tree 49936369d48985749a4beda048b6f3b5e5f31c2e
parent dcb3f974da827c964cb8d419fbb4350cdc08a559
author Roland Dreier <rolandd@cisco.com> 1191985157 -0700
committer Roland Dreier <rolandd@cisco.com> 1191985157 -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 <akepner@sgi.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>