From: Thomas Gleixner <tglx@linutronix.de>
To: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
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>,
x86@kernel.org, Len Brown <len.brown@intel.com>,
Pavel Machek <pavel@ucw.cz>, Prarit Bhargava <prarit@redhat.com>,
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>,
linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
linux-acpi@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
linux-pm@vger.kernel.org
Subject: Re: [Patch v4 14/16] x86, irq: Introduce helper to check whether an IOAPIC has been registered
Date: Wed, 10 Sep 2014 22:08:00 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.10.1409102206300.4178@nanos> (raw)
In-Reply-To: <540FBB93.4020509@linux.intel.com>
On Wed, 10 Sep 2014, Jiang Liu wrote:
> On 2014/9/9 20:37, Thomas Gleixner wrote:
> >> + ret = mp_ioapic_registered(gsi_base);
> >> + up_write(&acpi_ioapic_rwsem);
> >> +
> >> + return ret;
> >> +}
> >
> > So I assume that this is for a particular caller in the apci ioapic
> > hotplug code and that call site has its own serialization. Otherwise
> > the return value is not protected at all.
> >
> > Please add a Docbook comment to that function, and document the
> > locking rules as thats pretty non obvious.
> How about this comments about locking rules?
> /*
> * Locks related to IOAPIC hotplug
> * Hotplug side:
> * ->lock_device_hotplug() //device_hotplug_lock
> * ->acpi_ioapic_rwsem
> * ->ioapic_lock
> * Interrupt mapping side:
> * ->acpi_ioapic_rwsem
> * ->ioapic_mutex
> * ->ioapic_lock
> */
That looks asymetric. Why is the hotplug side not taking ioapic_mutex?
Thanks,
tglx
next prev parent reply other threads:[~2014-09-10 20:08 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-28 2:22 [Patch v4 00/16] Enable support of IOAPIC hotplug on x86 platforms Jiang Liu
2014-08-28 2:22 ` [Patch v4 01/16] x86, PCI, ACPI: Kill private function resource_to_addr() in arch/x86/pci/acpi.c Jiang Liu
2014-08-28 2:22 ` [Patch v4 02/16] ACPI: Correct return value of acpi_dev_resource_address_space() Jiang Liu
2014-08-28 2:22 ` [Patch v4 03/16] ACPI: Fix minor syntax issues in processor_core.c Jiang Liu
2014-08-28 2:22 ` [Patch v4 04/16] ACPI: Rename processor_core.c as apic_id.c Jiang Liu
2014-09-07 22:37 ` Rafael J. Wysocki
2014-09-08 12:51 ` Hanjun Guo
2014-09-08 21:00 ` Rafael J. Wysocki
2014-09-09 2:33 ` Jiang Liu
2014-08-28 2:22 ` [Patch v4 05/16] ACPI: Add interfaces to parse IOAPIC ID for IOAPIC hotplug Jiang Liu
2014-09-09 10:54 ` Thomas Gleixner
2014-09-10 1:58 ` Jiang Liu
2014-08-28 2:22 ` [Patch v4 06/16] x86, irq: Split out alloc_ioapic_save_registers() Jiang Liu
2014-08-28 2:22 ` [Patch v4 07/16] x86, irq: Prefer assigned ID in APIC ID register for x86_64 Jiang Liu
2014-09-09 11:04 ` Thomas Gleixner
2014-09-10 2:14 ` Jiang Liu
2014-08-28 2:22 ` [Patch v4 08/16] x86, irq: Remove __init marker for functions will be used by IOAPIC hotplug Jiang Liu
2014-08-28 2:22 ` [Patch v4 09/16] x86, irq: Keep balance of IOAPIC pin reference count Jiang Liu
2014-08-28 2:22 ` [Patch v4 10/16] x86, irq: Refine mp_register_ioapic() to prepare for IOAPIC hotplug Jiang Liu
2014-08-28 2:22 ` [Patch v4 11/16] x86, irq, ACPI: Introduce a rwsem to protect IOAPIC operations from hotplug Jiang Liu
2014-08-28 2:22 ` [Patch v4 12/16] x86, irq, ACPI: Implement interface to support ACPI based IOAPIC hot-addition Jiang Liu
2014-09-09 12:20 ` Thomas Gleixner
2014-09-10 3:13 ` Jiang Liu
2014-09-10 20:06 ` Thomas Gleixner
2014-09-11 6:05 ` Jiang Liu
2014-09-11 6:08 ` Jiang Liu
2014-08-28 2:22 ` [Patch v4 13/16] x86, irq, ACPI: Implement interfaces to support ACPI based IOAPIC hot-removal Jiang Liu
2014-08-28 2:22 ` [Patch v4 14/16] x86, irq: Introduce helper to check whether an IOAPIC has been registered Jiang Liu
2014-09-09 12:37 ` Thomas Gleixner
2014-09-10 2:46 ` Jiang Liu
2014-09-10 20:08 ` Thomas Gleixner [this message]
2014-09-11 7:17 ` Jiang Liu
2014-08-28 2:22 ` [Patch v4 15/16] PCI: Remove PCI ioapic driver Jiang Liu
2014-08-28 2:22 ` [Patch v4 16/16] x86, irq, ACPI: Implement ACPI driver to support IOAPIC hotplug Jiang Liu
2014-09-07 22:05 ` [Patch v4 00/16] Enable support of IOAPIC hotplug on x86 platforms Rafael J. Wysocki
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