From: Arthur Jones Date: Thu, 18 Oct 2007 01:18:29 +0000 (-0700) Subject: IB/ipath: Better comment for rmb() in ipath_intr() X-Git-Tag: v2.6.25-rc1~1234^2~61 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2f01a7001131bbf3ce1e39252bf72aea2da034df;p=linux-2.6 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 Signed-off-by: Roland Dreier --- diff --git a/drivers/infiniband/hw/ipath/ipath_intr.c b/drivers/infiniband/hw/ipath/ipath_intr.c index eac2e9c552..4795cb895f 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)