From david-b@pacbell.net Tue Jan 16 23:28:58 2007 From: Alan Stern Date: Tue, 16 Jan 2007 23:28:48 -0800 Subject: USB: gadgetfs AIO tweaks To: Greg KH Cc: Alan Stern Message-ID: <200701162328.49291.david-b@pacbell.net> Content-Disposition: inline From: Alan Stern 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 Signed-off-by: David Brownell Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/inode.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) --- gregkh-2.6.orig/drivers/usb/gadget/inode.c +++ gregkh-2.6/drivers/usb/gadget/inode.c @@ -576,7 +576,6 @@ static ssize_t ep_aio_read_retry(struct } kfree(priv->buf); kfree(priv); - aio_put_req(iocb); return len; } @@ -590,18 +589,17 @@ static void ep_aio_complete(struct usb_e 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 */