Thanks Julian.
Pablo, could you merge net-next into nf-next so that
I can apply this patch on top of the later?
In particular I believe I need the following commit
to allow Julian's patch to apply cleanly (at all).
bcbde4c ("ipvs: make the service replacement more robust")
On Wed, Oct 09, 2013 at 09:24:27AM +0300, Julian Anastasov wrote:
> 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 <ja@xxxxxx>
> ---
> v2: no changes after v1
>
> 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 1c2e1b9..cd7275f 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 a3df9bd..62786a4 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 eff13c9..ca056a3 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 0b85500..3f21a2f 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);
> }
>
> --
> 1.7.3.4
>
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