Re: [PATCH] ACPI / dock: Take ACPI scan lock in write_undock()

[Toshi Kani <toshi.kani@hp.com>]

On Sun, 2013-06-16 at 00:16 +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> Since commit 3757b94 (ACPI / hotplug: Fix concurrency issues and
> memory leaks) acpi_bus_scan() and acpi_bus_trim() must always be
> called under acpi_scan_lock, but currently the following scenario
> violating that requirement is possible:
> 
>  write_undock()
>   handle_eject_request()
>    hotplug_dock_devices()
>     dock_remove_acpi_device()
>      acpi_bus_trim()
> 
> Fix that by making write_undock() acquire acpi_scan_lock before
> calling handle_eject_request() as appropriate (begin_undock() is
> under the lock too in analogy with acpi_dock_deferred_cb()).
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Looks good.

Acked-by: Toshi Kani <toshi.kani@hp.com>

Thanks,
-Toshi



> Cc: 3.9+ <stable@vger.kernel.org>
> ---
>  drivers/acpi/dock.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> Index: linux-pm/drivers/acpi/dock.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/dock.c
> +++ linux-pm/drivers/acpi/dock.c
> @@ -868,8 +868,10 @@ static ssize_t write_undock(struct devic
>  	if (!count)
>  		return -EINVAL;
>  
> +	acpi_scan_lock_acquire();
>  	begin_undock(dock_station);
>  	ret = handle_eject_request(dock_station, ACPI_NOTIFY_EJECT_REQUEST);
> +	acpi_scan_lock_release();
>  	return ret ? ret: count;
>  }
>  static DEVICE_ATTR(undock, S_IWUSR, NULL, write_undock);
>