Patch "net/mlx5e: Fix fixpoint divide exception in mlx5e_am_stats_compare" has been added to the 4.14-stable tree

Patch "net/mlx5e: Fix fixpoint divide exception in mlx5e_am_stats_compare" has been added to the 4.14-stable tree

[gregkh]

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

    net/mlx5e: Fix fixpoint divide exception in mlx5e_am_stats_compare

to the 4.14-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:
     net-mlx5e-fix-fixpoint-divide-exception-in-mlx5e_am_stats_compare.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Sun Jan 28 17:35:08 CET 2018
From: Talat Batheesh <talatb@mellanox.com>
Date: Sun, 21 Jan 2018 05:30:42 +0200
Subject: net/mlx5e: Fix fixpoint divide exception in mlx5e_am_stats_compare

From: Talat Batheesh <talatb@mellanox.com>


[ Upstream commit e58edaa4863583b54409444f11b4f80dff0af1cd ]

Helmut reported a bug about division by zero while
running traffic and doing physical cable pull test.

When the cable unplugged the ppms become zero, so when
dividing the current ppms by the previous ppms in the
next dim iteration there is division by zero.

This patch prevent this division for both ppms and epms.

Fixes: c3164d2fc48f ("net/mlx5e: Added BW check for DIM decision mechanism")
Reported-by: Helmut Grauer <helmut.grauer@de.ibm.com>
Signed-off-by: Talat Batheesh <talatb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_rx_am.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx_am.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx_am.c
@@ -197,9 +197,15 @@ static int mlx5e_am_stats_compare(struct
 		return (curr->bpms > prev->bpms) ? MLX5E_AM_STATS_BETTER :
 						   MLX5E_AM_STATS_WORSE;
 
+	if (!prev->ppms)
+		return curr->ppms ? MLX5E_AM_STATS_BETTER :
+				    MLX5E_AM_STATS_SAME;
+
 	if (IS_SIGNIFICANT_DIFF(curr->ppms, prev->ppms))
 		return (curr->ppms > prev->ppms) ? MLX5E_AM_STATS_BETTER :
 						   MLX5E_AM_STATS_WORSE;
+	if (!prev->epms)
+		return MLX5E_AM_STATS_SAME;
 
 	if (IS_SIGNIFICANT_DIFF(curr->epms, prev->epms))
 		return (curr->epms < prev->epms) ? MLX5E_AM_STATS_BETTER :


Patches currently in stable-queue which might be from talatb@mellanox.com are

queue-4.14/net-mlx5e-fix-fixpoint-divide-exception-in-mlx5e_am_stats_compare.patch