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Commit d2779e99 authored by Sergei Shtylyov's avatar Sergei Shtylyov Committed by David S. Miller
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sh_eth: fix napi_{en|dis}able() calls racing against interrupts 



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: default avatarSergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3a1c7565

drivers/net/ethernet/renesas/sh_eth.c

+7 −5
Original line number Diff line number Diff line
@@ -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);