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SubjectRe: [PATCH v4 1/2] usbip: give back URBs for unsent unlink requests during cleanup
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On 8/20/21 1:01 PM, Anirudh Rayabharam wrote:
> In vhci_device_unlink_cleanup(), the URBs for unsent unlink requests are
> not given back. This sometimes causes usb_kill_urb to wait indefinitely
> for that urb to be given back. syzbot has reported a hung task issue [1]
> for this.
>
> To fix this, give back the urbs corresponding to unsent unlink requests
> (unlink_tx list) similar to how urbs corresponding to unanswered unlink
> requests (unlink_rx list) are given back.
>
> [1]: https://syzkaller.appspot.com/bug?id=08f12df95ae7da69814e64eb5515d5a85ed06b76
>
> Reported-by: syzbot+74d6ef051d3d2eacf428@syzkaller.appspotmail.com
> Tested-by: syzbot+74d6ef051d3d2eacf428@syzkaller.appspotmail.com
> Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.com>
> ---
> drivers/usb/usbip/vhci_hcd.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c
> index 4ba6bcdaa8e9..190bd3d1c1f0 100644
> --- a/drivers/usb/usbip/vhci_hcd.c
> +++ b/drivers/usb/usbip/vhci_hcd.c
> @@ -957,8 +957,32 @@ static void vhci_device_unlink_cleanup(struct vhci_device *vdev)
> spin_lock(&vdev->priv_lock);
>
> list_for_each_entry_safe(unlink, tmp, &vdev->unlink_tx, list) {
> + struct urb *urb;
> +
> + /* give back urb of unsent unlink request */
> pr_info("unlink cleanup tx %lu\n", unlink->unlink_seqnum);
> +
> + urb = pickup_urb_and_free_priv(vdev, unlink->unlink_seqnum);
> + if (!urb) {
> + list_del(&unlink->list);
> + kfree(unlink);
> + continue;
> + }
> +
> + urb->status = -ENODEV;
> +
> + usb_hcd_unlink_urb_from_ep(hcd, urb);
> +
> list_del(&unlink->list);
> +
> + spin_unlock(&vdev->priv_lock);
> + spin_unlock_irqrestore(&vhci->lock, flags);
> +
> + usb_hcd_giveback_urb(hcd, urb, urb->status);
> +
> + spin_lock_irqsave(&vhci->lock, flags);
> + spin_lock(&vdev->priv_lock);
> +
> kfree(unlink);
> }
>
>

Looks good.

Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>

thanks,
-- Shuah

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