net/dst: dst_dev_event() called after other notifiers

[ Upstream commit 332dd96f7ac15e937088fe11f15cfe0210e8edd1 ]

Followup of commit ef885afbf8a37689 (net: use rcu_barrier() in
rollback_registered_many)

dst_dev_event() scans a garbage dst list that might be feeded by various
network notifiers at device dismantle time.

Its important to call dst_dev_event() after other notifiers, or we might
enter the infamous msleep(250) in netdev_wait_allrefs(), and wait one
second before calling again call_netdevice_notifiers(NETDEV_UNREGISTER,
dev) to properly remove last device references.

Use priority -10 to let dst_dev_notifier be called after other network
notifiers (they have the default 0 priority)

Reported-by: Ben Greear <greearb@candelatech.com>
Reported-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reported-by: Octavian Purdila <opurdila@ixiacom.com>
Reported-by: Benjamin LaHaise <bcrl@kvack.org>
Tested-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

diff --git a/net/core/dst.c b/net/core/dst.c
index 9920722cc82b84490cc75d2010976d5652ae4f4b..1ebf5e052f618af2a2df887b9935c1b262330567 100644 (file)
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -343,6 +343,7 @@ static int dst_dev_event(struct notifier_block *this, unsigned long event,
 
 static struct notifier_block dst_dev_notifier = {
        .notifier_call  = dst_dev_event,
+       .priority = -10, /* must be called after other network notifiers */
 };
 
 void __init dst_init(void)