Re: [PATCH] spi: rockchip: avoid objtool warning

From: "Heiko Stübner" <heiko@sntech.de>
To: Mark Brown <broonie@kernel.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Emil Renner Berthing <kernel@esmil.dk>,
	Arnd Bergmann <arnd@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>, Jon Lin <jon.lin@rock-chips.com>,
	Chris Ruehl <chris.ruehl@gtsys.com.hk>,
	Alexander Kochetkov <al.kochet@gmail.com>,
	Johan Jonker <jbx6244@gmail.com>,
	Vincent Pelletier <plr.vincent@gmail.com>,
	linux-spi@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org,
	clang-built-linux@googlegroups.com
Subject: Re: [PATCH] spi: rockchip: avoid objtool warning
Date: Thu, 25 Feb 2021 22:19:32 +0100	[thread overview]
Message-ID: <5587539.MhkbZ0Pkbq@diego> (raw)
In-Reply-To: <20210225125541.1808719-1-arnd@kernel.org>

Am Donnerstag, 25. Februar 2021, 13:55:34 CET schrieb Arnd Bergmann:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Building this file with clang leads to a an unreachable code path
> causing a warning from objtool:
> 
> drivers/spi/spi-rockchip.o: warning: objtool: rockchip_spi_transfer_one()+0x2e0: sibling call from callable instruction with modified stack frame
> 
> Use BUG() instead of unreachable() to avoid the undefined behavior
> if it does happen.
> 
> Fixes: 65498c6ae241 ("spi: rockchip: support 4bit words")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Acked-by: Heiko Stuebner <heiko@sntech.de>

> ---
>  drivers/spi/spi-rockchip.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
> index 936ef54e0903..972beac1169a 100644
> --- a/drivers/spi/spi-rockchip.c
> +++ b/drivers/spi/spi-rockchip.c
> @@ -521,7 +521,7 @@ static void rockchip_spi_config(struct rockchip_spi *rs,
>  		 * ctlr->bits_per_word_mask, so this shouldn't
>  		 * happen
>  		 */
> -		unreachable();
> +		BUG();
>  	}
>  
>  	if (use_dma) {
>