From 2e61c646edfa013203e3428762f8d6a72e10bdea Mon Sep 17 00:00:00 2001 From: Roland Dreier Date: Tue, 9 Oct 2007 19:59:18 -0700 Subject: mlx4_core: Use mmiowb() to avoid firmware commands getting jumbled up Firmware commands are sent to the HCA by writing multiple words to a command register block. Access to this block of registers is serialized with a mutex. However, on large SGI systems writes to the register block may be reordered within the system interconnect and reach the HCA in a different order than they were issued (even with the mutex). Fix this by adding an mmiowb() before dropping the mutex. This bug was observed with real workloads with the similar FW command code in the mthca driver, and adding the mmiowb() as in commit 66547550 ("IB/mthca: Use mmiowb() to avoid firmware commands getting jumbled up") was confirmed to fix the problems, so we should add the same fix to mlx4. Signed-off-by: Roland Dreier --- drivers/net/mlx4/cmd.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'drivers/net/mlx4/cmd.c') diff --git a/drivers/net/mlx4/cmd.c b/drivers/net/mlx4/cmd.c index b540820e9c25..db49051b97b1 100644 --- a/drivers/net/mlx4/cmd.c +++ b/drivers/net/mlx4/cmd.c @@ -184,6 +184,13 @@ static int mlx4_cmd_post(struct mlx4_dev *dev, u64 in_param, u64 out_param, (event ? (1 << HCR_E_BIT) : 0) | (op_modifier << HCR_OPMOD_SHIFT) | op), hcr + 6); + + /* + * Make sure that our HCR writes don't get mixed in with + * writes from another CPU starting a FW command. + */ + mmiowb(); + cmd->toggle = cmd->toggle ^ 1; ret = 0; -- cgit v1.2.3