linux-kernel - Re: [PATCH] mei: vsc: Cast tx_buf to (__be32 *) when passed to cpu_to_be32

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Message-ID: <aBtHDKB6FbIkBS_J@kekkonen.localdomain>
Date: Wed, 7 May 2025 11:42:04 +0000
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: Hans de Goede <hdegoede@...hat.com>
Cc: Wentong Wu <wentong.wu@...el.com>,
	Alexander Usyskin <alexander.usyskin@...el.com>,
	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Stanislaw Gruszka <stanislaw.gruszka@...ux.intel.com>,
	linux-kernel@...r.kernel.org, kernel test robot <lkp@...el.com>
Subject: Re: [PATCH] mei: vsc: Cast tx_buf to (__be32 *) when passed to
 cpu_to_be32_array()

Hi Hans,

On Wed, May 07, 2025 at 11:07:28AM +0200, Hans de Goede wrote:
> Commit f88c0c72ffb0 ("mei: vsc: Use struct vsc_tp_packet as vsc-tp tx_buf
> and rx_buf type") changed the type of tx_buf from "void *" to "struct
> vsc_tp_packet *" and added a cast to (u32 *) when passing it to
> cpu_to_be32_array() and the same change was made for rx_buf.
> 
> This triggers the type-check warning in sparse:
> 
> vsc-tp.c:327:28: sparse: expected restricted __be32 [usertype] *dst
> vsc-tp.c:327:28: sparse: got unsigned int [usertype] *
> 
> vsc-tp.c:343:42: sparse: expected restricted __be32 const [usertype] *src
> vsc-tp.c:343:42: sparse: got unsigned int [usertype] *
> 
> Fix this by casting to (__be32 *) instead.
> 
> Note actually changing the type of the buffers to "be32 *" is not an option
> this buffer does actually contain a "struct vsc_tp_packet" and is used
> as such most of the time. vsc_tp_rom_xfer() re-uses the buffers as just
> dumb arrays of 32 bit words to talk to the device before the firmware has
> booted, to avoid needing to allocate a separate buffer.
> 
> Fixes: f88c0c72ffb0 ("mei: vsc: Use struct vsc_tp_packet as vsc-tp tx_buf and rx_buf type")
> Reported-by: kernel test robot <lkp@...el.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202505071634.kZ0I7Va6-lkp@intel.com/
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>

Thanks!

Reviewed-by: Sakari Ailus <sakari.ailus@...ux.intel.com>

> ---
>  drivers/misc/mei/vsc-tp.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/misc/mei/vsc-tp.c b/drivers/misc/mei/vsc-tp.c
> index da26a080916c..267d0de5fade 100644
> --- a/drivers/misc/mei/vsc-tp.c
> +++ b/drivers/misc/mei/vsc-tp.c
> @@ -324,7 +324,7 @@ int vsc_tp_rom_xfer(struct vsc_tp *tp, const void *obuf, void *ibuf, size_t len)
>  	guard(mutex)(&tp->mutex);
>  
>  	/* rom xfer is big endian */
> -	cpu_to_be32_array((u32 *)tp->tx_buf, obuf, words);
> +	cpu_to_be32_array((__be32 *)tp->tx_buf, obuf, words);
>  
>  	ret = read_poll_timeout(gpiod_get_value_cansleep, ret,
>  				!ret, VSC_TP_ROM_XFER_POLL_DELAY_US,
> @@ -340,7 +340,7 @@ int vsc_tp_rom_xfer(struct vsc_tp *tp, const void *obuf, void *ibuf, size_t len)
>  		return ret;
>  
>  	if (ibuf)
> -		be32_to_cpu_array(ibuf, (u32 *)tp->rx_buf, words);
> +		be32_to_cpu_array(ibuf, (__be32 *)tp->rx_buf, words);
>  
>  	return ret;
>  }

-- 
Regards,

Sakari Ailus