LinuxLists.cc - [PATCH] ACPI: OSL: Prevent acpi_release

2020-08-21 17:44:27

Subject: [PATCH] ACPI: OSL: Prevent acpi_release_memory() from returning too early

From: Rafael J. Wysocki <[email protected]>

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 <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
---
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);

2020-08-21 18:46:14

by Kenneth Crudup

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Subject: Re: [PATCH] ACPI: OSL: Prevent acpi_release_memory() from returning too early

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 <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: Rafael J. Wysocki <[email protected]>
> ---
> 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);
>
>
>
>
>

--
Kenneth R. Crudup Sr. SW Engineer, Scott County Consulting, Orange County CA

2020-08-24 09:31:16

by Heikki Krogerus

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Subject: Re: [PATCH] ACPI: OSL: Prevent acpi_release_memory() from returning too early

On Fri, Aug 21, 2020 at 07:42:55PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: Rafael J. Wysocki <[email protected]>

FWIW:

Reviewed-by: Heikki Krogerus <[email protected]>

> ---
> 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,

--
heikki

2020-08-24 14:08:27

by Mika Westerberg

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