>
>> > @@ -740,6 +757,32 @@ static int ovs_flow_cmd_fill_stats(const struct
>> > sw_flow *flow,
>> >
>> >  }
>> >
>> >  /* Called with ovs_mutex or RCU read lock. */
>> >
>> > +static int ovs_flow_cmd_fill_ufid(const struct sw_flow *flow,
>> > +                                 struct sk_buff *skb)
>> > +{
>> > +       struct nlattr *start;
>> > +       const struct sw_flow_id *sfid;
>> > +
>> > +       if (!flow->index_by_ufid)
>> > +               return 0;
>> > +
>> > +       sfid = &flow->index.ufid;
>> > +       start = nla_nest_start(skb, OVS_FLOW_ATTR_UFID);
>> > +       if (start) {
>> > +               int err;
>> > +
>> > +               err = nla_put(skb, OVS_UFID_ATTR_ID, sfid->ufid_len,
>> > +                             sfid->ufid);
>> > +               if (err)
>> > +                       return err;
>> > +               nla_nest_end(skb, start);
>> > +       } else
>> > +               return -EMSGSIZE;
>> > +
>> > +       return 0;
>> > +}
>> > +
>>
>> Can you change this function according to comments above?
>
> OK.
>
>> > @@ -795,18 +838,24 @@ static int ovs_flow_cmd_fill_info(const struct
>> > sw_flow *flow, int dp_ifindex,
>> >
>> >         ovs_header->dp_ifindex = dp_ifindex;
>> >
>> > -       err = ovs_flow_cmd_fill_match(flow, skb);
>> > +       err = ovs_flow_cmd_fill_match(flow, skb, ufid_flags);
>> >
>> >         if (err)
>> >
>> >                 goto error;
>> >
>> > -       err = ovs_flow_cmd_fill_stats(flow, skb);
>> > +       err = ovs_flow_cmd_fill_ufid(flow, skb);
>> >
>> >         if (err)
>> >
>> >                 goto error;
>>
>> Flow ID should go first in the netlink msg.
>
> OK.
>
>> > @@ -915,8 +980,9 @@ static int ovs_flow_cmd_new(struct sk_buff *skb,
>> > struct genl_info *info)
>> >
>> >                 error = -ENODEV;
>> >                 goto err_unlock_ovs;
>> >
>> >         }
>> >
>> > +
>> >
>> >         /* Check if this is a duplicate flow */
>> >
>> > -       flow = ovs_flow_tbl_lookup(&dp->table, &new_flow->unmasked_key);
>> > +       flow = ovs_flow_tbl_lookup(&dp->table, &new_flow->key);
>>
>> Need to check for ufid table to find duplicate ufid entry here.
>
> OK.
>
>> > diff --git a/datapath/flow.h b/datapath/flow.h
>> > index 2bbf789..736e0eb 100644
>> > --- a/datapath/flow.h
>> > +++ b/datapath/flow.h
>> > @@ -196,6 +196,13 @@ struct sw_flow_match {
>> >
>> >         struct sw_flow_mask *mask;
>> >
>> >  };
>> >
>> > +struct sw_flow_id {
>> > +       struct hlist_node node[2];
>> > +       u32 hash;
>> > +       u8 *ufid;
>> > +       u8 ufid_len;
>> > +};
>> > +
>>
>> Lets make ufid array of size 256, we can reject any key greater than
>> this. current patch does not support key greater than 256 anyways.
>
> Ok, that sounds reasonable.
>
>> >  struct sw_flow_actions {
>> >
>> >         struct rcu_head rcu;
>> >         u32 actions_len;
>> >
>> > @@ -212,13 +219,20 @@ struct flow_stats {
>> >
>> >  struct sw_flow {
>> >
>> >         struct rcu_head rcu;
>> >
>> > -       struct hlist_node hash_node[2];
>> > -       u32 hash;
>> > +       struct {
>> > +               struct hlist_node node[2];
>> > +               u32 hash;
>> > +       } flow_hash;
>>
>> This change does not look related to this work.
>
> Right, this is unnecessary leftover from earlier iteration.
>
>
>> >         int stats_last_writer;          /* NUMA-node id of the last
>> >         writer on
>> >
>> >                                          * 'stats[0]'.
>> >                                          */
>> >
>> >         struct sw_flow_key key;
>> >
>> > -       struct sw_flow_key unmasked_key;
>> > +       bool index_by_ufid;             /* Which of the below that
>> > userspace +                                          uses to index this
>> > flow. */ +       union {
>> > +               struct sw_flow_key unmasked_key;
>> > +               struct sw_flow_id ufid;
>> > +       } index;
>>
>> Rather than storing ufid or unmasked key inside struct flow we can
>> keep pointer to these objects, that will save some memory.
