Re: [PATCH v2 1/1] PCI: Fix lock symmetry in pci_slot_unlock()

[Dave Jiang <dave.jiang@intel.com>]

On 5/5/25 4:54 AM, 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: Dave Jiang <dave.jiang@intel.com>
> ---
> 
> v2:
> - Improve changelog (Lukas)
> - Added Cc stable
> 
>  drivers/pci/pci.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 4d7c9f64ea24..26507aa906d7 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -5542,7 +5542,8 @@ static void pci_slot_unlock(struct pci_slot *slot)
>  			continue;
>  		if (dev->subordinate)
>  			pci_bus_unlock(dev->subordinate);
> -		pci_dev_unlock(dev);
> +		else
> +			pci_dev_unlock(dev);
>  	}
>  }
>  
> 
> base-commit: 0af2f6be1b4281385b618cb86ad946eded089ac8