linux-kernel - Re: [PATCH] drm/virtio: remove some redundant code

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Message-ID: <b82057bf-3126-4721-87f5-79ca3682cee4@kadam.mountain>
Date:   Wed, 12 Jul 2023 09:36:41 +0300
From:   Dan Carpenter <dan.carpenter@...aro.org>
To:     Su Hui <suhui@...china.com>
Cc:     airlied@...hat.com, kraxel@...hat.com, gurchetansingh@...omium.org,
        olvaffe@...il.com, daniel@...ll.ch,
        dri-devel@...ts.freedesktop.org,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] drm/virtio: remove some redundant code

On Wed, Jul 12, 2023 at 09:18:42AM +0800, Su Hui wrote:
> On 2023/7/11 19:13, Dan Carpenter wrote:
> > On Tue, Jul 11, 2023 at 05:00:31PM +0800, Su Hui wrote:
> > > virtio_gpu_get_vbuf always be successful,
> > > so remove the error judgment.
> > > 
> > No, just ignore the static checker false positive in this case.  The
> > intent of the code is clear that if it did have an error it should
> > return an error pointer.
> 
> Hi, Dan,
> 
> Function "virtio_gpu_get_vbuf" call "kmem_cache_zalloc (vgdev->vbufs,
> GFP_KERNEL | __GFP_NOFAIL)" to
> allocate memory. Adding the " __GFP_NOFAIL”flag make sure it won't fail. And
> "virtio_gpu_get_vbuf" never
> return an error code, so I think this is not a false positive.

We all see this and agree.

However the check for if (IS_ERR()) is written deliberately because we
might change the code to return error pointers in the future.  Static
checkers are looking for code that does something unintentional but in
this case the code was written that way deliberately.

regards,
dan carpenter