IB/ipath: Better comment for rmb() in ipath_intr()
An internal code review found the comment here lacking -- update it with
more specifics of how and why the rmb() is there.
Signed-off-by: Arthur Jones <arthur.jones@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/ipath/ipath_intr.c b/drivers/infiniband/hw/ipath/ipath_intr.c
index eac2e9c..4795cb8 100644
--- a/drivers/infiniband/hw/ipath/ipath_intr.c
+++ b/drivers/infiniband/hw/ipath/ipath_intr.c
@@ -954,7 +954,15 @@
int i;
int rcvdint = 0;
- /* test_bit below needs this... */
+ /*
+ * test_and_clear_bit(IPATH_PORT_WAITING_RCV) and
+ * test_and_clear_bit(IPATH_PORT_WAITING_URG) below
+ * would both like timely updates of the bits so that
+ * we don't pass them by unnecessarily. the rmb()
+ * here ensures that we see them promptly -- the
+ * corresponding wmb()'s are in ipath_poll_urgent()
+ * and ipath_poll_next()...
+ */
rmb();
portr = ((istat >> INFINIPATH_I_RCVAVAIL_SHIFT) &
dd->ipath_i_rcvavail_mask)