Patch "net/mlx4: Copy/set only sizeof struct mlx4_eqe bytes" has been added to the 3.14-stable tree

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

net/mlx4: Copy/set only sizeof struct mlx4_eqe bytes

to the 3.14-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-mlx4-copy-set-only-sizeof-struct-mlx4_eqe-bytes.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Carol L Soto <[email protected]>
Date: Tue, 27 Oct 2015 17:36:20 +0200
Subject: net/mlx4: Copy/set only sizeof struct mlx4_eqe bytes

From: Carol L Soto <[email protected]>

[ Upstream commit c02b05011fadf8e409e41910217ca689f2fc9d91 ]

When doing memcpy/memset of EQEs, we should use sizeof struct mlx4_eqe as the base size and not caps.eqe_size which could be bigger.

If caps.eqe_size is bigger than the struct mlx4_eqe then we corrupt data in the master context.

When using a 64 byte stride, the memcpy copied over 63 bytes to the slave_eq structure. This resulted in copying over the entire eqe of interest, including its ownership bit -- and also 31 bytes of garbage into the next WQE in the slave EQ -- which did NOT include the ownership bit (and therefore had no impact).

However, once the stride is increased to 128, we are overwriting the ownership bits of *three* eqes in the slave_eq struct. This results in an incorrect ownership bit for those eqes, which causes the eq to seem to be full. The issue therefore surfaced only once 128-byte EQEs started being used in SRIOV and (overarchitectures that have 128/256 byte cache-lines such as PPC) - e.g after commit 77507aa249ae "net/mlx4_core: Enable CQE/EQE stride support".

---
 drivers/net/ethernet/mellanox/mlx4/cmd.c |    2 +-
 drivers/net/ethernet/mellanox/mlx4/eq.c  |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

@@ -1987,7 +1987,7 @@ int mlx4_multi_func_init(struct mlx4_dev
 			spin_lock_init(&s_state->lock);
 		}
 
-		memset(&priv->mfunc.master.cmd_eqe, 0, dev->caps.eqe_size);
+		memset(&priv->mfunc.master.cmd_eqe, 0, sizeof(struct mlx4_eqe));
 		priv->mfunc.master.cmd_eqe.type = MLX4_EVENT_TYPE_CMD;
 		INIT_WORK(&priv->mfunc.master.comm_work,
 			  mlx4_master_comm_channel);

@@ -183,7 +183,7 @@ static void slave_event(struct mlx4_dev
 		return;
 	}
 
-	memcpy(s_eqe, eqe, dev->caps.eqe_size - 1);
+	memcpy(s_eqe, eqe, sizeof(struct mlx4_eqe) - 1);
 	s_eqe->slave_id = slave;
 	/* ensure all information is written before setting the ownersip bit */
 	wmb();

Patches currently in stable-queue which might be from [email protected] are

queue-3.14/net-mlx4-copy-set-only-sizeof-struct-mlx4_eqe-bytes.patch