linux-kernel - Re: [PATCH] net: eepro testing positive EBUSY return by request

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Date:	Fri, 31 Dec 2010 15:27:42 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	roel kluin <roel.kluin@...il.com>
Cc:	davem@...emloft.net, netdev@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net: eepro testing positive EBUSY return by
 request_irq()?

On Fri, 2010-12-31 at 15:47 +0100, roel kluin wrote:
> Fix -EBUSY test for request_irq().
> 
> Signed-off-by: Roel Kluin <roel.kluin@...il.com>
> ---
>  drivers/net/eepro.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> I just found this in the code, no bug was observed. Is this patch needed? the test
> for an -EBUSY return by request_irq() occurs much more frequently in kernel code.
> 
> diff --git a/drivers/net/eepro.c b/drivers/net/eepro.c
> index 7c82631..47cfecb 100644
> --- a/drivers/net/eepro.c
> +++ b/drivers/net/eepro.c
> @@ -920,7 +920,7 @@ static int	eepro_grab_irq(struct net_device *dev)
>  
>  		eepro_sw2bank0(ioaddr); /* Switch back to Bank 0 */
>  
> -		if (request_irq (*irqp, NULL, IRQF_SHARED, "bogus", dev) != EBUSY) {
> +		if (request_irq (*irqp, NULL, IRQF_SHARED, "bogus", dev) != -EBUSY) {
>  			unsigned long irq_mask;
>  			/* Twinkle the interrupt, and check if it's seen */
>  			irq_mask = probe_irq_on();

This condition is completely bogus - request_irq() with a NULL handler
now returns -EINVAL before even checking whether the IRQ is in use.  The
code should be fixed along the lines of what I did for 3c503 in commit
b0cf4dfb7cd21556efd9a6a67edcba0840b4d98d.

The e2100 and hp net drivers have the same bug.

Ben.

-- 
Ben Hutchings
Once a job is fouled up, anything done to improve it makes it worse.

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