linux-kernel - Re: [ 57/72] genirq: Unmask oneshot irqs when thread was not woken

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Date:	Tue, 6 Mar 2012 22:08:40 +0100
From:	"Stefan Lippers-Hollmann" <s.L-H@....de>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Sven Joachim <svenjoac@....de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Greg KH <gregkh@...uxfoundation.org>,
	LKML <linux-kernel@...r.kernel.org>, stable@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Jonathan Nieder <jrnieder@...il.com>,
	linux-wireless@...r.kernel.org,
	Stefano Brivio <stefano.brivio@...imi.it>
Subject: Re: [ 57/72] genirq: Unmask oneshot irqs when thread was not woken

Hi

On Tuesday 06 March 2012, Thomas Gleixner wrote:
> On Tue, 6 Mar 2012, Sven Joachim wrote:
> > Am 06.03.2012 um 20:31 schrieb Thomas Gleixner:
> > 
> > > Stephan, Sven: Can you please provide the output of /proc/interrupts ?
> > 
> > Here is mine, from a freshly booted 3.3-rc6 kernel.
> > 
> > Cheers,
> >        Sven
> > 
> >            CPU0       
> >   0:      25050    XT-PIC-XT-PIC    timer
[…]
> >  10:        341    XT-PIC-XT-PIC    uhci_hcd:usb4, snd_hda_intel, b43
> 
> Ah, XT-PIC uses handle_level_irq(). /me bangs head against desk.
> 
> Does the patch below fix the problem for you ?
> 
> Thanks,
> 
> 	tglx
> 
> ----------------->
> Subject: genirq: Clear action->thread_mask if IRQ_ONESHOT is not set
> 
> commit ac5637611(genirq: Unmask oneshot irqs when thread was not
> woken) fails to unmask when a !IRQ_ONESHOT threaded handler is handled
> by handle_level_irq. This happens because thread_mask is or'ed
> unconditionally in irq_wake_thread(), but for !IRQ_ONESHOT interrupts
> never cleared. So the check for !desc->thread_active fails and keeps
> the interrupt disabled.
> 
> Keep the thread_mask zero for !IRQ_ONESHOT interrupts.
[…]

I can confirm that this patch, applied to 2.6.9, including "genirq: 
Unmask oneshot irqs when thread was not woken", and + the current 
stable queue-3.2 fixes b43 wlan operations. Feel free to add 
Tested-by: Stefan Lippers-Hollmann <s.l-h@....de>
if you like.

Thanks a lot
	Stefan Lippers-Hollmann


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