From 76d7cc0345a037e8eea426f8abc710abd22946dd Mon Sep 17 00:00:00 2001 From: Roland Dreier Date: Tue, 9 Oct 2007 19:59:17 -0700 Subject: [PATCH] IB/mthca: 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, problems were seen with multiple CPUs issuing FW commands at the same time, because the 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. Tested-by: Arthur Kepner Signed-off-by: Roland Dreier --- drivers/infiniband/hw/mthca/mthca_cmd.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/infiniband/hw/mthca/mthca_cmd.c b/drivers/infiniband/hw/mthca/mthca_cmd.c index acc9589271..6966f943f4 100644 --- a/drivers/infiniband/hw/mthca/mthca_cmd.c +++ b/drivers/infiniband/hw/mthca/mthca_cmd.c @@ -290,6 +290,12 @@ static int mthca_cmd_post(struct mthca_dev *dev, err = mthca_cmd_post_hcr(dev, in_param, out_param, in_modifier, op_modifier, op, token, event); + /* + * Make sure that our HCR writes don't get mixed in with + * writes from another CPU starting a FW command. + */ + mmiowb(); + mutex_unlock(&dev->cmd.hcr_mutex); return err; } -- 2.39.5