diff mbox series

[ovs-dev,v12,08/11] netdev-offload-tc: Introduce group ID management API

Message ID 20210127062344.194230-9-cmi@nvidia.com
State New
Headers show
Series Add offload support for sFlow | expand

Commit Message

Chris Mi Jan. 27, 2021, 6:23 a.m. UTC
When offloading sample action to TC, userspace creates a unique ID
to map sFlow action and tunnel info and passes this ID to kernel instead
of the sFlow info. psample will send this ID and sampled packet to
userspace. Using the ID, userspace can recover the sFlow info and send
sampled packet to the right sFlow monitoring host.

Signed-off-by: Chris Mi <cmi@nvidia.com>
Reviewed-by: Eli Britstein <elibr@nvidia.com>
---
 lib/netdev-offload-tc.c | 274 +++++++++++++++++++++++++++++++++++++++-
 lib/tc.h                |   1 +
 2 files changed, 273 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/lib/netdev-offload-tc.c b/lib/netdev-offload-tc.c
index 2b08ea55e..969a64562 100644
--- a/lib/netdev-offload-tc.c
+++ b/lib/netdev-offload-tc.c
@@ -39,6 +39,7 @@ 
 #include "unaligned.h"
 #include "util.h"
 #include "dpif-provider.h"
+#include "cmap.h"
 
 VLOG_DEFINE_THIS_MODULE(netdev_offload_tc);
 
@@ -57,6 +58,264 @@  struct netlink_field {
     int size;
 };
 
