From: Jiang Liu <jiang.liu@linux.intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
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>,
Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>,
x86@kernel.org, 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 12/16] x86, irq, ACPI: Implement interface to support ACPI based IOAPIC hot-addition
Date: Thu, 11 Sep 2014 14:08:32 +0800 [thread overview]
Message-ID: <54113C60.2080501@linux.intel.com> (raw)
In-Reply-To: <alpine.DEB.2.10.1409102202530.4178@nanos>
On 2014/9/11 4:06, Thomas Gleixner wrote:
> On Wed, 10 Sep 2014, Jiang Liu wrote:
>>>> int mp_register_ioapic(int id, u32 address, u32 gsi_base,
>>>> @@ -3867,8 +3873,15 @@ int mp_register_ioapic(int id, u32 address, u32 gsi_base,
>>>> }
>>>> for_each_ioapic(ioapic)
>>>> if (ioapics[ioapic].mp_config.apicaddr == address) {
>>>> - pr_warn("address 0x%x conflicts with IOAPIC%d\n",
>>>> - address, ioapic);
>>>> + /*
>>>> + * IOAPIC unit may also be visible in PCI scope.
>>>> + * When ioapic PCI driver's probe() is called,
>>>> + * the IOAPIC unit may have already been initialized
>>>> + * at boot time.
>>>> + */
>>>> + if (!ioapic_initialized)
>>>> + pr_warn("address 0x%x conflicts with IOAPIC%d\n",
>>>> + address, ioapic);
>>>
>>> Hmm. This smells fishy. Why do we allow multiple initializations of
>>> the same IOAPIC in the first place. Either it's done via ACPI or via
>>> PCI, but not both.
>> The ACPI subsystem will register and initialize all IOAPICs when walking
>> ACPI MADT table during boot, before initializing PCI subsystem.
>> Later when binding ioapic PCI driver to IOAPIC PCI device, it will try
>> to register the IOAPIC device again.
>>
>> After this patchset is applied, we could remove the !ioapic_initialized
>> check. We check acpi_ioapic_register() before calling
>> acpi_register_ioapic(). So the check becomes redundant.
>> Or we could remove the temporary code from this patch.
>
> How about removing the disfunctional ioapic PCI driver first and then
> implementing the whole thing cleanly?
>
>>>
>>>> return -EEXIST;
>>>> }
>>>>
>>>> @@ -3918,6 +3931,14 @@ int mp_register_ioapic(int id, u32 address, u32 gsi_base,
>>>> ioapics[idx].irqdomain = NULL;
>>>> ioapics[idx].irqdomain_cfg = *cfg;
>>>>
>>>> + if (ioapic_initialized) {
>>>
>>> I have a hard time to understand this conditional. Why can't we do
>>> that unconditionally?
>> How about following comments?
>> /*
>> * If mp_register_ioapic() is called during early boot stage when
>> * walking ACPI/SFI/DT tables, it's too early to create irqdomain,
>> * we are still using bootmem allocator. So delay it to setup_IO_APIC().
>> */
>
> Fine, but then the "if (ioapic_initialized)" conditional still does
> not make sense. We surely have some global non ioapic specific
> indicator that bootmem is done and the proper memory allocator is
> available, right?
Maybe a good name helps here. How about
bool hotplug = !!ioapic_initialized;
if (hotplug)
mp_irqdomain_create(idx);
Regards!
Gerry
>
> Aside of that is there a point to walk those tables before we actually
> can make any use of their content?
>
> Thanks,
>
> tglx
>
next prev parent reply other threads:[~2014-09-11 6:08 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 [this message]
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
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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