5.10-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit 181d4447905d551cc664f1e7e796b482c1eec992 ]
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 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 Stable-dep-of: 511e64e13d8c ("can: gw: fix RCU/BH usage in cgw_create_job()") Signed-off-by: Sasha Levin sashal@kernel.org --- 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 cbb46d3aa9634..59ce23996c6e0 100644 --- a/net/can/gw.c +++ b/net/can/gw.c @@ -515,6 +515,13 @@ 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) { @@ -534,8 +541,7 @@ 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); } } } @@ -1093,8 +1099,7 @@ 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); } }
@@ -1162,8 +1167,7 @@ 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; }