linux-kernel - Re: [PATCH 4/4] usb: xhci: warn on command timeout in stopped command ring

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Message-ID: <dd963149-d0bb-8177-1608-94eb86e4d4a3@cogentembedded.com>
Date:   Fri, 23 Dec 2016 12:49:32 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>,
        Mathias Nyman <mathias.nyman@...ux.intel.com>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] usb: xhci: warn on command timeout in stopped command
 ring

Hello!

On 12/23/2016 9:52 AM, Lu Baolu wrote:

> If xhci host fails to response to a command, the command

    s/response/respond/.

> watchdog timer will be fired. The callback function will
> abort and clear current command and restart the command
> execution. If driver fails to restart command execution,
> it will assume there is a larger problem in host and
> report the situation to the upper layer. In rare cases,
> if the driver sees a command timeout in a stopped command
> ring, driver should let the user know it.
>
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
>  drivers/usb/host/xhci-ring.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> index 6a23c37..16baefc 100644
> --- a/drivers/usb/host/xhci-ring.c
> +++ b/drivers/usb/host/xhci-ring.c
> @@ -1308,8 +1308,12 @@ void xhci_handle_command_timeout(struct work_struct *work)
>  		goto time_out_completed;
>  	}
>
> -	/* command timeout on stopped ring, ring can't be aborted */
> -	xhci_dbg(xhci, "Command timeout on stopped ring\n");
> +	/*
> +	 * We should never reach here until a command times out on a stopped
> +	 * ring and xhci driver has no idea about the reason why the command
> +	 * ring was stopped.
> +	 */
> +	xhci_warn(xhci, "WARN command timeout on stopped ring\n");

    WARNING, maybe?

[...]

MBR, Sergei