| From | Sasha Levin <> | Subject | [PATCH AUTOSEL for 4.9 087/219] bonding: refine bond_fold_stats() wrap detection | Date | Sat, 3 Mar 2018 22:28:46 +0000 |
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From: Eric Dumazet <edumazet@google.com>
[ Upstream commit 142c6594acbcc32391af9c15f8cd65c6c177698f ]
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: 5f0c5f73e5ef ("bonding: make global bonding stats more reliable") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> --- drivers/net/bonding/bond_main.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index 6b4b43319ffa..c3f3096b24ae 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -3331,12 +3331,17 @@ 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; } } -- 2.14.1
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