netdev - RE: [Xen PATCH] xen-netback: fix error handling output

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Date:   Tue, 8 Nov 2016 13:40:02 +0000
From:   Paul Durrant <Paul.Durrant@...rix.com>
To:     Arnd Bergmann <arnd@...db.de>,
        David Vrabel <david.vrabel@...rix.com>
CC:     Wei Liu <wei.liu2@...rix.com>,
        "David S. Miller" <davem@...emloft.net>,
        Juergen Gross <jgross@...e.com>,
        Filipe Manco <filipe.manco@...lab.eu>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [Xen PATCH] xen-netback: fix error handling output

> -----Original Message-----
> From: Arnd Bergmann [mailto:arnd@...db.de]
> Sent: 08 November 2016 13:35
> To: David Vrabel <david.vrabel@...rix.com>
> Cc: Arnd Bergmann <arnd@...db.de>; Wei Liu <wei.liu2@...rix.com>; Paul
> Durrant <Paul.Durrant@...rix.com>; David S. Miller
> <davem@...emloft.net>; Juergen Gross <jgross@...e.com>; Filipe Manco
> <filipe.manco@...lab.eu>; xen-devel@...ts.xenproject.org;
> netdev@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: [Xen PATCH] xen-netback: fix error handling output
> 
> The connect function prints an unintialized error code after an
> earlier initialization was removed:
> 
> drivers/net/xen-netback/xenbus.c: In function 'connect':
> drivers/net/xen-netback/xenbus.c:938:3: error: 'err' may be used
> uninitialized in this function [-Werror=maybe-uninitialized]
> 
> This prints it as -EINVAL instead, which seems to be the most
> appropriate error code. Before the patch that caused the warning,
> this would print a positive number returned by vsscanf() instead,
> which is also wrong. We probably don't need a backport though,
> as fixing the warning here should be sufficient.
> 
> Fixes: f95842e7a9f2 ("xen: make use of xenbus_read_unsigned() in xen-
> netback")
> Fixes: 8d3d53b3e433 ("xen-netback: Add support for multiple queues")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Yes, I'd say EINVAL was most appropriate.

Reviewed-by: Paul Durrant <paul.durrant@...rix.com>

> ---
>  drivers/net/xen-netback/xenbus.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-
> netback/xenbus.c
> index 7356e00fac54..bfed79877b8a 100644
> --- a/drivers/net/xen-netback/xenbus.c
> +++ b/drivers/net/xen-netback/xenbus.c
> @@ -935,7 +935,7 @@ static void connect(struct backend_info *be)
>  					"multi-queue-num-queues", 1);
>  	if (requested_num_queues > xenvif_max_queues) {
>  		/* buggy or malicious guest */
> -		xenbus_dev_fatal(dev, err,
> +		xenbus_dev_fatal(dev, -EINVAL,
>  				 "guest requested %u queues, exceeding the
> maximum of %u.",
>  				 requested_num_queues,
> xenvif_max_queues);
>  		return;
> --
> 2.9.0