From: Ben Hutchings <ben@decadent.org.uk>
To: roel kluin <roel.kluin@gmail.com>
Cc: davem@davemloft.net, netdev@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>
In-Reply-To: <4D1DECFC.8020701@gmail.com>
References: <4D1DECFC.8020701@gmail.com>
Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-jYbOy25JKJQuq2mVCUlZ"
Date: Fri, 31 Dec 2010 15:27:42 +0000
Message-ID: <1293809262.2870.45.camel@localhost>
Mime-Version: 1.0
Subject: Re: [PATCH] net: eepro testing positive EBUSY return by
 request_irq()?
Sender: linux-kernel-owner@vger.kernel.org
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On Fri, 2010-12-31 at 15:47 +0100, roel kluin wrote:
> Fix -EBUSY test for request_irq().
>=20
> Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
> ---
>  drivers/net/eepro.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
>=20
> 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 kern=
el code.
>=20
> 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)
> =20
>  		eepro_sw2bank0(ioaddr); /* Switch back to Bank 0 */
> =20
> -		if (request_irq (*irqp, NULL, IRQF_SHARED, "bogus", dev) !=3D EBUSY) {
> +		if (request_irq (*irqp, NULL, IRQF_SHARED, "bogus", dev) !=3D -EBUSY) =
{
>  			unsigned long irq_mask;
>  			/* Twinkle the interrupt, and check if it's seen */
>  			irq_mask =3D 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.

--=20
Ben Hutchings
Once a job is fouled up, anything done to improve it makes it worse.

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