From: Eli Cohen <eli@mellanox.com>
Date: Sun, 2 Sep 2018 12:01:53 +0300
Subject: net/mlx5: Fix read from coherent memory
Patch-mainline: v4.19-rc6
Git-commit: 250ae0d46d857ed61f3e0abf584901e46bd2c638
References: bsc#1103990 FATE#326006

Use accessor function READ_ONCE to read from coherent memory modified
by the device and read by the driver. This becomes most important in
preemptive kernels where cond_resched implementation does not have the
side effect which guaranteed the updated value.

Fixes: 269d26f47f6f ("net/mlx5: Reduce command polling interval")
Change-Id: Ie6deeb565ffaf76777b07448c7fbcce3510bbb8a
Signed-off-by: Eli Cohen <eli@mellanox.com>
Reported-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/mellanox/mlx5/core/cmd.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/cmd.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/cmd.c
@@ -206,7 +206,7 @@ static void poll_timeout(struct mlx5_cmd
 	u8 own;
 
 	do {
-		own = ent->lay->status_own;
+		own = READ_ONCE(ent->lay->status_own);
 		if (!(own & CMD_OWNER_HW)) {
 			ent->ret = 0;
 			return;