netdev - Re: [PATCH] xen-netback: correctly check failed allocation

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Message-ID: <20151016092831.GK32638@zion.uk.xensource.com>
Date:	Fri, 16 Oct 2015 10:28:31 +0100
From:	Wei Liu <wei.liu2@...rix.com>
To:	Insu Yun <wuninsu@...il.com>
CC:	Ian Campbell <ian.campbell@...rix.com>,
	Wei Liu <wei.liu2@...rix.com>,
	<xen-devel@...ts.xenproject.org>, <netdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Taesoo Kim <taesoo@...ech.edu>,
	Yeongjin Jang <yeongjin.jang@...ech.edu>,
	"Yun, Insu" <insu@...ech.edu>
Subject: Re: [PATCH] xen-netback: correctly check failed allocation

On Fri, Oct 16, 2015 at 10:05:21AM +0100, Wei Liu wrote:
> On Thu, Oct 15, 2015 at 02:02:47PM -0400, Insu Yun wrote:
> > I changed patch with valid format.
> > 
> > On Thu, Oct 15, 2015 at 2:02 PM, Insu Yun <wuninsu@...il.com> wrote:
> > 
> > > Since vzalloc can be failed in memory pressure,
> > > writes -ENOMEM to xenstore to indicate error.
> > >
> > > Signed-off-by: Insu Yun <wuninsu@...il.com>
> > > ---
> > >  drivers/net/xen-netback/xenbus.c | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > >
> > > diff --git a/drivers/net/xen-netback/xenbus.c
> > > b/drivers/net/xen-netback/xenbus.c
> > > index 929a6e7..56ebd82 100644
> > > --- a/drivers/net/xen-netback/xenbus.c
> > > +++ b/drivers/net/xen-netback/xenbus.c
> > > @@ -788,6 +788,12 @@ static void connect(struct backend_info *be)
> > >         /* Use the number of queues requested by the frontend */
> > >         be->vif->queues = vzalloc(requested_num_queues *
> > >                                   sizeof(struct xenvif_queue));
> > > +       if (!be->vif->queues) {
> > > +               xenbus_dev_fatal(dev, -ENOMEM,
> > > +                                "allocating queues");
> > > +               return;
> > >
> > 
> > I didn't use goto err, because another error handling is not required
> > 
> 
> It's recommended in kernel coding style to use "goto" style error
> handling. I personally prefer that to arbitrary return in function body,
> too.
> 
> It's not a matter of whether another error handling is required or not,
> it's about cleaner code that is easy to reason about and consistent
> coding style.
> 
> The existing code is not perfect, but that doesn't mean we should follow
> bad example.

And to be clear, I don't want to block this patch just because of this
coding style thing.  It's still an improvement and fix a real problem.
So:

Acked-by: Wei Liu <wei.liu2@...rix.com>
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