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authorAlan Stern <stern@rowland.harvard.edu>2007-03-13 15:10:52 (GMT)
committerGreg Kroah-Hartman <gregkh@suse.de>2007-04-27 20:28:34 (GMT)
commit1b42ae6d4355328dc4406b6f0188adcf8c566435 (patch)
tree054e44f46fd7c2c4b25e4a7d40313879c5a4bffd
parent949be0f7be8de0c5a6a46626bd983f7a03a4b26e (diff)
downloadlinux-1b42ae6d4355328dc4406b6f0188adcf8c566435.tar.xz
USB: fix race in HCD removal
This patch (as865) fixes a race in the HCD removal code discovered by Milan Plzik. Arrival of an interrupt after the root hub was unregistered could cause the root-hub status timer to start up, even after it was supposed to have been shut down. The problem is fixed by moving the del_timer_sync() call to after the HCD's stop() method, at which time IRQ generation should be disabled. Cc: Milan Plzik <milan.plzik@gmail.com> Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/usb/core/hcd.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index b26c19e..af7aed1 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -544,6 +544,8 @@ void usb_hcd_poll_rh_status(struct usb_hcd *hcd)
unsigned long flags;
char buffer[4]; /* Any root hubs with > 31 ports? */
+ if (unlikely(!hcd->rh_registered))
+ return;
if (!hcd->uses_new_polling && !hcd->status_urb)
return;
@@ -1670,12 +1672,12 @@ void usb_remove_hcd(struct usb_hcd *hcd)
usb_disconnect(&hcd->self.root_hub);
mutex_unlock(&usb_bus_list_lock);
- hcd->poll_rh = 0;
- del_timer_sync(&hcd->rh_timer);
-
hcd->driver->stop(hcd);
hcd->state = HC_STATE_HALT;
+ hcd->poll_rh = 0;
+ del_timer_sync(&hcd->rh_timer);
+
if (hcd->irq >= 0)
free_irq(hcd->irq, hcd);
usb_deregister_bus(&hcd->self);