From 5da43afc2b73795e82c4bc3e53a4a177a02637d0 Mon Sep 17 00:00:00 2001 From: Thomas Pugliese Date: Fri, 28 Feb 2014 14:31:57 -0600 Subject: usb: wusbcore: prevent urb dequeue and giveback race This patch takes a reference to the wa_xfer object in wa_urb_dequeue to prevent the urb giveback code from completing the xfer and freeing it while wa_urb_dequeue is executing. It also checks for done at the start to avoid a double completion scenario. Adding the check for done in urb_dequeue means that any other place where a submitted transfer segment is marked as done must complete the transfer if it is done. __wa_xfer_delayed_run was not checking this case so that check was added as well. Signed-off-by: Thomas Pugliese Signed-off-by: Greg Kroah-Hartman --- drivers/usb/wusbcore/wa-xfer.c | 37 +++++++++++++++++++++++++++---------- 1 file changed, 27 insertions(+), 10 deletions(-) (limited to 'drivers/usb/wusbcore') diff --git a/drivers/usb/wusbcore/wa-xfer.c b/drivers/usb/wusbcore/wa-xfer.c index cb061915f051..5e5343e69915 100644 --- a/drivers/usb/wusbcore/wa-xfer.c +++ b/drivers/usb/wusbcore/wa-xfer.c @@ -1471,6 +1471,8 @@ static int __wa_xfer_delayed_run(struct wa_rpipe *rpipe, int *dto_waiting) xfer, wa_xfer_id(xfer), seg->index, atomic_read(&rpipe->segs_available), result); if (unlikely(result < 0)) { + int done; + spin_unlock_irqrestore(&rpipe->seg_lock, flags); spin_lock_irqsave(&xfer->lock, flags); __wa_xfer_abort(xfer); @@ -1479,7 +1481,10 @@ static int __wa_xfer_delayed_run(struct wa_rpipe *rpipe, int *dto_waiting) * the RPIPE seg_list. Mark it done. */ xfer->segs_done++; + done = __wa_xfer_is_done(xfer); spin_unlock_irqrestore(&xfer->lock, flags); + if (done) + wa_xfer_completion(xfer); spin_lock_irqsave(&rpipe->seg_lock, flags); } wa_xfer_put(xfer); @@ -1915,20 +1920,20 @@ int wa_urb_dequeue(struct wahc *wa, struct urb *urb, int status) /* check if it is safe to unlink. */ spin_lock_irqsave(&wa->xfer_list_lock, flags); result = usb_hcd_check_unlink_urb(&(wa->wusb->usb_hcd), urb, status); + if ((result == 0) && urb->hcpriv) { + /* + * Get a xfer ref to prevent a race with wa_xfer_giveback + * cleaning up the xfer while we are working with it. + */ + wa_xfer_get(urb->hcpriv); + } spin_unlock_irqrestore(&wa->xfer_list_lock, flags); if (result) return result; xfer = urb->hcpriv; - if (xfer == NULL) { - /* - * Nothing setup yet enqueue will see urb->status != - * -EINPROGRESS (by hcd layer) and bail out with - * error, no need to do completion - */ - BUG_ON(urb->status == -EINPROGRESS); - goto out; - } + if (xfer == NULL) + return -ENOENT; spin_lock_irqsave(&xfer->lock, flags); pr_debug("%s: DEQUEUE xfer id 0x%08X\n", __func__, wa_xfer_id(xfer)); rpipe = xfer->ep->hcpriv; @@ -1939,6 +1944,16 @@ int wa_urb_dequeue(struct wahc *wa, struct urb *urb, int status) result = -ENOENT; goto out_unlock; } + /* + * Check for done to avoid racing with wa_xfer_giveback and completing + * twice. + */ + if (__wa_xfer_is_done(xfer)) { + pr_debug("%s: xfer %p id 0x%08X already done.\n", __func__, + xfer, wa_xfer_id(xfer)); + result = -ENOENT; + goto out_unlock; + } /* Check the delayed list -> if there, release and complete */ spin_lock_irqsave(&wa->xfer_list_lock, flags2); if (!list_empty(&xfer->list_node) && xfer->seg == NULL) @@ -2007,11 +2022,12 @@ int wa_urb_dequeue(struct wahc *wa, struct urb *urb, int status) wa_xfer_completion(xfer); if (rpipe_ready) wa_xfer_delayed_run(rpipe); + wa_xfer_put(xfer); return result; out_unlock: spin_unlock_irqrestore(&xfer->lock, flags); -out: + wa_xfer_put(xfer); return result; dequeue_delayed: @@ -2020,6 +2036,7 @@ dequeue_delayed: xfer->result = urb->status; spin_unlock_irqrestore(&xfer->lock, flags); wa_xfer_giveback(xfer); + wa_xfer_put(xfer); usb_put_urb(urb); /* we got a ref in enqueue() */ return 0; } -- cgit