Re: [Patch v4] x86, irq, PCI: Keep IRQ assignment for runtime power management

From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Jiang Liu <jiang.liu@linux.intel.com>,
	EmanueL Czirai <amanual@openmailbox.org>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	Yinghai Lu <yinghai@kernel.org>, Borislav Petkov <bp@alien8.de>,
	Grant Likely <grant.likely@linaro.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Tony Luck <tony.luck@intel.com>, Joerg Roedel <joro@8bytes.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	x86@kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux PCI <linux-pci@vger.kernel.org>,
	ACPI Devel Maling List <linux-acpi@vger.kernel.org>
Subject: Re: [Patch v4] x86, irq, PCI: Keep IRQ assignment for runtime power management
Date: Sat, 30 Aug 2014 01:24:53 +0200	[thread overview]
Message-ID: <8823237.zCdVqYrZ5W@vostro.rjw.lan> (raw)
In-Reply-To: <CAJZ5v0ikimRs4XJihULUdS-ZtU=xBMJECbKmzpUf1ZnzXijihQ@mail.gmail.com>

On Friday, August 29, 2014 04:42:34 PM Rafael J. Wysocki wrote:
> On Fri, Aug 29, 2014 at 11:26 AM, Jiang Liu <jiang.liu@linux.intel.com> wrote:
> > Now IOAPIC driver dynamically allocates IRQ numbers for IOAPIC pins.
> > We need to keep IRQ assignment for PCI devices during runtime power
> > management, otherwise it may cause failure of device wakeups.
> >
> > Commit 3eec595235c17a7 "x86, irq, PCI: Keep IRQ assignment for PCI
> > devices during suspend/hibernation" has fixed the issue for suspend/
> > hibernation, we also need the same fix for runtime device sleep too.
> >
> > Fix: https://bugzilla.kernel.org/show_bug.cgi?id=83271
> > Reported-and-Tested-by: EmanueL Czirai <amanual@openmailbox.org>
> > Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
> > ---
> >  arch/x86/include/asm/io_apic.h |    2 ++
> >  arch/x86/kernel/apic/io_apic.c |   12 ++++++++++++
> >  arch/x86/pci/intel_mid_pci.c   |    2 +-
> >  arch/x86/pci/irq.c             |    2 +-
> >  drivers/acpi/pci_irq.c         |    4 ++++
> >  5 files changed, 20 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/io_apic.h b/arch/x86/include/asm/io_apic.h
> > index 0aeed5ca356e..478c490f3654 100644
> > --- a/arch/x86/include/asm/io_apic.h
> > +++ b/arch/x86/include/asm/io_apic.h
> > @@ -227,6 +227,8 @@ static inline void io_apic_modify(unsigned int apic, unsigned int reg, unsigned
> >
> >  extern void io_apic_eoi(unsigned int apic, unsigned int vector);
> >
> > +extern bool mp_should_keep_irq(struct device *dev);
> > +
> >  #else  /* !CONFIG_X86_IO_APIC */
> >
> >  #define io_apic_assign_pci_irqs 0
> > diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
> > index 29290f554e79..1e9a921d9701 100644
> > --- a/arch/x86/kernel/apic/io_apic.c
> > +++ b/arch/x86/kernel/apic/io_apic.c
> > @@ -3946,6 +3946,18 @@ int mp_set_gsi_attr(u32 gsi, int trigger, int polarity, int node)
> >         return ret;
> >  }
> >
> > +bool mp_should_keep_irq(struct device *dev)
> > +{
> > +       if (dev->power.is_prepared)
> > +               return true;
> > +#ifdef CONFIG_PM_RUNTIME
> > +       if (dev->power.runtime_status == RPM_SUSPENDING)
> > +               return true;
> > +#endif
> 
> No, you can't do that.  It is racy and incorrect.

Well, maybe not.

> Please give me some time for looking into this.

So I guess the intended check is "Am I running in a suspend callback"?

Rafael