Re: [-next] !irqd_can_balance() WARNINGs at irq_move_masked_irq()

From: Thomas Gleixner
Date: Sun Jun 21 2015 - 10:38:14 EST


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@xxxxxxxxxxxxx>
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@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
---
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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