netdev - Re: b44: regression in 2.6.22 (resend)

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Message-ID: <1180448075.17146.12.camel@dhcp-10-12-136-115.broadcom.com>
Date:	Tue, 29 May 2007 07:14:35 -0700
From:	"Gary Zambrano" <zambrano@...adcom.com>
To:	"Michael Buesch" <mb@...sch.de>
cc:	"Maximilian Engelhardt" <maxi@...monizer.de>,
	"linux-kernel" <linux-kernel@...r.kernel.org>,
	"linux-wireless" <linux-wireless@...r.kernel.org>,
	"Stephen Hemminger" <shemminger@...ux-foundation.org>,
	"Arnaldo Carvalho de Melo" <acme@...stprotocols.net>,
	"Jeff Garzik" <jgarzik@...ox.com>, netdev@...r.kernel.org,
	"Andrew Morton" <akpm@...ux-foundation.org>
Subject: Re: b44: regression in 2.6.22 (resend)

On Mon, 2007-05-28 at 16:55 +0200, Michael Buesch wrote:
> On Monday 28 May 2007 16:12:12 Maximilian Engelhardt wrote:
> > On Monday 28 May 2007, Michael Buesch wrote:
> > > Can you also test the following patch?
> > > I think there's a bug in b44 that is doesn't properly discard
> > > shared IRQs, so it might possibly generate a NAPI storm, dunno.
> > > Worth a try.
> > >
> > > Index: linux-2.6.22-rc3/drivers/net/b44.c
> > > ===================================================================
> > > --- linux-2.6.22-rc3.orig/drivers/net/b44.c	2007-05-27 23:01:44.000000000
> > > +0200 +++ linux-2.6.22-rc3/drivers/net/b44.c	2007-05-28 12:48:27.000000000
> > > +0200 @@ -911,6 +911,8 @@ static irqreturn_t b44_interrupt(int irq
> > >  	spin_lock(&bp->lock);
> > >
> > >  	istat = br32(bp, B44_ISTAT);
> > > +	if (istat == 0xFFFFFFFF)
> > > +		goto out; /* Shared IRQ not for us */
> > >  	imask = br32(bp, B44_IMASK);
> > >
> > >  	/* The interrupt mask register controls which interrupt bits
> > > @@ -942,6 +944,7 @@ irq_ack:
> > >  		bw32(bp, B44_ISTAT, istat);
> > >  		br32(bp, B44_ISTAT);
> > >  	}
> > > +out:
> > >  	spin_unlock(&bp->lock);
> > >  	return IRQ_RETVAL(handled);
> > >  }
> > 
> > I did try this patch on a affected kernel, but I didn't notice any big 
> > difference. Perhaps the kernel is a bit less slow during the test, but It's 
> > hard to tell.
> 
> Ok, but anyway. I think this is a bug and needs to be fixed this way. Gary?
> 

Thanks Michael.
No, I don't think this is a bug and it does not need to be fixed.
Thanks,
Gary


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