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USB: gadgetfs AIO tweaks

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This patch (as837) fixes several mistakes in the AIO interface of the
gadgetfs driver:

	The ki_retry method is not supposed to do a put on the kiocb.
	The extra call to aio_put_req() causes memory corruption.
	(Note: This call was removed before, by patch as691, and then
	mysteriously re-introduced later.)

	Even if a read transfer is cancelled, we can and should send
	to the user all the data that did manage to get transferred.

	Testing for AIO cancellation in the I/O completion handler
	is both racy and (now) unnecessary.  aio_complete() does its
	own checking, in a safe manner.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2007-01-16 23:28:48 -08:00 committed by Greg Kroah-Hartman
parent ce46794f77
commit 49631ca7f3
1 changed files with 7 additions and 9 deletions
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16
drivers/usb/gadget/inode.c
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@ -576,7 +576,6 @@ static ssize_t ep_aio_read_retry(struct kiocb *iocb)
}
kfree(priv->buf);
kfree(priv);
aio_put_req(iocb);
return len;
}
@ -590,18 +589,17 @@ static void ep_aio_complete(struct usb_ep *ep, struct usb_request *req)
spin_lock(&epdata->dev->lock);
priv->req = NULL;
priv->epdata = NULL;
if (priv->iv == NULL
|| unlikely(req->actual == 0)
|| unlikely(kiocbIsCancelled(iocb))) {
/* if this was a write or a read returning no data then we
* don't need to copy anything to userspace, so we can
* complete the aio request immediately.
*/
if (priv->iv == NULL || unlikely(req->actual == 0)) {
kfree(req->buf);
kfree(priv);
iocb->private = NULL;
/* aio_complete() reports bytes-transferred _and_ faults */
if (unlikely(kiocbIsCancelled(iocb)))
aio_put_req(iocb);
else
aio_complete(iocb,
req->actual ? req->actual : req->status,
aio_complete(iocb, req->actual ? req->actual : req->status,
req->status);
} else {
/* retry() won't report both; so we hide some faults */