linux-kernel - [PATCH] net: usb: hso: Replace GFP_ATOMIC with GFP_KERNEL in hso_create

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Date:   Tue, 10 Apr 2018 22:35:24 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     davem@...emloft.net, andreas@...nade.info, johan@...nel.org,
        johannes.berg@...el.com, stephen@...workplumber.org,
        Linyu.Yuan@...atel-sbell.com.cn
Cc:     linux-usb@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH] net: usb: hso: Replace GFP_ATOMIC with GFP_KERNEL in hso_create_device

hso_create_device() is never called in atomic context.

The call chains ending up at hso_create_device() are:
[1] hso_create_device() <- hso_create_bulk_serial_device() <- hso_probe()
[2] hso_create_device() <- hso_create_mux_serial_device() <- hso_probe()
[3] hso_create_device() <- hso_create_net_device() <- hso_probe()
hso_probe() is set as ".probe" in struct usb_driver, 
so it is not called in atomic context.

Despite never getting called from atomic context,
hso_create_device() 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/net/usb/hso.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index d7a3379..3d7a33f 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -2332,7 +2332,7 @@ static struct hso_device *hso_create_device(struct usb_interface *intf,
 {
 	struct hso_device *hso_dev;

-	hso_dev = kzalloc(sizeof(*hso_dev), GFP_ATOMIC);
+	hso_dev = kzalloc(sizeof(*hso_dev), GFP_KERNEL);
 	if (!hso_dev)
 		return NULL;

-- 
1.9.1