Merge branch 'net-atomic-dev-stats'

Eric Dumazet says:

====================
net: add atomic dev->stats infra

Long standing KCSAN issues are caused by data-race around
some dev->stats changes.

Most performance critical paths already use per-cpu
variables, or per-queue ones.

It is reasonable (and more correct) to use atomic operations
for the slow paths.

First patch adds the infrastructure, then three patches address
the most common paths that syzbot is playing with.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 11 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index fb943dad9651..d0fb4af9a126 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -10369,24 +10369,16 @@ void netdev_run_todo(void)
 void netdev_stats_to_stats64(struct rtnl_link_stats64 *stats64,
 			     const struct net_device_stats *netdev_stats)
 {
-#if BITS_PER_LONG == 64
-	BUILD_BUG_ON(sizeof(*stats64) < sizeof(*netdev_stats));
-	memcpy(stats64, netdev_stats, sizeof(*netdev_stats));
-	/* zero out counters that only exist in rtnl_link_stats64 */
-	memset((char *)stats64 + sizeof(*netdev_stats), 0,
-	       sizeof(*stats64) - sizeof(*netdev_stats));
-#else
-	size_t i, n = sizeof(*netdev_stats) / sizeof(unsigned long);
-	const unsigned long *src = (const unsigned long *)netdev_stats;
+	size_t i, n = sizeof(*netdev_stats) / sizeof(atomic_long_t);
+	const atomic_long_t *src = (atomic_long_t *)netdev_stats;
 	u64 *dst = (u64 *)stats64;
 
 	BUILD_BUG_ON(n > sizeof(*stats64) / sizeof(u64));
 	for (i = 0; i < n; i++)
-		dst[i] = src[i];
+		dst[i] = atomic_long_read(&src[i]);
 	/* zero out counters that only exist in rtnl_link_stats64 */
 	memset((char *)stats64 + n * sizeof(u64), 0,
 	       sizeof(*stats64) - n * sizeof(u64));
-#endif
 }
 EXPORT_SYMBOL(netdev_stats_to_stats64);