Patch "bonding: refine bond_fold_stats() wrap detection" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

bonding: refine bond_fold_stats() wrap detection

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
bonding-refine-bond_fold_stats-wrap-detection.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Eric Dumazet <[email protected]>
Date: Wed, 29 Mar 2017 10:45:44 -0700
Subject: bonding: refine bond_fold_stats() wrap detection

From: Eric Dumazet <[email protected]>

[ 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.

---
 drivers/net/bonding/bond_main.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

@@ -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;
 	}
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/selinux-check-for-address-length-in-selinux_socket_bind.patch queue-4.9/bonding-refine-bond_fold_stats-wrap-detection.patch