net: Fix a data-race around netdev_unregister_timeout_secs.

[ Upstream commit 05e49cfc89e4f325eebbc62d24dd122e55f94c23 ]

While reading netdev_unregister_timeout_secs, it can be changed
concurrently.  Thus, we need to add READ_ONCE() to its reader.

Fixes: 5aa3afe107d9 ("net: make unregister netdev warning timeout configurable")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/core/dev.c b/net/core/dev.c
index 19baeaf65a6466c5d88216b6a9a4b91a3222dd63..a77a979a4bf752f92edbb9eba5d99b1a325b203f 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -10265,7 +10265,7 @@ static struct net_device *netdev_wait_allrefs_any(struct list_head *list)
                                return dev;
 
                if (time_after(jiffies, warning_time +
-                              netdev_unregister_timeout_secs * HZ)) {
+                              READ_ONCE(netdev_unregister_timeout_secs) * HZ)) {
                        list_for_each_entry(dev, list, todo_list) {
                                pr_emerg("unregister_netdevice: waiting for %s to become free. Usage count = %d\n",
                                         dev->name, netdev_refcnt_read(dev));