USB: fix race between root-hub resume and wakeup requests

commit bf3d7d40e42a85ca73a34e1385ff34f092a384eb upstream.

The USB core keeps track of pending resume requests for root hubs, in
order to resolve races between wakeup requests and suspends.  However
the code that does this is subject to another race (between wakeup
requests and resumes) because the WAKEUP_PENDING flag is cleared
before the resume occurs, leaving a window in which another wakeup
request might arrive.

This patch (as1447) fixes the problem by clearing the WAKEUP_PENDING
flag after the resume instead of before it.

This fixes Bugzilla #24952.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Paul Bender <pebender@san.rr.com>
Tested-by: warpme <warpme@o2.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 5cca00a6d09d61dfe31859b866463b80091451a3..b5c965c031f92d0cac8b51b56541620e55a4e9c8 100644 (file)
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1945,7 +1945,6 @@ int hcd_bus_resume(struct usb_device *rhdev, pm_message_t msg)
 
        dev_dbg(&rhdev->dev, "usb %s%s\n",
                        (msg.event & PM_EVENT_AUTO ? "auto-" : ""), "resume");
-       clear_bit(HCD_FLAG_WAKEUP_PENDING, &hcd->flags);
        if (!hcd->driver->bus_resume)
                return -ENOENT;
        if (hcd->state == HC_STATE_RUNNING)
@@ -1953,6 +1952,7 @@ int hcd_bus_resume(struct usb_device *rhdev, pm_message_t msg)
 
        hcd->state = HC_STATE_RESUMING;
        status = hcd->driver->bus_resume(hcd);
+       clear_bit(HCD_FLAG_WAKEUP_PENDING, &hcd->flags);
        if (status == 0) {
                /* TRSMRCY = 10 msec */
                msleep(10);