From: wangyijing <wangyijing@huawei.com>
To: Guenter Roeck <linux@roeck-us.net>, Bjorn Helgaas <bhelgaas@google.com>
Cc: <linux-pci@vger.kernel.org>, <rajatja@google.com>, <rjw@rjwysocki.net>
Subject: Re: [PATCH v2 1/2] PCI: Use a local mutex instead of pci_bus_sem to avoid deadlock
Date: Fri, 24 Jul 2015 12:08:33 +0800 [thread overview]
Message-ID: <55B1BA41.4080700@huawei.com> (raw)
In-Reply-To: <55B1ABF3.9070201@roeck-us.net>
在 2015/7/24 11:07, Guenter Roeck 写道:
> On 07/17/2015 02:16 AM, Yijing Wang wrote:
>> Rajat Jain reported a deadlock when a hierarchical hot plug
>> thread and aer recovery thread both run.
>> https://lkml.org/lkml/2015/3/11/861
>>
>> thread 1:
>> pciehp_enable_slot()
>> pciehp_configure_device()
>> pci_bus_add_devices()
>> device_attach(dev)
>> device_lock(dev) //acquire device mutex successfully
>> ...
>> pciehp_probe(dev)
>> __pci_hp_register()
>> pci_create_slot()
>> down_write(pci_bus_sem) //deadlock here
>>
>> thread 2:
>> aer_isr_one_error()
>> aer_process_err_device()
>> do_recovery()
>> broadcast_error_message()
>> pci_walk_bus()
>> down_read(&pci_bus_sem) //acquire pci_bus_sem successfully
>> report_error_detected(dev)
>> device_lock(dev) // deadlock here
>>
>> We use down_write(&pci_bus_sem) to protect the bus->slots list, because the
>> bus->slots list is only accessed in drivers/pci/slot.c, we could introduce
>> a new local mutex to protect bus->slots, and use down_read(&pci_bus_sem)
>> instead of down_write(&pci_bus_sem) to protect the bus->devices list.
>>
>> Signed-off-by: Yijing Wang <wangyijing@huawei.com>
>
> I applied both patches to our system and ran a number of tests.
> Works fine as far as I can see.
>
> Tested-by: Guenter Roeck <linux@roeck-us.net>
Guenter, thanks very much!
Thanks!
Yijing.
>
>
>
next prev parent reply other threads:[~2015-07-24 4:09 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-17 9:16 [PATCH v2 0/2] Fix a deadlock for aer and pciehp driver Yijing Wang
2015-07-17 9:16 ` [PATCH v2 1/2] PCI: Use a local mutex instead of pci_bus_sem to avoid deadlock Yijing Wang
2015-07-24 3:07 ` Guenter Roeck
2015-07-24 4:08 ` wangyijing [this message]
2015-07-17 9:16 ` [PATCH v2 2/2] PCI: Lock pci_slot_mutex when traverse bus->slots Yijing Wang
2015-07-18 3:50 ` [PATCH v2 0/2] Fix a deadlock for aer and pciehp driver Guenter Roeck
2015-07-30 21:20 ` Bjorn Helgaas
2015-07-31 1:37 ` Guenter Roeck
2015-07-31 15:31 ` Bjorn Helgaas
2015-08-10 19:29 ` Bjorn Helgaas
2015-08-11 1:07 ` wangyijing
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