IB/ipath: Add barrier before updating WC head in shared memory
Add a barrier to make sure the CPU doesn't reorder writes to memory,
since user programs can be polling on the head index update and the
entry should be written before that.
Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/ipath/ipath_srq.c b/drivers/infiniband/hw/ipath/ipath_srq.c
index 14cbbd6..40c36ec 100644
--- a/drivers/infiniband/hw/ipath/ipath_srq.c
+++ b/drivers/infiniband/hw/ipath/ipath_srq.c
@@ -80,6 +80,8 @@
wqe->num_sge = wr->num_sge;
for (i = 0; i < wr->num_sge; i++)
wqe->sg_list[i] = wr->sg_list[i];
+ /* Make sure queue entry is written before the head index. */
+ smp_wmb();
wq->head = next;
spin_unlock_irqrestore(&srq->rq.lock, flags);
}