+/* This maps a psample group ID to struct dpif_sflow_attr for sFlow */
+struct sgid_node {
+    struct ovs_list exp_node OVS_GUARDED;
+    struct cmap_node metadata_node;
+    struct cmap_node id_node;
+    struct ovs_refcount refcount;
+    uint32_t hash;
+    uint32_t id;
+    const struct dpif_sflow_attr sflow;
+};
+
+static struct ovs_rwlock sgid_rwlock = OVS_RWLOCK_INITIALIZER;
+
+static long long int sgid_last_run OVS_GUARDED_BY(sgid_rwlock);
+
+static struct cmap sgid_map = CMAP_INITIALIZER;
+static struct cmap sgid_metadata_map = CMAP_INITIALIZER;
+
+static struct ovs_list sgid_expiring OVS_GUARDED_BY(sgid_rwlock)
+    = OVS_LIST_INITIALIZER(&sgid_expiring);
+static struct ovs_list sgid_expired OVS_GUARDED_BY(sgid_rwlock)
+    = OVS_LIST_INITIALIZER(&sgid_expired);
+
+static uint32_t next_sample_group_id OVS_GUARDED_BY(sgid_rwlock) = 1;
+
+#define SGID_RUN_INTERVAL   250     /* msec */
+
+static void
+sgid_node_free(struct sgid_node *node)
+{
+    free(node->sflow.tunnel);
+    free(CONST_CAST(void *, node->sflow.sflow));
+    free(node->sflow.userdata);
+    free(node);
+}
+
+static void
+sgid_cleanup(void)
+{
+    long long int now = time_msec();
+    struct sgid_node *node;
+
+    /* Do maintenance at most 4 times / sec. */
+    ovs_rwlock_rdlock(&sgid_rwlock);
+    if (now - sgid_last_run < SGID_RUN_INTERVAL) {
+        ovs_rwlock_unlock(&sgid_rwlock);
+        return;
+    }
+    ovs_rwlock_unlock(&sgid_rwlock);
+
+    ovs_rwlock_wrlock(&sgid_rwlock);
+    sgid_last_run = now;
+
+    LIST_FOR_EACH_POP (node, exp_node, &sgid_expired) {
+        cmap_remove(&sgid_map, &node->id_node, node->id);
+        ovsrcu_postpone(sgid_node_free, node);
+    }
+
+    if (!ovs_list_is_empty(&sgid_expiring)) {
+        /* 'sgid_expired' is now empty, move nodes in
+         * 'sgid_expiring' to it. */
+        ovs_list_splice(&sgid_expired,
+                        ovs_list_front(&sgid_expiring),
+                        &sgid_expiring);
+    }
+    ovs_rwlock_unlock(&sgid_rwlock);
+}
+
+/* Lockless RCU protected lookup.  If node is needed accross RCU quiescent
+ * state, caller should copy the contents. */
+static const struct sgid_node *
+sgid_find(uint32_t id)
+{
+    const struct cmap_node *node = cmap_find(&sgid_map, id);
+
+    return node ? CONTAINER_OF(node, const struct sgid_node, id_node) : NULL;
+}
+
+static uint32_t
+dpif_sflow_attr_hash(const struct dpif_sflow_attr *sflow)
+{
+    uint32_t hash = hash_bytes(sflow->sflow, sflow->sflow->nla_len, 0);
+
+    if (sflow->tunnel) {
+        hash = hash_bytes(sflow->tunnel, sizeof *sflow->tunnel, hash);
+    }
+    return hash;
+}
+
+static bool
+dpif_sflow_attr_equal(const struct dpif_sflow_attr *a,
+                      const struct dpif_sflow_attr *b)
+{
+    if (a->sflow->nla_len != b->sflow->nla_len
+        || memcmp(a->sflow, b->sflow, a->sflow->nla_len)) {
+        return false;
+    }
+    if (!a->tunnel && !b->tunnel) {
+        return true;
+    }
+    if (a->tunnel && b->tunnel) {
+        return !memcmp(a->tunnel, b->tunnel, sizeof *a->tunnel);
+    }
+
+    return false;
+}
+
+/* Lockless RCU protected lookup.  If node is needed accross RCU quiescent
+ * state, caller should take a reference. */
+static struct sgid_node *
+sgid_find_equal(const struct dpif_sflow_attr *target, uint32_t hash)
+{
+    struct sgid_node *node;
+
+    CMAP_FOR_EACH_WITH_HASH (node, metadata_node, hash, &sgid_metadata_map) {
+        if (dpif_sflow_attr_equal(&node->sflow, target)) {
+            return node;
+        }
+    }
+    return NULL;
+}
+
+static struct sgid_node *
+sgid_ref_equal(const struct dpif_sflow_attr *target, uint32_t hash)
+{
+    struct sgid_node *node;
+
+    do {
+        node = sgid_find_equal(target, hash);
+        /* Try again if the node was released before we get the reference. */
+    } while (node && !ovs_refcount_try_ref_rcu(&node->refcount));
+
+    return node;
+}
+
+static void
+dpif_sflow_attr_clone(struct dpif_sflow_attr *new,
+                      const struct dpif_sflow_attr *old)
+{
+    new->sflow = xmemdup(old->sflow, old->sflow->nla_len);
+    new->userdata = xmemdup(old->userdata, old->userdata_len);
+    new->userdata_len = old->userdata_len;
+    new->tunnel = old->tunnel
+                  ? xmemdup(old->tunnel, sizeof *old->tunnel)
+                  : NULL;
+}
+
+/* We use the id as the hash value, which works due to cmap internal rehashing.
+ * We also only insert nodes with unique IDs, so all possible hash collisions
+ * remain internal to the cmap. */
+static struct sgid_node *
+sgid_find__(uint32_t id)
+    OVS_REQUIRES(sgid_rwlock)
+{
+    struct cmap_node *node = cmap_find_protected(&sgid_map, id);
+
+    return node ? CONTAINER_OF(node, struct sgid_node, id_node) : NULL;
+}
+
+/* Allocate a unique group id for the given set of flow metadata. The id
+ * space is 2^^32, but if looping too many times, we still can't find a
+ * free one, that means something is wrong, return NULL.
+ */
+#define SGID_ALLOC_RETRY_MAX 8192
+static struct sgid_node *
+sgid_alloc__(const struct dpif_sflow_attr *sflow, uint32_t hash)
+{
+    struct sgid_node *node = xzalloc(sizeof *node);
+    int i = 0;
+
+    node->hash = hash;
+    ovs_refcount_init(&node->refcount);
+    dpif_sflow_attr_clone(CONST_CAST(struct dpif_sflow_attr *, &node->sflow),
+                          sflow);
+
+    ovs_rwlock_wrlock(&sgid_rwlock);
+    for (;;) {
+        node->id = next_sample_group_id++;
+        if (OVS_UNLIKELY(!node->id)) {
+            next_sample_group_id = 1;
+            node->id = next_sample_group_id++;
+        }
+        /* Find if the id is free. */
+        if (OVS_LIKELY(!sgid_find__(node->id))) {
+            break;
+        }
+        if (++i == SGID_ALLOC_RETRY_MAX) {
+            VLOG_ERR("%s: Can't find a free group ID after %d retries",
+                     __func__, i);
+            ovs_rwlock_unlock(&sgid_rwlock);
+            sgid_node_free(node);
+            return NULL;
+        }
+    }
+    cmap_insert(&sgid_map, &node->id_node, node->id);
+    cmap_insert(&sgid_metadata_map, &node->metadata_node, node->hash);
+    ovs_rwlock_unlock(&sgid_rwlock);
+    return node;
+}
+
+/* Allocate a unique group id for the given set of flow metadata and
+   optional actions. */
+static uint32_t
+sgid_alloc_ctx(const struct dpif_sflow_attr *sflow)
+{
+    uint32_t hash = dpif_sflow_attr_hash(sflow);
+    struct sgid_node *node = sgid_ref_equal(sflow, hash);
+
+    if (!node) {
+        node = sgid_alloc__(sflow, hash);
+    }
+
+    return node ? node->id : 0;
+}
+
+static void
+sgid_node_unref(const struct sgid_node *node_)
+    OVS_EXCLUDED(sgid_rwlock)
+{
+    struct sgid_node *node = CONST_CAST(struct sgid_node *, node_);
+
+    ovs_rwlock_wrlock(&sgid_rwlock);
+    if (node && ovs_refcount_unref(&node->refcount) == 1) {
+        /* Prevent re-use of this node by removing the node from
+         * sgid_metadata_map' */
+        cmap_remove(&sgid_metadata_map, &node->metadata_node, node->hash);
+        /* We keep the node in the 'sgid_map' so that it can be found as
+         * long as it lingers, and add it to the 'sgid_expiring' list. */
+        ovs_list_insert(&sgid_expiring, &node->exp_node);
+    }
+    ovs_rwlock_unlock(&sgid_rwlock);
+}
+
+static void
+sgid_free(uint32_t id)
+{
+    const struct sgid_node *node;
+
+    if (!id) {
+        return;
+    }
+
+    node = sgid_find(id);
+    if (node) {
+        sgid_node_unref(node);
+    } else {
+        VLOG_ERR("%s: Freeing nonexistent group ID: %"PRIu32, __func__, id);
+    }
+}
+
+static int
+del_filter_and_sgid(struct tcf_id *id)
+{
+    sgid_free(id->sample_group_id);
+    id->sample_group_id = 0;
+    return tc_del_filter(id);
+}
+
 static bool
 is_internal_port(const char *type)
 {
@@ -199,7 +458,7 @@  del_filter_and_ufid_mapping(struct tcf_id *id, const ovs_u128 *ufid)
 {
     int err;
 
