linux-kernel - [PATCH] atm: firestream: Replace GFP_ATOMIC with GFP_KERNEL in fs

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Date:   Fri, 26 Jan 2018 16:00:27 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     3chas3@...il.com
Cc:     linux-atm-general@...ts.sourceforge.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH] atm: firestream: Replace GFP_ATOMIC with GFP_KERNEL in fs_send

After checking all possible call chains to fs_send() here,
my tool finds that fs_send() is never called in atomic context.
And this function is assigned to a function pointer "dev->ops->send",
which is only called by vcc_sendmsg() (net/atm/common.c)
through vcc->dev->ops->send(), and vcc_sendmsg() calls schedule(),
it indicates that fs_send() can call functions which may sleep.
Thus GFP_ATOMIC is not necessary, and it can be replaced with GFP_KERNEL.

This is found by a static analysis tool named DCNS written by myself.

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

diff --git a/drivers/atm/firestream.c b/drivers/atm/firestream.c
index d97c056..cce6f9f 100644
--- a/drivers/atm/firestream.c
+++ b/drivers/atm/firestream.c
@@ -1184,7 +1184,7 @@ static int fs_send (struct atm_vcc *atm_vcc, struct sk_buff *skb)

 	vcc->last_skb = skb;

-	td = kmalloc (sizeof (struct FS_BPENTRY), GFP_ATOMIC);
+	td = kmalloc (sizeof (struct FS_BPENTRY), GFP_KERNEL);
 	fs_dprintk (FS_DEBUG_ALLOC, "Alloc transd: %p(%zd)\n", td, sizeof (struct FS_BPENTRY));
 	if (!td) {
 		/* Oops out of mem */
-- 
1.7.9.5