linux-kernel - Re: [-next] !irqd_can_balance() WARNINGs at irq_move_masked

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Date:	Sun, 21 Jun 2015 16:37:46 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
cc:	Jiang Liu <jiang.liu@...ux.intel.com>,
	Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [-next] !irqd_can_balance() WARNINGs at irq_move_masked_irq()

On Sun, 21 Jun 2015, Sergey Senozhatsky wrote:
> On (06/20/15 11:12), Thomas Gleixner wrote:
> > One last request. Can you please provide /proc/timer_list and dmesg
> > from a mainline kernel for comparison?
> 
> attached.

Thanks for providing that. As I feared already, there is a regression
as well. The new code fails to allocated more than one hpet MSI
interrupt. Fix below.

Thanks,

	tglx
---
Subject: x86/hpet: Use proper hpet device number for MSI allocation
From: Thomas Gleixner <tglx@...utronix.de>
Date: Sun, 21 Jun 2015 16:21:50 +0200

hpet_assign_irq() is called with hpet_device->num as "hardware
interrupt number", but hpet_device->num is initialized after the
interrupt has been assigned, so it's always 0. As a consequence only
the first MSI allocation succeeds, the following ones fail because the
"hardware interrupt number" already exists.

Move the initialization of dev->num and other fields before the call
to hpet_assign_irq(), which is the ordering before the offending
commit which introduced that regression.

Fixes: "3cb96f0c9733 x86/hpet: Enhance HPET IRQ to support hierarchical irqdomains"
Reported-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Jiang Liu <jiang.liu@...ux.intel.com>
Cc: Borislav Petkov <bp@...en8.de>
---
 arch/x86/kernel/hpet.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

Index: tip/arch/x86/kernel/hpet.c
===================================================================
--- tip.orig/arch/x86/kernel/hpet.c
+++ tip/arch/x86/kernel/hpet.c
@@ -577,16 +577,17 @@ static void hpet_msi_capability_lookup(u
 		if (!(cfg & HPET_TN_FSB_CAP))
 			continue;
 
+		hdev->flags = 0;
+		if (cfg & HPET_TN_PERIODIC_CAP)
+			hdev->flags |= HPET_DEV_PERI_CAP;
+		sprintf(hdev->name, "hpet%d", i);
+		hdev->num = i;
+
 		irq = hpet_assign_irq(hpet_domain, hdev, hdev->num);
 		if (irq <= 0)
 			continue;
 
-		sprintf(hdev->name, "hpet%d", i);
-		hdev->num = i;
 		hdev->irq = irq;
-		hdev->flags = 0;
-		if (cfg & HPET_TN_PERIODIC_CAP)
-			hdev->flags |= HPET_DEV_PERI_CAP;
 		hdev->flags |= HPET_DEV_FSB_CAP;
 		hdev->flags |= HPET_DEV_VALID;
 		num_timers_used++;
--
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