-    err = tc_del_filter(id);
+    err = del_filter_and_sgid(id);
     if (!err) {
         del_ufid_tc_mapping(ufid);
     }
@@ -358,7 +617,7 @@  netdev_tc_flow_flush(struct netdev *netdev)
             continue;
         }
 
-        err = tc_del_filter(&data->id);
+        err = del_filter_and_sgid(&data->id);
         if (!err) {
             del_ufid_tc_mapping_unlocked(&data->ufid);
         }
@@ -398,6 +657,12 @@  netdev_tc_flow_dump_create(struct netdev *netdev,
 
     *dump_out = dump;
 
+    /* Cleanup the sFlow group ID nodes in sgid_expired list.
+     * In order to avoid creating a dedicated thread to do it, put it in
+     * the revalidator thread.
+     */
+    sgid_cleanup();
+
     return 0;
 }
 
@@ -1797,6 +2062,11 @@  netdev_tc_flow_put(struct netdev *netdev, struct match *match,
             action->type = TC_ACT_GOTO;
             action->chain = 0;  /* 0 is reserved and not used by recirc. */
             flower.action_count++;
+        } else if (nl_attr_type(nla) == OVS_ACTION_ATTR_SAMPLE) {
+            struct dpif_sflow_attr sflow_attr;
+
+            memset(&sflow_attr, 0, sizeof sflow_attr);
+            sgid_alloc_ctx(&sflow_attr);
         } else {
             VLOG_DBG_RL(&rl, "unsupported put action type: %d",
                         nl_attr_type(nla));
diff --git a/lib/tc.h b/lib/tc.h
index 281231c0d..8394d2342 100644
--- a/lib/tc.h
+++ b/lib/tc.h
@@ -273,6 +273,7 @@  struct tcf_id {
     uint32_t chain;
     uint16_t prio;
     uint32_t handle;
+    uint32_t sample_group_id;
 };
 
 static inline struct tcf_id