2018-11-20 06:12:17

by Vincent Chen

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

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)".

Signed-off-by: Vincent Chen <[email protected]>
---
drivers/net/ethernet/faraday/ftmac100.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/faraday/ftmac100.c b/drivers/net/ethernet/faraday/ftmac100.c
index 21d7660..22dcf4c 100644
--- a/drivers/net/ethernet/faraday/ftmac100.c
+++ b/drivers/net/ethernet/faraday/ftmac100.c
@@ -875,9 +875,9 @@ static irqreturn_t ftmac100_interrupt(int irq, void *dev_id)
struct net_device *netdev = dev_id;
struct ftmac100 *priv = netdev_priv(netdev);

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

--
1.7.1

2018-11-20 18:29:38

by David Miller

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

aFrom: Vincent Chen <[email protected]>
Date: Tue, 20 Nov 2018 13:37:46 +0800

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

This is now a single-line basic block, so please remove the curly
braces.

Thank you.

2018-11-21 01:48:07

by Vincent Chen

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

On Wed, Nov 21, 2018 at 02:28:43AM +0800, David Miller wrote:
> aFrom: Vincent Chen <[email protected]>
> Date: Tue, 20 Nov 2018 13:37:46 +0800
>
> > + /* Disable interrupts for polling */
> > + ftmac100_disable_all_int(priv);
> > if (likely(netif_running(netdev))) {
> > - /* Disable interrupts for polling */
> > - ftmac100_disable_all_int(priv);
> > napi_schedule(&priv->napi);
> > }
>
> This is now a single-line basic block, so please remove the curly
> braces.
>
> Thank you.

OK. I will remove it.
Thank you.