>
> OK. Do you still care about the union being there?
>
Lets keep both pointer so that we can get rid of the index_by_fid flag.


>> > @@ -818,31 +914,65 @@ static int flow_mask_insert(struct flow_table *tbl,
>> > struct sw_flow *flow,
>> >
>> >  int ovs_flow_tbl_insert(struct flow_table *table, struct sw_flow *flow,
>> >
>> >                         const struct sw_flow_mask *mask)
>> >
>> >  {
>> >
>> > -       struct table_instance *new_ti = NULL;
>> > -       struct table_instance *ti;
>> > +       struct table_instance *new_ti = NULL, *new_ufid_ti = NULL;
>> > +       struct table_instance *ti, *ufid_ti = NULL;
>> >
>> >         int err;
>> >
>> >         err = flow_mask_insert(table, flow, mask);
>> >         if (err)
>> >
>> >                 return err;
>> >
>> > -       flow->hash = flow_hash(&flow->key, flow->mask->range.start,
>> > -                       flow->mask->range.end);
>> > +       flow->flow_hash.hash = flow_hash(&flow->key,
>> > flow->mask->range.start, +
>> > flow->mask->range.end);
>> >
>> >         ti = ovsl_dereference(table->ti);
>> >         table_instance_insert(ti, flow);
>> >         table->count++;
>> >
>> > +       if (flow->index_by_ufid) {
>> > +               flow->index.ufid.hash = ufid_hash(&flow->index.ufid);
>> > +               ufid_ti = ovsl_dereference(table->ufid_ti);
>> > +               ufid_table_instance_insert(ufid_ti, flow);
>> > +               table->ufid_count++;
>> > +       }
>> >
>> >         /* Expand table, if necessary, to make room. */
>> >         if (table->count > ti->n_buckets)
>> >
>> > -               new_ti = table_instance_expand(ti);
>> > +               new_ti = flow_table_expand(ti, false);
>> >
>> >         else if (time_after(jiffies, table->last_rehash +
>> >         REHASH_INTERVAL))
>> >
>> > -               new_ti = table_instance_rehash(ti, ti->n_buckets);
>> > +               new_ti = flow_table_rehash(ti, ti->n_buckets, false);
>> > +       if (ufid_ti && table->ufid_count > ufid_ti->n_buckets)
>> > +               new_ufid_ti = flow_table_expand(ufid_ti, true);
>> >
>> >         if (new_ti) {
>> >
>> >                 rcu_assign_pointer(table->ti, new_ti);
>> >
>> > -               table_instance_destroy(ti, true);
>> > +               call_rcu(&ti->rcu, flow_tbl_destroy_rcu_cb);
>> >
>> >                 table->last_rehash = jiffies;
>> >
>> >         }
>> >
>> > +       if (new_ufid_ti) {
>> > +               rcu_assign_pointer(table->ufid_ti, new_ufid_ti);
>> > +               call_rcu(&ufid_ti->rcu, flow_tbl_destroy_rcu_cb);
>> > +       }
>> > +       return 0;
>> > +}
>>
>> Insert function can be simplified by first updating flow-table and
>> then updating ufid table.
>
> Sure.
>
>
>> >  #define OVS_FLOW_ATTR_MAX (__OVS_FLOW_ATTR_MAX - 1)
>> >
>> >  /**
>> >
>> > + * enum ovs_ufid_attr - Unique identifier types.
>> > + *
>> > + * @OVS_UFID_ATTR_FLAGS: A 32-bit value specifying changes to the
>> > behaviour of + * the current %OVS_FLOW_CMD_* request. Optional for all
>> > requests. + * @OVS_UFID_ATTR_ID: A unique identifier for a flow.
>> > + */
>> > +enum ovs_ufid_attr {
>> > +       OVS_UFID_ATTR_UNSPEC,
>> > +       OVS_UFID_ATTR_FLAGS,     /* u32 of OVS_UFID_F_* */
>> > +       OVS_UFID_ATTR_ID,        /* variable length identifier. */
>> > +       __OVS_UFID_ATTR_MAX
>> > +};
>> > +
>> > +#define OVS_UFID_ATTR_MAX (__OVS_UFID_ATTR_MAX - 1)
>> > +
>> > +/**
>> > + * Omit attributes for notifications.
