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Groups > linux.kernel > #1322479

[PATCH net v2 1/4] net/core: relax BUILD_BUG_ON in netdev_stats_to_stats64

From Jarod Wilson <jarod@redhat.com>
Newsgroups linux.kernel
Subject [PATCH net v2 1/4] net/core: relax BUILD_BUG_ON in netdev_stats_to_stats64
Date 2016-01-30 19:20 +0100
Message-ID <qWIhP-7Qz-9@gated-at.bofh.it> (permalink)
References <qVX9f-5Ao-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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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>
---
Re-re-sending, hopefully getting the patch to the right list this time.

 net/core/dev.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 8cba3d8..575a7df 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7253,25 +7253,30 @@ 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));
 #else
 	size_t i, n = sizeof(*stats64) / sizeof(u64);
 	const unsigned long *src = (const unsigned long *)netdev_stats;
 	u64 *dst = (u64 *)stats64;
 
-	BUILD_BUG_ON(sizeof(*netdev_stats) / sizeof(unsigned long) !=
+	BUILD_BUG_ON(sizeof(*netdev_stats) / sizeof(unsigned long) >
 		     sizeof(*stats64) / sizeof(u64));
 	for (i = 0; i < n; i++)
 		dst[i] = src[i];
 #endif
+	/* zero out counters that only exist in rtnl_link_stats64 */
+	memset((char *)stats64 + sizeof(*netdev_stats), 0,
+	       sizeof(*stats64) - sizeof(*netdev_stats));
 }
 EXPORT_SYMBOL(netdev_stats_to_stats64);
 
-- 
1.8.3.1

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Thread

[PATCH net v2 0/4] net: add and use rx_nohandler stat counter Jarod Wilson <jarod@redhat.com> - 2016-01-28 17:00 +0100
  Re: [PATCH net v2 0/4] net: add and use rx_nohandler stat counter David Miller <davem@davemloft.net> - 2016-01-30 04:40 +0100
    Re: [PATCH net v2 0/4] net: add and use rx_nohandler stat counter Jarod Wilson <jarod@redhat.com> - 2016-01-30 19:20 +0100
  [PATCH net v2 1/4] net/core: relax BUILD_BUG_ON in netdev_stats_to_stats64 Jarod Wilson <jarod@redhat.com> - 2016-01-30 19:20 +0100
    Re: [PATCH net v2 1/4] net/core: relax BUILD_BUG_ON in  netdev_stats_to_stats64 Eric Dumazet <eric.dumazet@gmail.com> - 2016-01-30 19:40 +0100
      Re: [PATCH net v2 1/4] net/core: relax BUILD_BUG_ON in  netdev_stats_to_stats64 Jarod Wilson <jarod@redhat.com> - 2016-01-30 21:40 +0100
        Re: [PATCH net v2 1/4] net/core: relax BUILD_BUG_ON in  netdev_stats_to_stats64 Jarod Wilson <jarod@redhat.com> - 2016-01-30 22:00 +0100
          Re: [PATCH net v2 1/4] net/core: relax BUILD_BUG_ON in  netdev_stats_to_stats64 David Miller <davem@davemloft.net> - 2016-01-31 00:30 +0100
            Re: [PATCH net v2 1/4] net/core: relax BUILD_BUG_ON in  netdev_stats_to_stats64 Jarod Wilson <jarod@redhat.com> - 2016-01-31 19:10 +0100
  [PATCH net v3 4/4] bond: track sum of rx_nohandler for all slaves Jarod Wilson <jarod@redhat.com> - 2016-02-02 01:00 +0100
  [PATCH net v3 0/4] net: add and use rx_nohandler stat counter Jarod Wilson <jarod@redhat.com> - 2016-02-02 01:00 +0100
    [PATCH net v3 1/4] net/core: relax BUILD_BUG_ON in netdev_stats_to_stats64 Jarod Wilson <jarod@redhat.com> - 2016-02-02 01:00 +0100
    [PATCH net v3 2/4] net: add rx_nohandler stat counter Jarod Wilson <jarod@redhat.com> - 2016-02-02 01:00 +0100
      Re: [PATCH net v3 2/4] net: add rx_nohandler stat counter Stephen Hemminger <stephen@networkplumber.org> - 2016-02-07 20:40 +0100
        Re: [PATCH net v3 2/4] net: add rx_nohandler stat counter David Miller <davem@davemloft.net> - 2016-02-07 20:50 +0100
          Re: [PATCH net v3 2/4] net: add rx_nohandler stat counter Eric Dumazet <eric.dumazet@gmail.com> - 2016-02-07 21:20 +0100
            Re: [PATCH net v3 2/4] net: add rx_nohandler stat counter Jarod Wilson <jarod@redhat.com> - 2016-02-08 19:40 +0100
              Re: [PATCH net v3 2/4] net: add rx_nohandler stat counter Stephen Hemminger <stephen@networkplumber.org> - 2016-02-08 20:40 +0100
                Re: [PATCH net v3 2/4] net: add rx_nohandler stat counter Eric Dumazet <eric.dumazet@gmail.com> - 2016-02-09 00:00 +0100
                Re: [PATCH net v3 2/4] net: add rx_nohandler stat counter David Miller <davem@davemloft.net> - 2016-02-09 09:50 +0100
    [PATCH net v3 3/4] team: track sum of rx_nohandler for all slaves Jarod Wilson <jarod@redhat.com> - 2016-02-02 01:00 +0100
    Re: [PATCH net v3 0/4] net: add and use rx_nohandler stat counter David Miller <davem@davemloft.net> - 2016-02-06 09:10 +0100

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