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Date: Mon, 5 May 2025 14:57:49 +0200
From: Lukas Wunner <lukas@wunner.de>
To: Ilpo =?iso-8859-1?Q?J=E4rvinen?= <ilpo.jarvinen@linux.intel.com>
Cc: Moshe Shemesh <moshe@nvidia.com>, Bjorn Helgaas <bhelgaas@google.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Keith Busch <kbusch@kernel.org>, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/1] PCI: Fix lock symmetry in pci_slot_unlock()
Message-ID: <aBi1zYVNQ5qHbC4f@wunner.de>
References: <20250505115412.37628-1-ilpo.jarvinen@linux.intel.com>
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In-Reply-To: <20250505115412.37628-1-ilpo.jarvinen@linux.intel.com>

On Mon, May 05, 2025 at 02:54:12PM +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().
> 
> Because of the asymmetric lock handling, the same bridge device is
> unlocked twice. First pci_bus_unlock() unlocks bus->self and then
> pci_slot_unlock() will unconditionally unlock the same bridge device.
> 
> Move pci_dev_unlock() inside an else branch to match the logic in
> pci_slot_lock().
> 
> Fixes: a4e772898f8b ("PCI: Add missing bridge lock to pci_bus_lock()")
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> Cc: <stable@vger.kernel.org>

Reviewed-by: Lukas Wunner <lukas@wunner.de>