netdev - [PATCH AUTOSEL 3.18 5/6] net: faraday: ftmac100: remove netif_running(netdev) check before disabling interrupts

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Date:   Thu, 29 Nov 2018 01:05:34 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     stable@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Vincent Chen <vincentc@...estech.com>,
        "David S . Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 3.18 5/6] net: faraday: ftmac100: remove netif_running(netdev) check before disabling interrupts

From: Vincent Chen <vincentc@...estech.com>

[ Upstream commit 426a593e641ebf0d9288f0a2fcab644a86820220 ]

In the original ftmac100_interrupt(), the interrupts are only disabled when
the condition "netif_running(netdev)" is true. However, this condition
causes kerenl hang in the following case. When the user requests to
disable the network device, kernel will clear the bit __LINK_STATE_START
from the dev->state and then call the driver's ndo_stop function. Network
device interrupts are not blocked during this process. If an interrupt
occurs between clearing __LINK_STATE_START and stopping network device,
kernel cannot disable the interrupts due to the condition
"netif_running(netdev)" in the ISR. Hence, kernel will hang due to the
continuous interruption of the network device.

In order to solve the above problem, the interrupts of the network device
should always be disabled in the ISR without being restricted by the
condition "netif_running(netdev)".

[V2]
Remove unnecessary curly braces.

Signed-off-by: Vincent Chen <vincentc@...estech.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/ethernet/faraday/ftmac100.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/faraday/ftmac100.c b/drivers/net/ethernet/faraday/ftmac100.c
index 4ff1adc6bfca..9a0703f2da9a 100644
--- a/drivers/net/ethernet/faraday/ftmac100.c
+++ b/drivers/net/ethernet/faraday/ftmac100.c
@@ -865,11 +865,10 @@ static irqreturn_t ftmac100_interrupt(int irq, void *dev_id)
 	struct net_device *netdev = dev_id;
 	struct ftmac100 *priv = netdev_priv(netdev);

-	if (likely(netif_running(netdev))) {
-		/* Disable interrupts for polling */
-		ftmac100_disable_all_int(priv);
+	/* Disable interrupts for polling */
+	ftmac100_disable_all_int(priv);
+	if (likely(netif_running(netdev)))
 		napi_schedule(&priv->napi);
-	}

 	return IRQ_HANDLED;
 }
-- 
2.17.1