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Commit 9256645a authored by Jarod Wilson's avatar Jarod Wilson Committed by David S. Miller
Browse files

net/core: relax BUILD_BUG_ON in netdev_stats_to_stats64 



The netdev_stats_to_stats64 function copies the deprecated
net_device_stats format stats into rtnl_link_stats64 for legacy support
purposes, but with the BUILD_BUG_ON as it was, it wasn't possible to
extend rtnl_link_stats64 without also extending net_device_stats. Relax
the BUILD_BUG_ON to only require that rtnl_link_stats64 is larger, and
zero out all the stat counters that aren't present in net_device_stats.

CC: Eric Dumazet <edumazet@google.com>
CC: netdev@vger.kernel.org
Signed-off-by: default avatarJarod Wilson <jarod@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 81729810

net/core/dev.c

+13 −6
Original line number Diff line number Diff line
@@ -7253,24 +7253,31 @@ void netdev_run_todo(void) 
	}

}



/* Convert net_device_stats to rtnl_link_stats64.  They have the same

 * fields in the same order, with only the type differing.

/* Convert net_device_stats to rtnl_link_stats64. rtnl_link_stats64 has

 * all the same fields in the same order as net_device_stats, with only

 * the type differing, but rtnl_link_stats64 may have additional fields

 * at the end for newer counters.

 */

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));

	BUILD_BUG_ON(sizeof(*stats64) < sizeof(*netdev_stats));

	memcpy(stats64, netdev_stats, sizeof(*stats64));

	/* 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(*stats64) / sizeof(u64);

	size_t i, n = sizeof(*netdev_stats) / sizeof(unsigned long);

	const unsigned long *src = (const unsigned long *)netdev_stats;

	u64 *dst = (u64 *)stats64;



	BUILD_BUG_ON(sizeof(*netdev_stats) / sizeof(unsigned long) !=

		     sizeof(*stats64) / sizeof(u64));

	BUILD_BUG_ON(n > sizeof(*stats64) / sizeof(u64));

	for (i = 0; i < n; i++)

		dst[i] = 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);