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net/core: relax BUILD_BUG_ON in netdev_stats_to_stats64

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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: Jarod Wilson <jarod@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jarod Wilson 2016-02-01 18:51:04 -05:00 committed by David S. Miller
parent 817298102b
commit 9256645af0
1 changed files with 13 additions and 6 deletions
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19
net/core/dev.c
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@ -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);