From 181d4447905d551cc664f1e7e796b482c1eec992 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
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 <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>
---
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 24221352e059b..1ea4cc527db3a 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;
}
--
2.30.2