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Commit 142c6594 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

bonding: refine bond_fold_stats() wrap detection 



Some device drivers reset their stats at down/up events, possibly
fooling bonding stats, since they operate with relative deltas.

It is nearly not possible to fix drivers, since some of them compute the
tx/rx counters based on per rx/tx queue stats, and the queues can be
reconfigured (ethtool -L) between the down/up sequence.

Lets avoid accumulating 'negative' values that render bonding stats
useless.

It is better to lose small deltas, assuming the bonding stats are
fetched at a reasonable frequency.

Fixes: 5f0c5f73 ("bonding: make global bonding stats more reliable")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ed8bfd5c

drivers/net/bonding/bond_main.c

+8 −3
Original line number Diff line number Diff line
@@ -3332,12 +3332,17 @@ static void bond_fold_stats(struct rtnl_link_stats64 *_res, 
	for (i = 0; i < sizeof(*_res) / sizeof(u64); i++) {

		u64 nv = new[i];

		u64 ov = old[i];

		s64 delta = nv - ov;



		/* detects if this particular field is 32bit only */

		if (((nv | ov) >> 32) == 0)

			res[i] += (u32)nv - (u32)ov;

		else

			res[i] += nv - ov;

			delta = (s64)(s32)((u32)nv - (u32)ov);



		/* filter anomalies, some drivers reset their stats

		 * at down/up events.

		 */

		if (delta > 0)

			res[i] += delta;

	}

}