>> > + *
>> > + * If a datapath request contains an OVS_UFID_F_OMIT_* flag, then the
>> > datapath + * may omit the corresponding 'ovs_flow_attr' from the
>> > response. + */
>> > +#define OVS_UFID_F_OMIT_KEY      (1 << 0)
>> > +#define OVS_UFID_F_OMIT_MASK     (1 << 1)
>> > +#define OVS_UFID_F_OMIT_ACTIONS  (1 << 2)
>> > +
>>
>> These flags are related to flow operations. So OVS_UFID_ATTR_FLAGS
>> should be part of enum ovs_flow_attr.
>> This way we do not need to make UFID nested attr.
>
> OK, I'll shift it out.
>
> Thanks for the review, I'll work on a fresh revision.
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On Wednesday, November 19, 2014 16:39:20 Pravin Shelar wrote:
> On Wed, Nov 19, 2014 at 4:20 PM, Joe Stringer <joestringer@nicira.com> 
wrote:
> > On Wednesday, November 19, 2014 15:34:24 Pravin Shelar wrote:
> >> On Thu, Nov 13, 2014 at 11:17 AM, Joe Stringer <joestringer@nicira.com>
> > 
> > wrote:
> >> > @@ -684,33 +691,43 @@ static size_t ovs_flow_cmd_msg_size(const struct
> >> > sw_flow_actions *acts)
> >> > 
> >> >  /* Called with ovs_mutex or RCU read lock. */
> >> >  static int ovs_flow_cmd_fill_match(const struct sw_flow *flow,
> >> > 
> >> > -                                  struct sk_buff *skb)
> >> > +                                  struct sk_buff *skb, u32
> >> > ufid_flags)
> >> > 
> >> >  {
> >> >  
> >> >         struct nlattr *nla;
> >> >         int err;
> >> > 
> >> > -       /* Fill flow key. */
> >> > -       nla = nla_nest_start(skb, OVS_FLOW_ATTR_KEY);
> >> > -       if (!nla)
> >> > -               return -EMSGSIZE;
> >> > -
> >> > -       err = ovs_nla_put_flow(&flow->unmasked_key,
> >> > &flow->unmasked_key, skb, -                              false);
> >> > -       if (err)
> >> > -               return err;
> >> > -
> >> > -       nla_nest_end(skb, nla);
> >> > +       /* Fill flow key. If userspace didn't specify a UFID, then
> >> > ignore the +        * OMIT_KEY flag. */
> >> > +       if (!(ufid_flags & OVS_UFID_F_OMIT_KEY) ||
> >> > +           !flow->index_by_ufid) {
> >> 
> >> I am not sure about this check, userspace needs to send atleast ufid
> >> or the unmasked key as id for flow. otherwise we shld flag error. Here
> >> we can serialize flow->key.
> >> There could be another function which takes care of flow-id
> >> serialization where we serialize use ufid or unmasked key as flow id.
> >> Lets group ufid and unmasked key together rather than masked key and
> >> unmasked key which are not related.
> > 
> > Right, at flow setup time the flow key is always required, but the UFID
> > is optional. For most other cases, one of the two most be specified. For
> > flow dump, neither is required from userspace, but OMIT_KEY flag may be
> > raised. That's the particular case that this logic is trying to catch
> > (dump all flows, including those that were set up without UFID - in
> > which case the OMIT_KEY flag doesn't make sense, so treat the flag like
> > a request rather than a command).
> 
> How do you handle overlapping flows without the flow id in dump operation?

In userspace? revalidators will dump flows, then if the flow-key is exactly the 
same as another flow then they will be hashed to the same udpif_key and the 
second flow will be ignored each dump. So, stats may get messed up. If they 
differ but overlap, they will hash to different udpif_keys and stats tracked 
separately. Revalidator won't check the validity of overlapping flows until the 
next change to ofproto-dpif.
