Re: [PATCH 00/11] Enhancements and bugfixes to PCI hotplug subsystem

[Jiang Liu <liuj97@gmail.com>]

Hi Kenji,
	Thanks for your comments!
	As you have mentioned, I have a TODO list for all PCI hotplug drivers 
under drivers/pci/hotplug. I plan to modify those drivers after doing stress
tests against the acpiphp driver. But one difficulty I'm facing is to find 
hardware platforms to test those hotplug drivers, currently I could only find
platforms to test the acpiphp and pcie hotplug drivers.
	For the lock granularity issue,	I have thought about providing a more
fine-grained lock schema, such as "branch lock" which locks PCI sub trees. 
But that solution needs much more changes and careful inspection over
the PCI code to avoid deadlock issues. So I think it would be better for us
to globally serialize all PCI hotplug operations first and optimize the lock
schema in future. Is that OK to you?
	Thanks!
	Gerry

On 03/27/2012 11:33 AM, Kenji Kaneshige wrote:
>> The second prososal is to introduce a recursive mutex lock to
>> serialize all hotplug operations triggered by sysfs interfaces,
>> PCI HPC hardware events, ACPI hotplug events and other sources.
> 
> The pciehp (and other hotplug controllers) needs this too.
> 
> There is only one mutex in the current implementation. I think it
> would be better if we can have the mutex per host bridge or per bus
> or something so that we can run multiple hot-plug operation in
> parallel on the independent PCI sub trees.
> 
> Regards,
> Kenji Kaneshige
> 
> 
> 
> (2012/03/23 23:58), Jiang Liu wrote:
>> This is a series of RFC patches, to make sure we are doing the
>> right thing in the right way.  The patchset hasn't been tested yet.
>> There are several minor bugfixes and two proposals.
>>
>> The first proposal is to add notification chain for PCI hotplug events,
>> so other components interested in PCI root/bus/device hotplug events
>> could subscribe to the chain.
>>
>> The second prososal is to introduce a recursive mutex lock to
>> serialize all hotplug operations triggered by sysfs interfaces,
>> PCI HPC hardware events, ACPI hotplug events and other sources.
>>
>> There are still works left in driver/pci/hotplug directory to apply
>> the above two proposals.
>>
>> The patchset applies to Yinghai's work on PCI root bus hotplug at
>> git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-yinghai.git for-x86-irq
>> And it depends on my previous patchset, please refer to
>> http://www.spinics.net/lists/linux-pci/msg14472.html
>>
>> Thanks!
>>
>> Jiang Liu (11):
>>    PCI: Fix device reference count leakage in pci_dev_present()
>>    PCI: introduce pci_bus_get()/pci_bus_put() to hide implementation
>>      details
>>    PCI: clean up root bridge related logic in acpiphp driver
>>    ACPI,PCI: fix race windows caused by alloc_acpi_hotplug_work()
>>    PCI: Add notification interfaces for PCI root/bus/device hotplug
>>      events
>>    ACPI,PCI: update ACPI<->PCI binding information when pci hotplug
>>      event happens
>>    ACPI,PCI: update ACPI slots when PCI hotplug event happens
>>    PCI: Introduce recursive mutex to serialize PCI hotplug operations
>>    PCI: serialize hotplug operations triggered by PCI hotplug sysfs
>>      interfaces
>>    PCI,ACPI: serialize hotplug operations triggered by ACPI subsystem
>>    PCI: Serialize hotplug operations triggered by acpiphp driver
>>
>>   drivers/acpi/pci_bind.c                |  115 +++++++++++++++++++++++++
>>   drivers/acpi/pci_root.c                |    8 ++
>>   drivers/acpi/pci_slot.c                |   81 ++++++++++++++++++-
>>   drivers/pci/bus.c                      |   20 ++++-
>>   drivers/pci/hotplug.c                  |   47 +++++++++++
>>   drivers/pci/hotplug/acpiphp.h          |    7 ++-
>>   drivers/pci/hotplug/acpiphp_glue.c     |  143 ++++++++++++--------------------
>>   drivers/pci/hotplug/pci_hotplug_core.c |    2 +
>>   drivers/pci/pci-sysfs.c                |   29 +++----
>>   drivers/pci/pci.h                      |    8 ++
>>   drivers/pci/probe.c                    |   10 ++-
>>   drivers/pci/remove.c                   |   20 ++++-
>>   drivers/pci/search.c                   |   10 +-
>>   include/linux/pci.h                    |   57 +++++++++++++
>>   14 files changed, 437 insertions(+), 120 deletions(-)
>>
>