Hi,
Martin KaFai Lau wrote:
> The patch checks neigh->nud_state before acquiring the writer lock.
> Note that rt6_probe() is only used in CONFIG_IPV6_ROUTER_PREF.
You have to take "some" lock when accessing neigh->nud_state
theoretically.
>
> I also take this chance to re-arrange the code.
No, please do not mix multiple changes.
>
> 40 udpflood processes and a /64 gateway route are used.
> The gateway has NUD_PERMANENT. Each of them is run for 30s.
> At the end, the total number of finished sendto():
>
> Before After
> 55M 95M
>
> Signed-off-by: Martin KaFai Lau <ka...@fb.com>
> Cc: Hannes Frederic Sowa <han...@stressinduktion.org>
> ---
> net/ipv6/route.c | 41 ++++++++++++++++++++---------------------
> 1 file changed, 20 insertions(+), 21 deletions(-)
>
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index 6090969..a6c6b5a 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -544,6 +544,7 @@ static void rt6_probe_deferred(struct work_struct *w)
>
> static void rt6_probe(struct rt6_info *rt)
> {
> + struct __rt6_probe_work *work;
> struct neighbour *neigh;
> /*
> * Okay, this does not seem to be appropriate
> @@ -558,34 +559,32 @@ static void rt6_probe(struct rt6_info *rt)
> rcu_read_lock_bh();
> neigh = __ipv6_neigh_lookup_noref(rt->dst.dev, &rt->rt6i_gateway);
> if (neigh) {
> - write_lock(&neigh->lock);
> if (neigh->nud_state & NUD_VALID)
> goto out;
> - }
> -
> - if (!neigh ||
> - time_after(jiffies, neigh->updated +
> rt->rt6i_idev->cnf.rtr_probe_interval)) {
> - struct __rt6_probe_work *work;
>
> + work = NULL;
> + write_lock(&neigh->lock);
> + if (!(neigh->nud_state & NUD_VALID) &&
> + time_after(jiffies, neigh->updated +
> rt->rt6i_idev->cnf.rtr_probe_interval)) {
> + work = kmalloc(sizeof(*work), GFP_ATOMIC);
> + if (work) {
> + __neigh_set_probe_once(neigh);
> + }
> + }
> + write_unlock(&neigh->lock);
> + } else {
> work = kmalloc(sizeof(*work), GFP_ATOMIC);
> + }
>
> - if (neigh && work)
> - __neigh_set_probe_once(neigh);
> -
> - if (neigh)
> - write_unlock(&neigh->lock);
> + if (work) {
> + INIT_WORK(&work->work, rt6_probe_deferred);
> + work->target = rt->rt6i_gateway;
> + dev_hold(rt->dst.dev);
> + work->dev = rt->dst.dev;
> + schedule_work(&work->work);
> + }
>
> - if (work) {
> - INIT_WORK(&work->work, rt6_probe_deferred);
> - work->target = rt->rt6i_gateway;
> - dev_hold(rt->dst.dev);
> - work->dev = rt->dst.dev;
> - schedule_work(&work->work);
> - }
> - } else {
> out:
> - write_unlock(&neigh->lock);
> - }
> rcu_read_unlock_bh();
> }
> #else
>
--
Hideaki Yoshifuji <hideaki.yoshif...@miraclelinux.com>
Technical Division, MIRACLE LINUX CORPORATION
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