From 142c6594acbcc32391af9c15f8cd65c6c177698f Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 29 Mar 2017 10:45:44 -0700 Subject: [PATCH] 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: 5f0c5f73e5ef ("bonding: make global bonding stats more reliable") Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- 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 6cea964ab70a..27359dab78a1 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -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; } }