* [PATCH v3 2/4] xhci: Add rmb() between reading event validity & event data access.
@ 2011-03-29 2:40 Matt Evans
0 siblings, 0 replies; only message in thread
From: Matt Evans @ 2011-03-29 2:40 UTC (permalink / raw)
To: Sarah Sharp; +Cc: linuxppc-dev, linux-usb
On weakly-ordered systems, the reading of an event's content must occur
after reading the event's validity.
Signed-off-by: Matt Evans <matt@ozlabs.org>
---
drivers/usb/host/xhci-ring.c | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 1361032..86c8198 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2150,6 +2150,11 @@ static void xhci_handle_event(struct xhci_hcd *xhci)
}
xhci_dbg(xhci, "%s - OS owns TRB\n", __func__);
+ /*
+ * Barrier between reading the TRB_CYCLE (valid) flag above and any
+ * speculative reads of the event's flags/data below.
+ */
+ rmb();
/* FIXME: Handle more event types. */
switch ((le32_to_cpu(event->event_cmd.flags) & TRB_TYPE_BITMASK)) {
case TRB_TYPE(TRB_COMPLETION):
--
1.7.0.4
^ permalink raw reply related [flat|nested] only message in thread
only message in thread, other threads:[~2011-03-29 2:40 UTC | newest]
Thread overview: (only message) (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-03-29 2:40 [PATCH v3 2/4] xhci: Add rmb() between reading event validity & event data access Matt Evans
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.