From 9e4e948a3edafd2b7f4dc14c395e146ffd0d9611 Mon Sep 17 00:00:00 2001 From: Julian Anastasov Date: Wed, 9 Oct 2013 09:24:27 +0300 Subject: [PATCH] ipvs: avoid rcu_barrier during netns cleanup commit 578bc3ef1e473a ("ipvs: reorganize dest trash") added rcu_barrier() on cleanup to wait dest users and schedulers like LBLC and LBLCR to put their last dest reference. Using rcu_barrier with many namespaces is problematic. Trying to fix it by freeing dest with kfree_rcu is not a solution, RCU callbacks can run in parallel and execution order is random. Fix it by creating new function ip_vs_dest_put_and_free() which is heavier than ip_vs_dest_put(). We will use it just for schedulers like LBLC, LBLCR that can delay their dest release. By default, dests reference is above 0 if they are present in service and it is 0 when deleted but still in trash list. Change the dest trash code to use ip_vs_dest_put_and_free(), so that refcnt -1 can be used for freeing. As result, such checks remain in slow path and the rcu_barrier() from netns cleanup can be removed. Signed-off-by: Julian Anastasov Signed-off-by: Simon Horman --- include/net/ip_vs.h | 6 ++++++ net/netfilter/ipvs/ip_vs_ctl.c | 6 +----- net/netfilter/ipvs/ip_vs_lblc.c | 2 +- net/netfilter/ipvs/ip_vs_lblcr.c | 2 +- 4 files changed, 9 insertions(+), 7 deletions(-) diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h index 1c2e1b9f6b86..cd7275f9c463 100644 --- a/include/net/ip_vs.h +++ b/include/net/ip_vs.h @@ -1442,6 +1442,12 @@ static inline void ip_vs_dest_put(struct ip_vs_dest *dest) atomic_dec(&dest->refcnt); } +static inline void ip_vs_dest_put_and_free(struct ip_vs_dest *dest) +{ + if (atomic_dec_return(&dest->refcnt) < 0) + kfree(dest); +} + /* * IPVS sync daemon data and function prototypes * (from ip_vs_sync.c) diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c index a3df9bddc4f7..62786a495cea 100644 --- a/net/netfilter/ipvs/ip_vs_ctl.c +++ b/net/netfilter/ipvs/ip_vs_ctl.c @@ -704,7 +704,7 @@ static void ip_vs_dest_free(struct ip_vs_dest *dest) __ip_vs_dst_cache_reset(dest); __ip_vs_svc_put(svc, false); free_percpu(dest->stats.cpustats); - kfree(dest); + ip_vs_dest_put_and_free(dest); } /* @@ -3820,10 +3820,6 @@ void __net_exit ip_vs_control_net_cleanup(struct net *net) { struct netns_ipvs *ipvs = net_ipvs(net); - /* Some dest can be in grace period even before cleanup, we have to - * defer ip_vs_trash_cleanup until ip_vs_dest_wait_readers is called. - */ - rcu_barrier(); ip_vs_trash_cleanup(net); ip_vs_stop_estimator(net, &ipvs->tot_stats); ip_vs_control_net_cleanup_sysctl(net); diff --git a/net/netfilter/ipvs/ip_vs_lblc.c b/net/netfilter/ipvs/ip_vs_lblc.c index eff13c94498e..ca056a331e60 100644 --- a/net/netfilter/ipvs/ip_vs_lblc.c +++ b/net/netfilter/ipvs/ip_vs_lblc.c @@ -136,7 +136,7 @@ static void ip_vs_lblc_rcu_free(struct rcu_head *head) struct ip_vs_lblc_entry, rcu_head); - ip_vs_dest_put(en->dest); + ip_vs_dest_put_and_free(en->dest); kfree(en); } diff --git a/net/netfilter/ipvs/ip_vs_lblcr.c b/net/netfilter/ipvs/ip_vs_lblcr.c index 0b8550089a2e..3f21a2f47de1 100644 --- a/net/netfilter/ipvs/ip_vs_lblcr.c +++ b/net/netfilter/ipvs/ip_vs_lblcr.c @@ -130,7 +130,7 @@ static void ip_vs_lblcr_elem_rcu_free(struct rcu_head *head) struct ip_vs_dest_set_elem *e; e = container_of(head, struct ip_vs_dest_set_elem, rcu_head); - ip_vs_dest_put(e->dest); + ip_vs_dest_put_and_free(e->dest); kfree(e); } -- 2.34.1