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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: solos-pci: Replace GFP_ATOMIC with GFP_KERNEL in psend
Date:   Fri, 26 Jan 2018 11:49:30 +0800
Message-Id: <1516938570-27453-1-git-send-email-baijiaju1990@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

After checking all possible call chains to psend() here,
my tool finds that psend() 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 psend() 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/solos-pci.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/atm/solos-pci.c b/drivers/atm/solos-pci.c
index 0df1a1c..ac10b62 100644
--- a/drivers/atm/solos-pci.c
+++ b/drivers/atm/solos-pci.c
@@ -1166,7 +1166,7 @@ static int psend(struct atm_vcc *vcc, struct sk_buff *skb)
 		if (skb_headroom(skb) < sizeof(*header))
 			expand_by = sizeof(*header) - skb_headroom(skb);
 
-		ret = pskb_expand_head(skb, expand_by, 0, GFP_ATOMIC);
+		ret = pskb_expand_head(skb, expand_by, 0, GFP_KERNEL);
 		if (ret) {
 			dev_warn(&card->dev->dev, "pskb_expand_head failed.\n");
 			solos_pop(vcc, skb);
-- 
1.7.9.5