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From:   Jia-Ju Bai <baijiaju1990@gmail.com>
To:     3chas3@gmail.com
Cc:     linux-atm-general@lists.sourceforge.net, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, Jia-Ju Bai <baijiaju1990@gmail.com>
Subject: [PATCH] atm: atmtcp: Replace GFP_ATOMIC with GFP_KERNEL in atmtcp_v_send
Date:   Fri, 26 Jan 2018 11:52:59 +0800
Message-Id: <1516938779-27562-1-git-send-email-baijiaju1990@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

After checking all possible call chains to atmtcp_v_send() here,
my tool finds that atmtcp_v_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 atmtcp_v_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@gmail.com>
---
 drivers/atm/atmtcp.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/atm/atmtcp.c b/drivers/atm/atmtcp.c
index afebeb1c..f7a27ed 100644
--- a/drivers/atm/atmtcp.c
+++ b/drivers/atm/atmtcp.c
@@ -210,7 +210,7 @@ static int atmtcp_v_send(struct atm_vcc *vcc,struct sk_buff *skb)
 		return -ENOLINK;
 	}
 	size = skb->len+sizeof(struct atmtcp_hdr);
-	new_skb = atm_alloc_charge(out_vcc,size,GFP_ATOMIC);
+	new_skb = atm_alloc_charge(out_vcc,size,GFP_KERNEL);
 	if (!new_skb) {
 		if (vcc->pop) vcc->pop(vcc,skb);
 		else dev_kfree_skb(skb);
-- 
1.7.9.5