diff options
| author | Alan Stern <stern@rowland.harvard.edu> | 2012-03-28 16:13:28 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-04-06 13:54:00 -0700 |
| commit | da8bfb090c2b30af9f3879443355f7eb1d0fe10a (patch) | |
| tree | 377d67c3c0cc1ad40d7357f821712c4c9ba6c639 /drivers/usb/core | |
| parent | bcf398537630bf20b4dbe59ba855b69f404c93cf (diff) | |
| download | linux-da8bfb090c2b30af9f3879443355f7eb1d0fe10a.tar.gz | |
USB documentation: explain lifetime rules for unlinking URBs
This patch (as1534c) updates the documentation for usb_unlink_urb and
related functions. It explains that the caller must prevent the URB
being unlinked from getting deallocated while the unlink is taking
place.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/core')
| -rw-r--r-- | drivers/usb/core/urb.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c index 7239a73c1b8c..cd9b3a2cd8a7 100644 --- a/drivers/usb/core/urb.c +++ b/drivers/usb/core/urb.c @@ -539,6 +539,10 @@ EXPORT_SYMBOL_GPL(usb_submit_urb); * never submitted, or it was unlinked before, or the hardware is already * finished with it), even if the completion handler has not yet run. * + * The URB must not be deallocated while this routine is running. In + * particular, when a driver calls this routine, it must insure that the + * completion handler cannot deallocate the URB. + * * Unlinking and Endpoint Queues: * * [The behaviors and guarantees described below do not apply to virtual @@ -603,6 +607,10 @@ EXPORT_SYMBOL_GPL(usb_unlink_urb); * 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. * + * The URB must not be deallocated while this routine is running. In + * particular, when a driver calls this routine, it must insure that the + * completion handler cannot deallocate the URB. + * * 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(). @@ -640,6 +648,10 @@ EXPORT_SYMBOL_GPL(usb_kill_urb); * 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. * + * The URB must not be deallocated while this routine is running. In + * particular, when a driver calls this routine, it must insure that the + * completion handler cannot deallocate the URB. + * * 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(). |