linux-kernel - Re: [PATCH] tty: n_gsm: Debug output allocation must use GFP

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Message-ID: <87sfoxyby9.fsf@BL-laptop>
Date:   Wed, 25 May 2022 15:32:46 +0200
From:   Gregory CLEMENT <gregory.clement@...tlin.com>
To:     Tony Lindgren <tony@...mide.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Daniel Starke <daniel.starke@...mens.com>,
        Jiri Slaby <jirislaby@...nel.org>,
        Johan Hovold <johan@...nel.org>,
        Zhenguo Zhao <Zhenguo.Zhao1@...soc.com>,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: Re: [PATCH] tty: n_gsm: Debug output allocation must use GFP_ATOMIC

Tony Lindgren <tony@...mide.com> writes:

> Dan Carpenter <dan.carpenter@...cle.com> reported the following Smatch
> warning:
>
> drivers/tty/n_gsm.c:720 gsm_data_kick()
> warn: sleeping in atomic context
>
> This is because gsm_control_message() is holding a spin lock so
> gsm_hex_dump_bytes() needs to use GFP_ATOMIC instead of GFP_KERNEL.
>
> Fixes: 925ea0fa5277 ("tty: n_gsm: Fix packet data hex dump output")
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> Signed-off-by: Tony Lindgren <tony@...mide.com>


Reviewed-by: Gregory CLEMENT <gregory.clement@...tlin.com>


> ---
>  drivers/tty/n_gsm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
> --- a/drivers/tty/n_gsm.c
> +++ b/drivers/tty/n_gsm.c
> @@ -459,7 +459,7 @@ static void gsm_hex_dump_bytes(const char *fname, const u8 *data,
>  		return;
>  	}
>  
> -	prefix = kasprintf(GFP_KERNEL, "%s: ", fname);
> +	prefix = kasprintf(GFP_ATOMIC, "%s: ", fname);
>  	if (!prefix)
>  		return;
>  	print_hex_dump(KERN_INFO, prefix, DUMP_PREFIX_OFFSET, 16, 1, data, len,
> -- 
> 2.36.1

-- 
Gregory Clement, Bootlin
Embedded Linux and Kernel engineering
http://bootlin.com