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

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Date:   Mon, 23 May 2022 18:50:52 +0300
From:   Tony Lindgren <tony@...mide.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Daniel Starke <daniel.starke@...mens.com>,
        Gregory CLEMENT <gregory.clement@...tlin.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: [PATCH] tty: n_gsm: Debug output allocation must use GFP_ATOMIC

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>
---
 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