[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <2023081413-simmering-snap-bb8e@gregkh>
Date: Mon, 14 Aug 2023 18:04:21 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: Nathan Chancellor <nathan@...nel.org>,
Jiri Slaby <jirislaby@...nel.org>,
Shawn Guo <shawnguo@...nel.org>,
Sascha Hauer <s.hauer@...gutronix.de>,
Pengutronix Kernel Team <kernel@...gutronix.de>,
Fabio Estevam <festevam@...il.com>,
NXP Linux Team <linux-imx@....com>,
linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
Andi Shyti <andi.shyti@...nel.org>
Subject: Re: [PATCH] serial: mxs-uart: fix Wvoid-pointer-to-enum-cast warning
On Mon, Aug 14, 2023 at 08:58:34AM +0200, Krzysztof Kozlowski wrote:
> On 10/08/2023 17:44, Greg Kroah-Hartman wrote:
> > On Thu, Aug 10, 2023 at 10:50:42AM +0200, Krzysztof Kozlowski wrote:
> >> `devtype` is enum, thus cast of pointer on 64-bit compile test with W=1
> >> causes:
> >>
> >> mxs-auart.c:1598:15: error: cast to smaller integer type 'enum mxs_auart_type' from 'const void *' [-Werror,-Wvoid-pointer-to-enum-cast]
> >>
> >> Cc: Andi Shyti <andi.shyti@...nel.org>
> >> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> >> ---
> >> drivers/tty/serial/mxs-auart.c | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
> >> index 8eeecf8ad359..a9b32722b049 100644
> >> --- a/drivers/tty/serial/mxs-auart.c
> >> +++ b/drivers/tty/serial/mxs-auart.c
> >> @@ -1595,7 +1595,7 @@ static int mxs_auart_probe(struct platform_device *pdev)
> >> return -EINVAL;
> >> }
> >>
> >> - s->devtype = (enum mxs_auart_type)of_device_get_match_data(&pdev->dev);
> >> + s->devtype = (uintptr_t)of_device_get_match_data(&pdev->dev);
> >
> > This feels like a compiler issue as devtype is a enum mxs_auart_type
> > variable, so the cast shoudl be correct.
>
> While the cast is obviously safe here, the warning in general is
> reasonable - people were make too many mistakes by assuming pointers are
> integers...
But this isn't a pointer, it's an enumerated type thrown into a void *,
so cast it properly (void * == unsigned long).
> Just for the record (not saying that others doing is proof of correctness):
>
> https://lore.kernel.org/lkml/20230809-cbl-1903-v1-1-df9d66a3ba3e@google.com/T/
>
> But maybe Nathan can share his thoughts whether we should just disable
> this warning for kernel?
I thought that Linus had some objection to the compilers doing something
foolish here as well, but I can't find it in my archives at the moment
(am traveling).
> > And if not, unitptr_t isn't a valid kernel type, so that's not a good
>
> It is in include/linux/types.h, so do you mean that it is not
> recommended for in-kernel usage? I can go with kernel_ulong_t - which is
> a kernel type - if the cast is agreed.
not recommended for in-kernel usage.
thanks,
greg k-h
Powered by blists - more mailing lists