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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jia-Ju Bai <baijiaju1990@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.18 055/168] net: cadence: Fix a sleep-in-atomic-context bug in macb_halt_tx()
Date:   Mon,  8 Oct 2018 20:30:35 +0200
Message-Id: <20181008175622.143089820@linuxfoundation.org>
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4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/cadence/macb_main.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -648,7 +648,7 @@ 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;