[ofa-general] [PATCH 5/6] IB/ipath - better comment for rmb() in ipath_intr()

[Arthur Jones]

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 at qlogic.com>
---

 drivers/infiniband/hw/ipath/ipath_intr.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

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 @@ static void handle_urcv(struct ipath_devdata *dd, u32 istat)
 	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)