Commit 181d4447 authored by Eric Dumazet's avatar Eric Dumazet Committed by Marc Kleine-Budde
Browse files

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

Commit fb8696ab ("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: default avatarEric Dumazet <edumazet@google.com>
Cc: Oliver Hartkopp <socketcan@hartkopp.net>
Tested-by: default avatarOliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent 58212e03

net/can/gw.c

+10 −6
Original line number Diff line number Diff line
@@ -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;

	}