diff mbox series

[net] net/mlx5e: Fix fixpoint divide exception in mlx5e_am_stats_compare

Message ID 20180119201031.20401-1-saeedm@mellanox.com
State Superseded, archived
Delegated to: David Miller
Headers show
Series [net] net/mlx5e: Fix fixpoint divide exception in mlx5e_am_stats_compare | expand

Commit Message

Saeed Mahameed Jan. 19, 2018, 8:10 p.m. UTC 
From: Talat Batheesh <talatb@mellanox.com>

Helmut reported a bug about devision 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 devision 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>
---
This patch is the equivalent of:
("net/dim: Fix fixpoint divide exception in net_dim_stats_compare")
which was already submitted to net-next. Since mlx5 irq moderation code
got moved in net-next, this patch should only go to net and skip net-next.

for -stable: 4.12.y and later.

 drivers/net/ethernet/mellanox/mlx5/core/en_rx_am.c | 6 ++++++
 1 file changed, 6 insertions(+)

Comments

Sergei Shtylyov Jan. 20, 2018, 8:10 a.m. UTC | #1 
Hello!

On 1/19/2018 11:10 PM, Saeed Mahameed wrote:

> From: Talat Batheesh <talatb@mellanox.com>
> 
> Helmut reported a bug about devision by zero while

    Division.

> 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

    You got it right the on the 2nd time. :-)

> next dim iteration there is devision 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>
[...]

MBR, Sergei
Saeed Mahameed Jan. 21, 2018, 3:32 a.m. UTC | #2 
On 01/20/2018 12:10 AM, Sergei Shtylyov wrote:
> Hello!
> 
> On 1/19/2018 11:10 PM, Saeed Mahameed wrote:
> 
>> From: Talat Batheesh <talatb@mellanox.com>
>>
>> Helmut reported a bug about devision by zero while
> 
>    Division.
> 
>> 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
> 
>    You got it right the on the 2nd time. :-)
> 

BTW, you missed one ;-)
Fixed both in V2.

Thanks !
diff mbox series

Patch

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx_am.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx_am.c
index e401d9d245f3..b69a705fd787 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx_am.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx_am.c
@@ -201,9 +201,15 @@  static int mlx5e_am_stats_compare(struct mlx5e_rx_am_stats *curr,
 		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 :