ACPI: OSL: Prevent acpi_release_memory() from returning too early

1293215 diff mbox series

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

After commit 1757659d022b ("ACPI: OSL: Implement deferred unmapping
of ACPI memory") in some cases acpi_release_memory() may return
before the target memory mappings actually go away, because they
are released asynchronously now.

Prevent it from returning prematurely by making it wait for the next
RCU grace period to elapse, for all of the RCU callbacks to complete
and for all of the scheduled work items to be flushed before
returning.

Fixes: 1757659d022b ("ACPI: OSL: Implement deferred unmapping of ACPI memory")
Reported-by: Kenneth R. Crudup <kenny@panix.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/osl.c |   19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

Works here for me:

----
$ l /sys/class/typec
total 0
10012 0 drwxr-xr-x  2 root root 0 Aug 21 11:25 ./
   10 0 drwxr-xr-x 67 root root 0 Aug 21 11:25 ../
27771 0 lrwxrwxrwx  1 root root 0 Aug 21 11:25 port0 -> ../../devices/platform/USBC000:00/typec/port0/
35601 0 lrwxrwxrwx  1 root root 0 Aug 21 11:25 port0-partner -> ../../devices/platform/USBC000:00/typec/port0/port0-partner/
36686 0 lrwxrwxrwx  1 root root 0 Aug 21 11:25 port1 -> ../../devices/platform/USBC000:00/typec/port1/
$
----

On Fri, 21 Aug 2020, Rafael J. Wysocki wrote:

> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> After commit 1757659d022b ("ACPI: OSL: Implement deferred unmapping
> of ACPI memory") in some cases acpi_release_memory() may return
> before the target memory mappings actually go away, because they
> are released asynchronously now.
>
> Prevent it from returning prematurely by making it wait for the next
> RCU grace period to elapse, for all of the RCU callbacks to complete
> and for all of the scheduled work items to be flushed before
> returning.
>
> Fixes: 1757659d022b ("ACPI: OSL: Implement deferred unmapping of ACPI memory")
> Reported-by: Kenneth R. Crudup <kenny@panix.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>  drivers/acpi/osl.c |   19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
>
> Index: linux-pm/drivers/acpi/osl.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/osl.c
> +++ linux-pm/drivers/acpi/osl.c
> @@ -1575,11 +1575,26 @@ static acpi_status acpi_deactivate_mem_r
>  acpi_status acpi_release_memory(acpi_handle handle, struct resource *res,
>  				u32 level)
>  {
> +	acpi_status status;
> +
>  	if (!(res->flags & IORESOURCE_MEM))
>  		return AE_TYPE;
>
> -	return acpi_walk_namespace(ACPI_TYPE_REGION, handle, level,
> -				   acpi_deactivate_mem_region, NULL, res, NULL);
> +	status = acpi_walk_namespace(ACPI_TYPE_REGION, handle, level,
> +				     acpi_deactivate_mem_region, NULL,
> +				     res, NULL);
> +	if (ACPI_FAILURE(status))
> +		return status;
> +
> +	/*
> +	 * Wait for all of the mappings queued up for removal by
> +	 * acpi_deactivate_mem_region() to actually go away.
> +	 */
> +	synchronize_rcu();
> +	rcu_barrier();
> +	flush_scheduled_work();
> +
> +	return AE_OK;
>  }
>  EXPORT_SYMBOL_GPL(acpi_release_memory);
>
>
>
>
>

On Fri, Aug 21, 2020 at 07:42:55PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> After commit 1757659d022b ("ACPI: OSL: Implement deferred unmapping
> of ACPI memory") in some cases acpi_release_memory() may return
> before the target memory mappings actually go away, because they
> are released asynchronously now.
> 
> Prevent it from returning prematurely by making it wait for the next
> RCU grace period to elapse, for all of the RCU callbacks to complete
> and for all of the scheduled work items to be flushed before
> returning.
> 
> Fixes: 1757659d022b ("ACPI: OSL: Implement deferred unmapping of ACPI memory")
> Reported-by: Kenneth R. Crudup <kenny@panix.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

FWIW:

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
>  drivers/acpi/osl.c |   19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 
> Index: linux-pm/drivers/acpi/osl.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/osl.c
> +++ linux-pm/drivers/acpi/osl.c
> @@ -1575,11 +1575,26 @@ static acpi_status acpi_deactivate_mem_r
>  acpi_status acpi_release_memory(acpi_handle handle, struct resource *res,
>  				u32 level)
>  {
> +	acpi_status status;
> +
>  	if (!(res->flags & IORESOURCE_MEM))
>  		return AE_TYPE;
>  
> -	return acpi_walk_namespace(ACPI_TYPE_REGION, handle, level,
> -				   acpi_deactivate_mem_region, NULL, res, NULL);
> +	status = acpi_walk_namespace(ACPI_TYPE_REGION, handle, level,
> +				     acpi_deactivate_mem_region, NULL,
> +				     res, NULL);
> +	if (ACPI_FAILURE(status))
> +		return status;
> +
> +	/*
> +	 * Wait for all of the mappings queued up for removal by
> +	 * acpi_deactivate_mem_region() to actually go away.
> +	 */
> +	synchronize_rcu();
> +	rcu_barrier();
> +	flush_scheduled_work();
> +
> +	return AE_OK;
>  }
>  EXPORT_SYMBOL_GPL(acpi_release_memory);

thanks,

On Fri, Aug 21, 2020 at 07:42:55PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> After commit 1757659d022b ("ACPI: OSL: Implement deferred unmapping
> of ACPI memory") in some cases acpi_release_memory() may return
> before the target memory mappings actually go away, because they
> are released asynchronously now.
> 
> Prevent it from returning prematurely by making it wait for the next
> RCU grace period to elapse, for all of the RCU callbacks to complete
> and for all of the scheduled work items to be flushed before
> returning.
> 
> Fixes: 1757659d022b ("ACPI: OSL: Implement deferred unmapping of ACPI memory")
> Reported-by: Kenneth R. Crudup <kenny@panix.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>