| From foo@baz Sun Mar 18 16:55:33 CET 2018 |
| From: Eric Dumazet <edumazet@google.com> |
| Date: Wed, 29 Mar 2017 10:45:44 -0700 |
| Subject: bonding: refine bond_fold_stats() wrap detection |
| |
| 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> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| drivers/net/bonding/bond_main.c | 11 ++++++++--- |
| 1 file changed, 8 insertions(+), 3 deletions(-) |
| |
| --- 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_ |
| 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; |
| } |
| } |
| |