From: Bjorn Helgaas <helgaas@kernel.org>
To: Lukas Wunner <lukas@wunner.de>
Cc: Ian May <ian.may@canonical.com>, linux-pci@vger.kernel.org
Subject: Re: [PATCH 1/2] PCIe hotplug interrupt and AER deadlock with reset_lock and device_lock
Date: Tue, 14 Jul 2020 18:58:11 -0500 [thread overview]
Message-ID: <20200714235811.GA431846@bjorn-Precision-5520> (raw)
In-Reply-To: <20200615185650.mzxndbw7ghvh5qiv@wunner.de>
On Mon, Jun 15, 2020 at 08:56:50PM +0200, Lukas Wunner wrote:
> On Mon, Jun 15, 2020 at 09:32:49AM -0500, Ian May wrote:
> > Currently when a hotplug interrupt and AER recovery triggers simultaneously
> > the following deadlock can occur.
> >
> > Hotplug AER
> > ---------------------------- ---------------------------
> > device_lock(&dev->dev) down_write(&ctrl->reset_lock)
> > down_read(&ctrl->reset_lock) device_lock(&dev->dev)
> >
> > This patch adds a reset_lock and reset_unlock hotplug_slot_op.
> > This would allow the controller reset_lock/reset_unlock to be moved
> > from pciehp_reset_slot to pci_slot_reset function allowing the controller
> > reset_lock to be acquired before the device lock allowing for both hotplug
> > and AER to grab the reset_lock and device lock in proper order.
>
> I've posted a patch to address such issues on Mar 31, just haven't
> gotten around to respin it with a proper commit message:
>
> https://lore.kernel.org/linux-pci/20200331130139.46oxbade6rcbaicb@wunner.de/
>
> I've solved it by moving the reset lock into struct pci_slot.
> I think that's simpler than adding two callbacks.
>
> Do you think the AER deadlock could be fixed based on my approach?
How should we proceed on this?
next prev parent reply other threads:[~2020-07-14 23:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-15 14:32 [PATCH 0/2] Hotplug interrupt and AER recovery deadlocks Ian May
2020-06-15 14:32 ` [PATCH 1/2] PCIe hotplug interrupt and AER deadlock with reset_lock and device_lock Ian May
2020-06-15 18:56 ` Lukas Wunner
2020-06-16 17:13 ` Ian May
2020-07-17 5:20 ` Lukas Wunner
[not found] ` <CAE1ug=a8PJpKh0Jx2ZZxo5kwQvvK883xs+mzyMWbW8T1oqyKDg@mail.gmail.com>
2020-08-01 16:14 ` Lukas Wunner
2020-07-14 23:58 ` Bjorn Helgaas [this message]
2020-06-15 14:32 ` [PATCH 2/2] PCIe hotplug interrupt and AER pci_slot_mutex deadlock Ian May
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