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On 19 November 2014 15:34, Pravin Shelar <pshelar@nicira.com> wrote:
> On Thu, Nov 13, 2014 at 11:17 AM, Joe Stringer <joestringer@nicira.com> wrote:
>> @@ -684,33 +691,43 @@ static size_t ovs_flow_cmd_msg_size(const struct sw_flow_actions *acts)
>>
>>  /* Called with ovs_mutex or RCU read lock. */
>>  static int ovs_flow_cmd_fill_match(const struct sw_flow *flow,
>> -                                  struct sk_buff *skb)
>> +                                  struct sk_buff *skb, u32 ufid_flags)
>>  {
>>         struct nlattr *nla;
>>         int err;
>>
>> -       /* Fill flow key. */
>> -       nla = nla_nest_start(skb, OVS_FLOW_ATTR_KEY);
>> -       if (!nla)
>> -               return -EMSGSIZE;
>> -
>> -       err = ovs_nla_put_flow(&flow->unmasked_key, &flow->unmasked_key, skb,
>> -                              false);
>> -       if (err)
>> -               return err;
>> -
>> -       nla_nest_end(skb, nla);
>> +       /* Fill flow key. If userspace didn't specify a UFID, then ignore the
>> +        * OMIT_KEY flag. */
>> +       if (!(ufid_flags & OVS_UFID_F_OMIT_KEY) ||
>> +           !flow->index_by_ufid) {
>
> I am not sure about this check, userspace needs to send atleast ufid
> or the unmasked key as id for flow. otherwise we shld flag error. Here
> we can serialize flow->key.
> There could be another function which takes care of flow-id
> serialization where we serialize use ufid or unmasked key as flow id.
> Lets group ufid and unmasked key together rather than masked key and
> unmasked key which are not related.

Let me start from scratch and see if this is what you're saying.

fill_id() would serialize the UFID or unmasked key if UFID is not available.
fill_key() would serialize the masked key if !(ufid_flags &
OVS_UFID_F_OMIT_KEY) and UFID was provided (but not when the UFID is
missing).
fill_mask() would serialize the mask if !(ufid_flags & OVS_UFID_F_OMIT_MASK).

I see key and id as related, because the flow_key serves as both the
"match" and the "id" in the non-ufid case, so we need to know the same
piece of information in both functions to ensure we don't serialize
the key twice.
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On Thu, Nov 20, 2014 at 4:33 PM, Joe Stringer <joestringer@nicira.com> wrote:
> On 19 November 2014 15:34, Pravin Shelar <pshelar@nicira.com> wrote:
>> On Thu, Nov 13, 2014 at 11:17 AM, Joe Stringer <joestringer@nicira.com> wrote:
>>> @@ -684,33 +691,43 @@ static size_t ovs_flow_cmd_msg_size(const struct sw_flow_actions *acts)
>>>
>>>  /* Called with ovs_mutex or RCU read lock. */
>>>  static int ovs_flow_cmd_fill_match(const struct sw_flow *flow,
>>> -                                  struct sk_buff *skb)
>>> +                                  struct sk_buff *skb, u32 ufid_flags)
>>>  {
>>>         struct nlattr *nla;
>>>         int err;
>>>
>>> -       /* Fill flow key. */
>>> -       nla = nla_nest_start(skb, OVS_FLOW_ATTR_KEY);
>>> -       if (!nla)
>>> -               return -EMSGSIZE;
>>> -
>>> -       err = ovs_nla_put_flow(&flow->unmasked_key, &flow->unmasked_key, skb,
>>> -                              false);
>>> -       if (err)
>>> -               return err;
>>> -
>>> -       nla_nest_end(skb, nla);
>>> +       /* Fill flow key. If userspace didn't specify a UFID, then ignore the
>>> +        * OMIT_KEY flag. */
>>> +       if (!(ufid_flags & OVS_UFID_F_OMIT_KEY) ||
>>> +           !flow->index_by_ufid) {
>>
>> I am not sure about this check, userspace needs to send atleast ufid
>> or the unmasked key as id for flow. otherwise we shld flag error. Here
>> we can serialize flow->key.
>> There could be another function which takes care of flow-id
>> serialization where we serialize use ufid or unmasked key as flow id.
>> Lets group ufid and unmasked key together rather than masked key and
>> unmasked key which are not related.
>
> Let me start from scratch and see if this is what you're saying.
>
> fill_id() would serialize the UFID or unmasked key if UFID is not available.
> fill_key() would serialize the masked key if !(ufid_flags &
> OVS_UFID_F_OMIT_KEY) and UFID was provided (but not when the UFID is
> missing).
> fill_mask() would serialize the mask if !(ufid_flags & OVS_UFID_F_OMIT_MASK).
>
> I see key and id as related, because the flow_key serves as both the
> "match" and the "id" in the non-ufid case, so we need to know the same
> piece of information in both functions to ensure we don't serialize
> the key twice.

Lets follow new model where ID and key are two separate attributes. I
agree we also need to check for ufid in key serialization function to
handle compatibility code. Keeping masked and unmasked key separate is
easier to understand.
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