[{"id":1772738,"web_url":"http://patchwork.ozlabs.org/comment/1772738/","msgid":"<54cb367e-3769-ce9f-27dc-e08ee710bd98@cumulusnetworks.com>","list_archive_url":null,"date":"2017-09-21T11:56:59","subject":"Re: [patch net-next 02/12] ipmr: Add reference count to MFC entries","submitter":{"id":66448,"url":"http://patchwork.ozlabs.org/api/people/66448/","name":"Nikolay Aleksandrov","email":"nikolay@cumulusnetworks.com"},"content":"On 21/09/17 09:43, Jiri Pirko wrote:\n> From: Yotam Gigi \n> \n> Next commits will introduce MFC notifications through the atomic\n> fib_notification chain, thus allowing modules to be aware of MFC entries.\n> \n> Due to the fact that modules may need to hold a reference to an MFC entry,\n> add reference count to MFC entries to prevent them from being freed while\n> these modules use them.\n> \n> The reference counting is done only on resolved MFC entries currently.\n> \n> Signed-off-by: Yotam Gigi \n> Reviewed-by: Ido Schimmel \n> Signed-off-by: Jiri Pirko \n> ---\n> include/linux/mroute.h | 20 ++++++++++++++++++++\n> net/ipv4/ipmr.c | 8 +++++---\n> 2 files changed, 25 insertions(+), 3 deletions(-)\n> \n> diff --git a/include/linux/mroute.h b/include/linux/mroute.h\n> index d7f6333..2f88e3d 100644\n> --- a/include/linux/mroute.h\n> +++ b/include/linux/mroute.h\n> @@ -138,6 +138,7 @@ struct mfc_cache {\n> \t\t\tunsigned long wrong_if;\n> \t\t\tunsigned long lastuse;\n> \t\t\tunsigned char ttls[MAXVIFS];\n> +\t\t\trefcount_t refcount;\n\nThere's a struct comment above that has a short description for each entry,\nI know it seems redundant, but could you please add one for this ?\n\n> \t\t} res;\n> \t} mfc_un;\n> \tstruct list_head list;\n> @@ -148,4 +149,23 @@ struct rtmsg;\n> int ipmr_get_route(struct net *net, struct sk_buff *skb,\n> \t\t __be32 saddr, __be32 daddr,\n> \t\t struct rtmsg *rtm, u32 portid);\n> +\n> +#ifdef CONFIG_IP_MROUTE\n> +void ipmr_cache_free(struct mfc_cache *mfc_cache);\n> +#else\n> +static inline void ipmr_cache_free(struct mfc_cache *mfc_cache)\n> +{\n> +}\n> +#endif\n> +\n> +static inline void ipmr_cache_put(struct mfc_cache *c)\n> +{\n> +\tif (refcount_dec_and_test(&c->mfc_un.res.refcount))\n> +\t\tipmr_cache_free(c);\n> +}\n> +static inline void ipmr_cache_hold(struct mfc_cache *c)\n> +{\n> +\trefcount_inc(&c->mfc_un.res.refcount);\n> +}\n> +\n> #endif\n> diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c\n> index c9b3e6e..86dc5f9 100644\n> --- a/net/ipv4/ipmr.c\n> +++ b/net/ipv4/ipmr.c\n> @@ -652,10 +652,11 @@ static void ipmr_cache_free_rcu(struct rcu_head *head)\n> \tkmem_cache_free(mrt_cachep, c);\n> }\n> \n> -static inline void ipmr_cache_free(struct mfc_cache *c)\n> +void ipmr_cache_free(struct mfc_cache *c)\n> {\n> \tcall_rcu(&c->rcu, ipmr_cache_free_rcu);\n> }\n> +EXPORT_SYMBOL(ipmr_cache_free);\n> \n> /* Destroy an unresolved cache entry, killing queued skbs\n> * and reporting error to netlink readers.\n> @@ -949,6 +950,7 @@ static struct mfc_cache *ipmr_cache_alloc(void)\n> \tif (c) {\n> \t\tc->mfc_un.res.last_assert = jiffies - MFC_ASSERT_THRESH - 1;\n> \t\tc->mfc_un.res.minvif = MAXVIFS;\n> +\t\trefcount_set(&c->mfc_un.res.refcount, 1);\n> \t}\n> \treturn c;\n> }\n> @@ -1162,7 +1164,7 @@ static int ipmr_mfc_delete(struct mr_table *mrt, struct mfcctl *mfc, int parent)\n> \trhltable_remove(&mrt->mfc_hash, &c->mnode, ipmr_rht_params);\n> \tlist_del_rcu(&c->list);\n> \tmroute_netlink_event(mrt, c, RTM_DELROUTE);\n> -\tipmr_cache_free(c);\n> +\tipmr_cache_put(c);\n> \n> \treturn 0;\n> }\n> @@ -1264,7 +1266,7 @@ static void mroute_clean_tables(struct mr_table *mrt, bool all)\n> \t\trhltable_remove(&mrt->mfc_hash, &c->mnode, ipmr_rht_params);\n> \t\tlist_del_rcu(&c->list);\n> \t\tmroute_netlink_event(mrt, c, RTM_DELROUTE);\n> -\t\tipmr_cache_free(c);\n> +\t\tipmr_cache_put(c);\n> \t}\n> \n> \tif (atomic_read(&mrt->cache_resolve_queue_len) != 0) {\n>","headers":{"Return-Path":"","X-Original-To":"patchwork-incoming@ozlabs.org","Delivered-To":"patchwork-incoming@ozlabs.org","Authentication-Results":["ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=vger.kernel.org\n\t(client-ip=209.132.180.67; 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