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Date:   Mon, 23 Sep 2019 10:28:27 +0200
From:   Lukas Wunner <lukas@wunner.de>
To:     Mika Westerberg <mika.westerberg@linux.intel.com>
Cc:     Bjorn Helgaas <bhelgaas@google.com>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Keith Busch <keith.busch@intel.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Frederick Lawler <fred@fredlawl.com>,
        "Gustavo A . R . Silva" <gustavo@embeddedor.com>,
        Sinan Kaya <okaya@kernel.org>,
        Kai-Heng Feng <kai.heng.feng@canonical.com>,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] PCI: pciehp: Prevent deadlock on disconnect
Message-ID: <20190923082827.mfss42uizrjtalhb@wunner.de>
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On Mon, Sep 23, 2019 at 11:12:37AM +0300, Mika Westerberg wrote:
> Regarding suggestion of unbinding PCI drivers without
> pci_lock_rescan_remove() hold, I haven't looked it too closely but I
> think we need to take that lock anyway because when we are unbinding a
> hotplug driver it is supposed to remove the hierarchy below touching the
> shared structures, possibly concurrently. Unfortunately there is no
> documentation what data pci_lock_rescan_remove() actually protects so
> first one needs to understand that. I think one way to clean up this is
> to use finer grained locking (with documented lock ordering) for PCI bus
> structures that can be accessed simultaneusly by different threads. But
> that is not a simple task.

Right.  I'm (still) working on that, albeit slowly as I'm caught up with
other stuff.

Thanks,

Lukas