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USB: kill URBs permanently

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looking at usb_kill_urb() it seems to me that it is unnecessarily lenient.
In the use case of disconnect() you never want to use the URB again
(for the same device) But leaving urb->reject elevated will make it easier
to avoid races between read/write and disconnect.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Oliver Neukum 2008-07-29 15:26:15 +02:00 committed by Greg Kroah-Hartman
parent 49b707b90c
commit 55b447bf79
2 changed files with 52 additions and 6 deletions
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56
drivers/usb/core/urb.c
View file

@ -522,6 +522,7 @@ int usb_unlink_urb(struct urb *urb)
}
EXPORT_SYMBOL_GPL(usb_unlink_urb);
static DEFINE_MUTEX(usb_reject_mutex);
/**
* usb_kill_urb - cancel a transfer request and wait for it to finish
* @urb: pointer to URB describing a previously submitted request,
@ -544,24 +545,67 @@ EXPORT_SYMBOL_GPL(usb_unlink_urb);
*/
void usb_kill_urb(struct urb *urb)
{
static DEFINE_MUTEX(reject_mutex);
might_sleep();
if (!(urb && urb->dev && urb->ep))
return;
mutex_lock(&reject_mutex);
mutex_lock(&usb_reject_mutex);
++urb->reject;
mutex_unlock(&reject_mutex);
mutex_unlock(&usb_reject_mutex);
usb_hcd_unlink_urb(urb, -ENOENT);
wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
mutex_lock(&reject_mutex);
mutex_lock(&usb_reject_mutex);
--urb->reject;
mutex_unlock(&reject_mutex);
mutex_unlock(&usb_reject_mutex);
}
EXPORT_SYMBOL_GPL(usb_kill_urb);
/**
* usb_poison_urb - reliably kill a transfer and prevent further use of an URB
* @urb: pointer to URB describing a previously submitted request,
* may be NULL
*
* This routine cancels an in-progress request. It is guaranteed that
* upon return all completion handlers will have finished and the URB
* will be totally idle and cannot be reused. These features make
* this an ideal way to stop I/O in a disconnect() callback.
* If the request has not already finished or been unlinked
* the completion handler will see urb->status == -ENOENT.
*
* After and while the routine runs, attempts to resubmit the URB will fail
* with error -EPERM. Thus even if the URB's completion handler always
* tries to resubmit, it will not succeed and the URB will become idle.
*
* This routine may not be used in an interrupt context (such as a bottom
* half or a completion handler), or when holding a spinlock, or in other
* situations where the caller can't schedule().
*/
void usb_poison_urb(struct urb *urb)
{
might_sleep();
if (!(urb && urb->dev && urb->ep))
return;
mutex_lock(&usb_reject_mutex);
++urb->reject;
mutex_unlock(&usb_reject_mutex);
usb_hcd_unlink_urb(urb, -ENOENT);
wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
}
EXPORT_SYMBOL_GPL(usb_poison_urb);
void usb_unpoison_urb(struct urb *urb)
{
if (!urb)
return;
mutex_lock(&usb_reject_mutex);
--urb->reject;
mutex_unlock(&usb_reject_mutex);
}
EXPORT_SYMBOL_GPL(usb_unpoison_urb);
/**
* usb_kill_anchored_urbs - cancel transfer requests en masse
* @anchor: anchor the requests are bound to

2
include/linux/usb.h
View file

@ -1459,6 +1459,8 @@ extern struct urb *usb_get_urb(struct urb *urb);
extern int usb_submit_urb(struct urb *urb, gfp_t mem_flags);
extern int usb_unlink_urb(struct urb *urb);
extern void usb_kill_urb(struct urb *urb);
extern void usb_poison_urb(struct urb *urb);
extern void usb_unpoison_urb(struct urb *urb);
extern void usb_kill_anchored_urbs(struct usb_anchor *anchor);
extern void usb_unlink_anchored_urbs(struct usb_anchor *anchor);
extern void usb_anchor_urb(struct urb *urb, struct usb_anchor *anchor);