linux-kernel - [PATCH] tty: ipwireless: Replace GFP_ATOMIC with GFP_KERNEL in ipwireless_network

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Date:   Tue, 10 Apr 2018 16:31:46 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     jikos@...nel.org, dsterba@...e.com, gregkh@...uxfoundation.org,
        jslaby@...e.com, johannes.berg@...el.com,
        stephen@...workplumber.org, davem@...emloft.net
Cc:     linux-kernel@...r.kernel.org, Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH] tty: ipwireless: Replace GFP_ATOMIC with GFP_KERNEL in ipwireless_network_create

ipwireless_network_create() is never called in atomic context.

The call chain ending up at ipwireless_network_create() is:
[1] ipwireless_network_create() <- config_ipwireless() <- 
	ipwireless_attach()
ipwireless_attach() is only set as ".probe" in struct pcmcia_driver.

Despite never getting called from atomic context,
ipwireless_network_create() calls kzalloc() with GFP_ATOMIC,
which does not sleep for allocation.
GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
which can sleep and improve the possibility of sucessful allocation.

This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
 drivers/tty/ipwireless/network.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/ipwireless/network.c b/drivers/tty/ipwireless/network.c
index c2f9a32..17b04b5 100644
--- a/drivers/tty/ipwireless/network.c
+++ b/drivers/tty/ipwireless/network.c
@@ -415,7 +415,7 @@ void ipwireless_network_packet_received(struct ipw_network *network,
 struct ipw_network *ipwireless_network_create(struct ipw_hardware *hw)
 {
 	struct ipw_network *network =
-		kzalloc(sizeof(struct ipw_network), GFP_ATOMIC);
+		kzalloc(sizeof(struct ipw_network), GFP_KERNEL);
 
 	if (!network)
 		return NULL;
-- 
1.9.1