linux-kernel - Re: [PATCH v5 0/8] xen: dma-buf support for grant device

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Date:   Mon, 23 Jul 2018 18:50:56 +0300
From:   Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Oleksandr Andrushchenko <andr2000@...il.com>,
        xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-media@...r.kernel.org,
        jgross@...e.com, konrad.wilk@...cle.com
Cc:     daniel.vetter@...el.com, dongwon.kim@...el.com,
        matthew.d.roper@...el.com
Subject: Re: [PATCH v5 0/8] xen: dma-buf support for grant device

On 07/23/2018 06:22 PM, Boris Ostrovsky wrote:
> On 07/23/2018 09:26 AM, Oleksandr Andrushchenko wrote:
>> On 07/23/2018 11:38 AM, Oleksandr Andrushchenko wrote:
>>>> data/upstream/linux-xen/drivers/xen/gntdev-dmabuf.c: In function
>>>> ‘gntdev_ioctl_dmabuf_exp_from_refs’:
>>>> /data/upstream/linux-xen/drivers/xen/gntdev-dmabuf.c:503:6: warning:
>>>> ‘args.fd’ may be used uninitialized in this function
>>>> [-Wmaybe-uninitialized]
>>>>     *fd = args.fd;
>>>>     ~~~~^~~~~~~~~
>>>> /data/upstream/linux-xen/drivers/xen/gntdev-dmabuf.c:467:35: note:
>>>> ‘args.fd’ was declared here
>>>>     struct gntdev_dmabuf_export_args args;
>>>>                                      ^~~~
>>> Strangely, but my i386 build goes smooth.
>>> Which version of gcc you use and could you please give me your
>>> .config, so I can test the same?
>> Now I see this warning which seems to be a false positive.
>> Boris, could you please apply the following:
>>
>> diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c
>> index e4c9f1f74476..0680dbcba616 100644
>> --- a/drivers/xen/gntdev-dmabuf.c
>> +++ b/drivers/xen/gntdev-dmabuf.c
>> @@ -495,6 +495,7 @@ static int dmabuf_exp_from_refs(struct gntdev_priv
>> *priv, int flags,
>>          args.dmabuf_priv = priv->dmabuf_priv;
>>          args.count = map->count;
>>          args.pages = map->pages;
>> +       args.fd = -1;
>>
>>          ret = dmabuf_exp_from_pages(&args);
>>          if (ret < 0)
>>
>> or please let me know if you want me to resend with this fix?
>
> Missed this message. Yes, this obviously fixes the problem. And it is
> due to the code fragment that I mentioned in the earlier response.
>
> Which patch is this for? I can add this when committing.
Thank you, this is for "[PATCH v5 7/8] xen/gntdev: Implement dma-buf 
export functionality"
> -boris
Thank you,
Oleksandr