Re: [PATCH] media: cx18: Don't check for address of video_dev

From: Nick Desaulniers
Date: Fri Sep 21 2018 - 16:31:52 EST


On Fri, Sep 21, 2018 at 1:03 PM Nathan Chancellor
<natechancellor@xxxxxxxxx> 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.
>
> Presumably, the contents of video_dev should have been checked, not the
> address. 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@xxxxxxxxxx>
> Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
> ---
>
> Alternatively, this if statement could just be removed since it has
> evaluated to true since 2009 and I assume some issue with this would
> have been discovered by now.
>
> 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..753a37c7100a 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)

cx->streams[i].video_dev has the type `struct video_device video_dev`.
So wouldn't this change always be true as well, since the struct is
embedded?

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


--
Thanks,
~Nick Desaulniers