[PATCH v2] net: faraday: ftmac100: remove netif_running(netdev) check before disabling interrupts

[PATCH v2] net: faraday: ftmac100: remove netif_running(netdev) check before disabling interrupts

[Vincent Chen]

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@andestech.com>
---
 drivers/net/ethernet/faraday/ftmac100.c |    7 +++----
 1 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/faraday/ftmac100.c b/drivers/net/ethernet/faraday/ftmac100.c
index 21d7660..17a3625 100644
--- a/drivers/net/ethernet/faraday/ftmac100.c
+++ b/drivers/net/ethernet/faraday/ftmac100.c
@@ -875,11 +875,10 @@ 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;
 }
-- 
1.7.1

Re: [PATCH v2] net: faraday: ftmac100: remove netif_running(netdev) check before disabling interrupts

[David Miller]

From: Vincent Chen <vincentc@andestech.com>
Date: Wed, 21 Nov 2018 09:38:11 +0800

> 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@andestech.com>

Applied.