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sh_eth: fix napi_{en|dis}able() calls racing against interrupts

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While implementing NAPI for the driver, I overlooked the race conditions where
interrupt  handler might have called napi_schedule_prep() before napi_enable()
was called or after napi_disable() was called. If RX interrupt happens, this
would cause the endless interrupts and messages like:

sh-eth eth0: ignoring interrupt, status 0x00040000, mask 0x01ff009f.

The interrupt wouldn't even be masked by the kernel eventually since the handler
would return IRQ_HANDLED all the time.

As a fix, move napi_enable() call before request_irq() call and napi_disable()
call after free_irq() call.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Sergei Shtylyov 2013-09-04 02:41:27 +04:00 committed by David S. Miller
parent 3a1c756590
commit d2779e9946
1 changed files with 7 additions and 5 deletions
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12
drivers/net/ethernet/renesas/sh_eth.c
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@ -1857,11 +1857,13 @@ static int sh_eth_open(struct net_device *ndev)
pm_runtime_get_sync(&mdp->pdev->dev);
napi_enable(&mdp->napi);
ret = request_irq(ndev->irq, sh_eth_interrupt,
mdp->cd->irq_flags, ndev->name, ndev);
if (ret) {
dev_err(&ndev->dev, "Can not assign IRQ number\n");
return ret;
goto out_napi_off;
}
/* Descriptor set */
@ -1879,12 +1881,12 @@ static int sh_eth_open(struct net_device *ndev)
if (ret)
goto out_free_irq;
napi_enable(&mdp->napi);
return ret;
out_free_irq:
free_irq(ndev->irq, ndev);
out_napi_off:
napi_disable(&mdp->napi);
pm_runtime_put_sync(&mdp->pdev->dev);
return ret;
}
@ -1976,8 +1978,6 @@ static int sh_eth_close(struct net_device *ndev)
{
struct sh_eth_private *mdp = netdev_priv(ndev);
napi_disable(&mdp->napi);
netif_stop_queue(ndev);
/* Disable interrupts by clearing the interrupt mask. */
@ -1995,6 +1995,8 @@ static int sh_eth_close(struct net_device *ndev)
free_irq(ndev->irq, ndev);
napi_disable(&mdp->napi);
/* Free all the skbuffs in the Rx queue. */
sh_eth_ring_free(ndev);