linux-kernel - [PATCH] net: socionext: Fix two sleep-in-atomic-context bugs in ave_rxfifo

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Message-Id: <20180915040246.22703-1-baijiaju1990@gmail.com>
Date:   Sat, 15 Sep 2018 12:02:46 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     davem@...emloft.net, hayashi.kunihiko@...ionext.com,
        yamada.masahiro@...ionext.com, robh@...nel.org, andrew@...n.ch
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH] net: socionext: Fix two sleep-in-atomic-context bugs in ave_rxfifo_reset()

The driver may sleep with holding a spinlock.
The function call paths (from bottom to top) in Linux-4.17 are:

[FUNC] usleep_range
drivers/net/ethernet/socionext/sni_ave.c, 892: 
	usleep_range in ave_rxfifo_reset
drivers/net/ethernet/socionext/sni_ave.c, 932: 
	ave_rxfifo_reset in ave_irq_handler

[FUNC] usleep_range
drivers/net/ethernet/socionext/sni_ave.c, 888: 
	usleep_range in ave_rxfifo_reset
drivers/net/ethernet/socionext/sni_ave.c, 932: 
	ave_rxfifo_reset in ave_irq_handler

To fix these bugs, usleep_range() is replaced with udelay().

These bugs are found by my static analysis tool DSAC.

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
 drivers/net/ethernet/socionext/sni_ave.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/socionext/sni_ave.c b/drivers/net/ethernet/socionext/sni_ave.c
index f7ecceeb1e28..3c784a29ce0d 100644
--- a/drivers/net/ethernet/socionext/sni_ave.c
+++ b/drivers/net/ethernet/socionext/sni_ave.c
@@ -904,11 +904,11 @@ static void ave_rxfifo_reset(struct net_device *ndev)
 
 	/* assert reset */
 	writel(AVE_GRR_RXFFR, priv->base + AVE_GRR);
-	usleep_range(40, 50);
+	udelay(50);
 
 	/* negate reset */
 	writel(0, priv->base + AVE_GRR);
-	usleep_range(10, 20);
+	udelay(20);
 
 	/* negate interrupt status */
 	writel(AVE_GI_RXOVF, priv->base + AVE_GISR);
-- 
2.17.0