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

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

[Rafael J. Wysocki]

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>
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);

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

[Toshi Kani]

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);
> 

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

[Rafael J. Wysocki]

On Tuesday, June 18, 2013 03:28:37 PM Toshi Kani wrote:
> 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!


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.