Commit:     76d7cc0345a037e8eea426f8abc710abd22946dd
Parent:     dcb3f974da827c964cb8d419fbb4350cdc08a559
Author:     Roland Dreier <[EMAIL PROTECTED]>
AuthorDate: Tue Oct 9 19:59:17 2007 -0700
Committer:  Roland Dreier <[EMAIL PROTECTED]>
CommitDate: Tue Oct 9 19:59:17 2007 -0700

    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 <[EMAIL PROTECTED]>
    Signed-off-by: Roland Dreier <[EMAIL PROTECTED]>
 drivers/infiniband/hw/mthca/mthca_cmd.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/drivers/infiniband/hw/mthca/mthca_cmd.c 
index acc9589..6966f94 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();
        return err;
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