From 9256645af09807bc52fa8b2e66ecd28ab25318c4 Mon Sep 17 00:00:00 2001 From: Jarod Wilson Date: Mon, 1 Feb 2016 18:51:04 -0500 Subject: [PATCH] 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 CC: netdev@vger.kernel.org Signed-off-by: Jarod Wilson Signed-off-by: David S. Miller --- net/core/dev.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 8cba3d852f25..65863e512227 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -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); -- 2.20.1