From: Amir Vadai <[email protected]>

[ Upstream commit a229e488ac3f904d06c20d8d3f47831db3c7a15a ]

Commit 37706996 "mlx4_en: fix allocation of CPU affinity reverse-map" fixed
a bug when mlx4_dev->caps.comp_pool is larger from the device rx rings, but
introduced a regression.

When the mlx4_core is activating its "legacy mode" (e.g when running in SRIOV
mode) w.r.t to EQs/IRQs usage, comp_pool becomes zero and we're crashing on
divide by zero alloc_cpu_rmap.

Fix that by enabling RFS only when running in non-legacy mode.

Reported-by: Yan Burman <[email protected]>
Cc: Kleber Sacilotto de Souza <[email protected]>
Signed-off-by: Amir Vadai <[email protected]>
Signed-off-by: Or Gerlitz <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
---
 drivers/net/ethernet/mellanox/mlx4/en_netdev.c |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c 
b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
index 17a14c1..bf3f4bc 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
@@ -1434,9 +1434,11 @@ int mlx4_en_alloc_resources(struct mlx4_en_priv *priv)
        }
 
 #ifdef CONFIG_RFS_ACCEL
-       priv->dev->rx_cpu_rmap = 
alloc_irq_cpu_rmap(priv->mdev->dev->caps.comp_pool);
-       if (!priv->dev->rx_cpu_rmap)
-               goto err;
+       if (priv->mdev->dev->caps.comp_pool) {
+               priv->dev->rx_cpu_rmap = 
alloc_irq_cpu_rmap(priv->mdev->dev->caps.comp_pool);
+               if (!priv->dev->rx_cpu_rmap)
+                       goto err;
+       }
 #endif
 
        return 0;
-- 
1.7.1

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