[PATCH AUTOSEL 4.9 15/23] net: cadence: Fix a sleep-in-atomic-context bug in macb_halt_tx()

From: Sasha Levin <Alexander.Levin@microsoft.com>
To: "stable@vger.kernel.org" <stable@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: Jia-Ju Bai <baijiaju1990@gmail.com>,
	"David S . Miller" <davem@davemloft.net>,
	Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL 4.9 15/23] net: cadence: Fix a sleep-in-atomic-context bug in macb_halt_tx()
Date: Mon, 24 Sep 2018 14:49:32 +0000	[thread overview]
Message-ID: <20180924144919.164617-15-alexander.levin@microsoft.com> (raw)
In-Reply-To: <20180924144919.164617-1-alexander.levin@microsoft.com>

From: Jia-Ju Bai <baijiaju1990@gmail.com>

[ Upstream commit 16fe10cf92783ed9ceb182d6ea2b8adf5e8ec1b8 ]

The kernel module may sleep with holding a spinlock.

The function call paths (from bottom to top) in Linux-4.16 are:

[FUNC] usleep_range
drivers/net/ethernet/cadence/macb_main.c, 648:
	usleep_range in macb_halt_tx
drivers/net/ethernet/cadence/macb_main.c, 730:
	macb_halt_tx in macb_tx_error_task
drivers/net/ethernet/cadence/macb_main.c, 721:
	_raw_spin_lock_irqsave in macb_tx_error_task

To fix this bug, usleep_range() is replaced with udelay().

This bug is found by my static analysis tool DSAC.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 drivers/net/ethernet/cadence/macb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index ec09fcece711..2e1585635083 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -517,7 +517,7 @@ static int macb_halt_tx(struct macb *bp)
 		if (!(status & MACB_BIT(TGO)))
 			return 0;
 
-		usleep_range(10, 250);
+		udelay(250);
 	} while (time_before(halt_time, timeout));
 
 	return -ETIMEDOUT;
-- 
2.17.1
