linux-kernel - Re: [PATCH v2] media: cx18: Don't check for address of video

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Message-ID: <CAKwvOdk6Z2und-7U6SVHqKxiEk6Ahpuc8_=O7Os5axx43itp5Q@mail.gmail.com>
Date:   Mon, 1 Oct 2018 16:05:57 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Nathan Chancellor <natechancellor@...il.com>
Cc:     awalls@...metrocast.net,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        hverkuil@...all.nl, linux-media@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] media: cx18: Don't check for address of video_dev

On Mon, Oct 1, 2018 at 8:22 AM Nathan Chancellor
<natechancellor@...il.com> wrote:
>
> Clang warns that the address of a pointer will always evaluated as true
> in a boolean context.
>
> drivers/media/pci/cx18/cx18-driver.c:1255:23: warning: address of
> 'cx->streams[i].video_dev' will always evaluate to 'true'
> [-Wpointer-bool-conversion]
>                 if (&cx->streams[i].video_dev)
>                 ~~   ~~~~~~~~~~~~~~~^~~~~~~~~
> 1 warning generated.
>
> Check whether v4l2_dev is null, not the address, so that the statement
> doesn't fire all the time. This check has been present since 2009,
> introduced by commit 21a278b85d3c ("V4L/DVB (11619): cx18: Simplify the
> work handler for outgoing mailbox commands")
>
> Reported-by: Nick Desaulniers <ndesaulniers@...gle.com>
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
> ---
>
> v1 -> v2:
>
> * Fix build error and logic per review from Hans
>
>  drivers/media/pci/cx18/cx18-driver.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/media/pci/cx18/cx18-driver.c b/drivers/media/pci/cx18/cx18-driver.c
> index 56763c4ea1a7..a6ba4ca5aa91 100644
> --- a/drivers/media/pci/cx18/cx18-driver.c
> +++ b/drivers/media/pci/cx18/cx18-driver.c
> @@ -1252,7 +1252,7 @@ static void cx18_cancel_out_work_orders(struct cx18 *cx)
>  {
>         int i;
>         for (i = 0; i < CX18_MAX_STREAMS; i++)
> -               if (&cx->streams[i].video_dev)
> +               if (cx->streams[i].video_dev.v4l2_dev)

There we go, that looks better!  Thanks for respinning this patch.  I
would've given Hans credit in a Suggested-by tag, but there's not
necessarily strict rules on that (and doesn't necessitate a v3).
Maybe the maintainer could apply that to the commit message when
applying?  Either way:

Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>

>                         cancel_work_sync(&cx->streams[i].out_work_order);
>  }
>
> --
> 2.19.0
>


-- 
Thanks,
~Nick Desaulniers