On weakly-ordered systems, the reading of an event's content must occur
after reading the event's validity.
Signed-off-by: Matt Evans <m...@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
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
