linux-kernel - Re: [PATCH V2] PCI: AER: fix deadlock in do

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Message-ID: <a9b14502-4ac6-58dc-89ee-a91354f4d2da@codeaurora.org>
Date:   Sat, 30 Sep 2017 09:31:35 -0400
From:   Sinan Kaya <okaya@...eaurora.org>
To:     Govindarajulu Varadarajan <gvaradar@...co.com>, benve@...co.com,
        bhelgaas@...gle.com, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, jlbec@...lplan.org, hch@....de,
        mingo@...hat.com, peterz@...radead.org
Subject: Re: [PATCH V2] PCI: AER: fix deadlock in do_recovery

On 9/30/2017 1:49 AM, Govindarajulu Varadarajan wrote:
> This patch does a pci_bus_walk and adds all the devices to a list. After
> unlocking (up_read) &pci_bus_sem, we go through the list and call
> err_handler of the devices with devic_lock() held. This way, we dont try
> to hold both locks at same time.

I do like this approach with some more feedback.

I need a little bit of help here from someone that knows get/put device calls.

I understand get_device() and put_device() are there to increment/decrement
reference counters. This patch seems to use them as an alternative for device_lock()
and device_unlock() API. 

If this is a good assumption, then you can get away with just replacing device_lock()
with get_device() and device_unlock() with put_device() in the existing code as
well. Then, you don't need to build a linklist.

A nit is your history messages in the commit message belongs to a cover letter.

-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.