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From: Shuah Khan <skhan@linuxfoundation.org>
To: Anirudh Rayabharam <mail@anirudhrb.com>,
	valentina.manea.m@gmail.com, shuah@kernel.org,
	gregkh@linuxfoundation.org
Cc: syzbot+74d6ef051d3d2eacf428@syzkaller.appspotmail.com,
	linux-kernel-mentees@lists.linuxfoundation.org,
	linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
	Shuah Khan <skhan@linuxfoundation.org>
Subject: Re: [PATCH v3 1/2] usbip: give back URBs for unsent unlink requests during cleanup
Date: Tue, 17 Aug 2021 17:16:51 -0600	[thread overview]
Message-ID: <13450a85-bbfe-09c5-d614-1a944c2600c2@linuxfoundation.org> (raw)
In-Reply-To: <20210813182508.28127-2-mail@anirudhrb.com>

On 8/13/21 12:25 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 | 26 ++++++++++++++++++++++++++
>   1 file changed, 26 insertions(+)
> 
> diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c
> index 4ba6bcdaa8e9..6f3f374d4bbc 100644
> --- a/drivers/usb/usbip/vhci_hcd.c
> +++ b/drivers/usb/usbip/vhci_hcd.c
> @@ -957,8 +957,34 @@ 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);

I know this is an exiting one.
Let's make this pr_debug or remove it all together.

> +
> +		urb = pickup_urb_and_free_priv(vdev, unlink->unlink_seqnum);
> +		if (!urb) {
> +			pr_info("the urb (seqnum %lu) was already given back\n",
> +				unlink->unlink_seqnum);

Let's make this pr_debug or remove it all together.

> +			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);
>   	}
>   
> 

thanks,
-- Shuah

  reply	other threads:[~2021-08-17 23:16 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-13 18:25 [PATCH v3 0/2] Fix syzkaller bug: hung task in hub_port_init Anirudh Rayabharam
2021-08-13 18:25 ` [PATCH v3 1/2] usbip: give back URBs for unsent unlink requests during cleanup Anirudh Rayabharam
2021-08-17 23:16   ` Shuah Khan [this message]
2021-08-18  5:39     ` Greg KH
2021-08-18 18:36       ` Shuah Khan
2021-08-19 18:09         ` Anirudh Rayabharam
2021-08-19 18:49           ` Shuah Khan
2021-08-13 18:25 ` [PATCH v3 2/2] usbip: eliminate duplicate code in vhci_device_unlink_cleanup Anirudh Rayabharam

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