linux-kernel - Re: [PATCH 1/1] PCI: Fix lock symmetry in pci_slot

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Message-ID: <aBIjqwn7Txl6TuP0@wunner.de>
Date: Wed, 30 Apr 2025 15:20:43 +0200
From: Lukas Wunner <lukas@...ner.de>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, Keith Busch <kbusch@...nel.org>,
	Dave Jiang <dave.jiang@...el.com>,
	Dan Williams <dan.j.williams@...el.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] PCI: Fix lock symmetry in pci_slot_unlock()

On Wed, Apr 30, 2025 at 11:35:26AM +0300, Ilpo Järvinen wrote:
> The commit a4e772898f8b ("PCI: Add missing bridge lock to
> pci_bus_lock()") made the lock function to call depend on
> dev->subordinate but left pci_slot_unlock() unmodified creating locking
> asymmetry compared with pci_slot_lock().

Worth noting that this isn't just for symmetry:  It seems the bridge
is unlocked twice because pci_bus_unlock() unlocks bus->self and
pci_slot_unlock() then unconditionally unlocks the same bridge device
again.

Thanks,

Lukas