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usb/core: remove "always" from usb_unlink_urb() kernel doc entry

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The kernel doc entry for usb_unlink_urb() contains the phrase "This
request is always asynchronous.". The "always" leads to the assumption
that the ->complete() callback is not called from within
usb_unlink_urb(). This is not true. The HCD is allowed to call the
->complete() from within ->urb_dequeue() if it is appropriate for the
hardware.
This patch updates the kernel doc so usb-device driver authors make sure
to drop all locks (and make sure it is okay to drop them) which are
acquired by the complete callback before calling usb_unlink_urb().

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sebastian Andrzej Siewior 2012-02-29 23:04:32 +01:00 committed by Greg Kroah-Hartman
parent 2a5be8783e
commit 371f3b49f2
1 changed files with 7 additions and 4 deletions
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11
drivers/usb/core/urb.c
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@ -527,10 +527,13 @@ EXPORT_SYMBOL_GPL(usb_submit_urb);
* a driver's I/O routines to insure that all URB-related activity has
* completed before it returns.
*
* This request is always asynchronous. Success is indicated by
* returning -EINPROGRESS, at which time the URB will probably not yet
* have been given back to the device driver. When it is eventually
* called, the completion function will see @urb->status == -ECONNRESET.
* This request is asynchronous, however the HCD might call the ->complete()
* callback during unlink. Therefore when drivers call usb_unlink_urb(), they
* must not hold any locks that may be taken by the completion function.
* Success is indicated by returning -EINPROGRESS, at which time the URB will
* probably not yet have been given back to the device driver. When it is
* eventually called, the completion function will see @urb->status ==
* -ECONNRESET.
* Failure is indicated by usb_unlink_urb() returning any other value.
* Unlinking will fail when @urb is not currently "linked" (i.e., it was
* never submitted, or it was unlinked before, or the hardware is already