[3.11.y.z extended stable] Patch "mlx4_en: don't use napi_synchronize inside mlx4_en_netpoll" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    mlx4_en: don't use napi_synchronize inside mlx4_en_netpoll

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 86cf70f1b819d85f38875045e93cde3e6276c36b Mon Sep 17 00:00:00 2001
From: Chris Mason <clm at fb.com>
Date: Tue, 15 Apr 2014 18:09:24 -0400
Subject: mlx4_en: don't use napi_synchronize inside mlx4_en_netpoll

commit c98235cb8584a72e95786e17d695a8e5fafcd766 upstream.

The mlx4 driver is triggering schedules while atomic inside
mlx4_en_netpoll:

	spin_lock_irqsave(&cq->lock, flags);
	napi_synchronize(&cq->napi);
		^^^^^ msleep here
	mlx4_en_process_rx_cq(dev, cq, 0);
	spin_unlock_irqrestore(&cq->lock, flags);

This was part of a patch by Alexander Guller from Mellanox in 2011,
but it still isn't upstream.

Signed-off-by: Chris Mason <clm at fb.com>
Acked-By: Amir Vadai <amirv at mellanox.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
[ luis: backported to 3.11: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/ethernet/mellanox/mlx4/en_cq.c     | 1 -
 drivers/net/ethernet/mellanox/mlx4/en_netdev.c | 6 +-----
 drivers/net/ethernet/mellanox/mlx4/mlx4_en.h   | 1 -
 3 files changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_cq.c b/drivers/net/ethernet/mellanox/mlx4/en_cq.c
index 3e2d504..d9303d8 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_cq.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_cq.c
@@ -55,7 +55,6 @@ int mlx4_en_create_cq(struct mlx4_en_priv *priv,

 	cq->ring = ring;
 	cq->is_tx = mode;
-	spin_lock_init(&cq->lock);

 	err = mlx4_alloc_hwq_res(mdev->dev, &cq->wqres,
 				cq->buf_size, 2 * PAGE_SIZE);
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
index fa37b7a..35d3821 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
@@ -1219,15 +1219,11 @@ static void mlx4_en_netpoll(struct net_device *dev)
 {
 	struct mlx4_en_priv *priv = netdev_priv(dev);
 	struct mlx4_en_cq *cq;
-	unsigned long flags;
 	int i;

 	for (i = 0; i < priv->rx_ring_num; i++) {
 		cq = &priv->rx_cq[i];
-		spin_lock_irqsave(&cq->lock, flags);
-		napi_synchronize(&cq->napi);
-		mlx4_en_process_rx_cq(dev, cq, 0);
-		spin_unlock_irqrestore(&cq->lock, flags);
+		napi_schedule(&cq->napi);
 	}
 }
 #endif
diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
index bf06e36..a47455f 100644
--- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
+++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
@@ -306,7 +306,6 @@ struct mlx4_en_cq {
 	struct mlx4_cq          mcq;
 	struct mlx4_hwq_resources wqres;
 	int                     ring;
-	spinlock_t              lock;
 	struct net_device      *dev;
 	struct napi_struct	napi;
 	int size;
--
1.9.1