From 181d4447905d551cc664f1e7e796b482c1eec992 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 7 Feb 2022 11:07:06 -0800 Subject: [PATCH] can: gw: use call_rcu() instead of costly synchronize_rcu() Commit fb8696ab14ad ("can: gw: synchronize rcu operations before removing gw job entry") added three synchronize_rcu() calls to make sure one rcu grace period was observed before freeing a "struct cgw_job" (which are tiny objects). This should be converted to call_rcu() to avoid adding delays in device / network dismantles. Use the rcu_head that was already in struct cgw_job, not yet used. Link: https://lore.kernel.org/all/20220207190706.1499190-1-eric.dumazet@gmail.com Signed-off-by: Eric Dumazet Cc: Oliver Hartkopp Tested-by: Oliver Hartkopp Signed-off-by: Marc Kleine-Budde --- net/can/gw.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/net/can/gw.c b/net/can/gw.c index 24221352e059..1ea4cc527db3 100644 --- a/net/can/gw.c +++ b/net/can/gw.c @@ -577,6 +577,13 @@ static inline void cgw_unregister_filter(struct net *net, struct cgw_job *gwj) gwj->ccgw.filter.can_mask, can_can_gw_rcv, gwj); } +static void cgw_job_free_rcu(struct rcu_head *rcu_head) +{ + struct cgw_job *gwj = container_of(rcu_head, struct cgw_job, rcu); + + kmem_cache_free(cgw_cache, gwj); +} + static int cgw_notifier(struct notifier_block *nb, unsigned long msg, void *ptr) { @@ -596,8 +603,7 @@ static int cgw_notifier(struct notifier_block *nb, if (gwj->src.dev == dev || gwj->dst.dev == dev) { hlist_del(&gwj->list); cgw_unregister_filter(net, gwj); - synchronize_rcu(); - kmem_cache_free(cgw_cache, gwj); + call_rcu(&gwj->rcu, cgw_job_free_rcu); } } } @@ -1155,8 +1161,7 @@ static void cgw_remove_all_jobs(struct net *net) hlist_for_each_entry_safe(gwj, nx, &net->can.cgw_list, list) { hlist_del(&gwj->list); cgw_unregister_filter(net, gwj); - synchronize_rcu(); - kmem_cache_free(cgw_cache, gwj); + call_rcu(&gwj->rcu, cgw_job_free_rcu); } } @@ -1224,8 +1229,7 @@ static int cgw_remove_job(struct sk_buff *skb, struct nlmsghdr *nlh, hlist_del(&gwj->list); cgw_unregister_filter(net, gwj); - synchronize_rcu(); - kmem_cache_free(cgw_cache, gwj); + call_rcu(&gwj->rcu, cgw_job_free_rcu); err = 0; break; }