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can: gw: use call_rcu() instead of costly synchronize_rcu()

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Commit fb8696ab14 ("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 <edumazet@google.com>
Cc: Oliver Hartkopp <socketcan@hartkopp.net>
Tested-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Eric Dumazet 2022-02-07 11:07:06 -08:00 committed by Marc Kleine-Budde
parent 58212e03e5
commit 181d444790
1 changed files with 10 additions and 6 deletions
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16
net/can/gw.c
View file

@ -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;
}