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

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Message-ID: <alpine.LFD.2.02.1203062101040.2742@ionos>
Date:	Tue, 6 Mar 2012 21:26:07 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Sven Joachim <svenjoac@....de>
cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Stefan Lippers-Hollmann <s.L-H@....de>,
	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

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
>   1:        101    XT-PIC-XT-PIC    i8042
>   2:          0    XT-PIC-XT-PIC    cascade
>   3:          1    XT-PIC-XT-PIC  
>   4:          1    XT-PIC-XT-PIC  
>   5:          0    XT-PIC-XT-PIC    ehci_hcd:usb1, uhci_hcd:usb2
>   6:          1    XT-PIC-XT-PIC    i915, uhci_hcd:usb5, yenta
>   7:          1    XT-PIC-XT-PIC  
>   8:          0    XT-PIC-XT-PIC    rtc0
>   9:        634    XT-PIC-XT-PIC    acpi
>  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.

Reported-by: Sven Joachim <svenjoac@....de>
Cc: stable@...r.kernel.org
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---

Index: linux-2.6/kernel/irq/manage.c
===================================================================
--- linux-2.6.orig/kernel/irq/manage.c
+++ linux-2.6/kernel/irq/manage.c
@@ -996,11 +996,13 @@ __setup_irq(unsigned int irq, struct irq
 	 * Setup the thread mask for this irqaction. Unlikely to have
 	 * 32 resp 64 irqs sharing one line, but who knows.
 	 */
-	if (new->flags & IRQF_ONESHOT && thread_mask == ~0UL) {
-		ret = -EBUSY;
-		goto out_mask;
+	if (new->flags & IRQF_ONESHOT) {
+		if (thread_mask == ~0UL) {
+			ret = -EBUSY;
+			goto out_mask;
+		}
+		new->thread_mask = new->flags & IRQF_ONESHOT;
 	}
-	new->thread_mask = 1 << ffz(thread_mask);
 
 	if (!shared) {
 		init_waitqueue_head(&desc->wait_for_threads);
--
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