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Date:   Thu, 1 Dec 2016 00:07:57 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Lv Zheng <lv.zheng@...el.com>
Cc:     "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <len.brown@...el.com>, Lv Zheng <zetalog@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Bob Moore <robert.moore@...el.com>
Subject: Re: [PATCH 04/11] ACPICA: Events: Fix acpi_ev_initialize_region()
 return value

On Wed, Nov 30, 2016 at 8:21 AM, Lv Zheng <lv.zheng@...el.com> wrote:
> ACPICA commit 543342ab7a676f4eb0c9f100d349388a84dff0e8
>
> This patch changes acpi_ev_initialize_region(), stop returning AE_NOT_EXIST
> from it so that, not only in acpi_ds_load2_end_op(), but all places invoking
> this function won't emit exceptions. The exception can be seen in
> acpi_ds_initialize_objects() when certain table loading mode is chosen.
>
> This patch also removes useless acpi_ns_locked from acpi_ev_initialize_region()
> as this function will always be invoked with interpreter lock held now, and
> the lock granularity has been tuned to lock around _REG execution, thus it
> is now handled by acpi_ex_exit_interpreter(). Lv Zheng.
>
> Link: https://github.com/acpica/acpica/commit/543342ab
> Signed-off-by: Lv Zheng <lv.zheng@...el.com>
> Signed-off-by: Bob Moore <robert.moore@...el.com>
> ---
>  drivers/acpi/acpica/acevents.h |    4 +--
>  drivers/acpi/acpica/dsopcode.c |    2 +-
>  drivers/acpi/acpica/dswload2.c |   13 +--------
>  drivers/acpi/acpica/evrgnini.c |   59 ++++++++++++++++------------------------
>  4 files changed, 27 insertions(+), 51 deletions(-)
>
> diff --git a/drivers/acpi/acpica/acevents.h b/drivers/acpi/acpica/acevents.h
> index 92fa47c..8a0049d 100644
> --- a/drivers/acpi/acpica/acevents.h
> +++ b/drivers/acpi/acpica/acevents.h
> @@ -243,9 +243,7 @@ union acpi_operand_object *acpi_ev_find_region_handler(acpi_adr_space_type
>                              u32 function,
>                              void *handler_context, void **region_context);
>
> -acpi_status
> -acpi_ev_initialize_region(union acpi_operand_object *region_obj,
> -                         u8 acpi_ns_locked);
> +acpi_status acpi_ev_initialize_region(union acpi_operand_object *region_obj);
>
>  /*
>   * evsci - SCI (System Control Interrupt) handling/dispatch
> diff --git a/drivers/acpi/acpica/dsopcode.c b/drivers/acpi/acpica/dsopcode.c
> index 4cc9d98..77fd7c8 100644
> --- a/drivers/acpi/acpica/dsopcode.c
> +++ b/drivers/acpi/acpica/dsopcode.c
> @@ -84,7 +84,7 @@ acpi_status acpi_ds_initialize_region(acpi_handle obj_handle)
>
>         /* Namespace is NOT locked */
>
> -       status = acpi_ev_initialize_region(obj_desc, FALSE);
> +       status = acpi_ev_initialize_region(obj_desc);
>         return (status);
>  }
>
> diff --git a/drivers/acpi/acpica/dswload2.c b/drivers/acpi/acpica/dswload2.c
> index e362182..651f35a 100644
> --- a/drivers/acpi/acpica/dswload2.c
> +++ b/drivers/acpi/acpica/dswload2.c
> @@ -609,18 +609,7 @@ acpi_status acpi_ds_load2_end_op(struct acpi_walk_state *walk_state)
>
>                         status =
>                             acpi_ev_initialize_region
> -                           (acpi_ns_get_attached_object(node), FALSE);
> -
> -                       if (ACPI_FAILURE(status)) {
> -                               /*
> -                                *  If AE_NOT_EXIST is returned, it is not fatal
> -                                *  because many regions get created before a handler
> -                                *  is installed for said region.
> -                                */
> -                               if (AE_NOT_EXIST == status) {
> -                                       status = AE_OK;
> -                               }
> -                       }
> +                           (acpi_ns_get_attached_object(node));

This hunk doesn't apply for me.

We have acpi_ex_exit_interpreter() / acpi_ex_enter_interpreter()
around the acpi_ev_initialize_region() in linux-next.

>                         break;
>
>                 case AML_NAME_OP:
> diff --git a/drivers/acpi/acpica/evrgnini.c b/drivers/acpi/acpica/evrgnini.c
> index 75ddd16..a909225 100644
> --- a/drivers/acpi/acpica/evrgnini.c
> +++ b/drivers/acpi/acpica/evrgnini.c
> @@ -479,7 +479,6 @@ static u8 acpi_ev_is_pci_root_bridge(struct acpi_namespace_node *node)
>   * FUNCTION:    acpi_ev_initialize_region
>   *
>   * PARAMETERS:  region_obj      - Region we are initializing
> - *              acpi_ns_locked  - Is namespace locked?
>   *
>   * RETURN:      Status
>   *
> @@ -497,19 +496,28 @@ static u8 acpi_ev_is_pci_root_bridge(struct acpi_namespace_node *node)
>   * MUTEX:       Interpreter should be unlocked, because we may run the _REG
>   *              method for this region.
>   *
> + * NOTE:        Possible incompliance:
> + *              There is a behavior conflict in automatic _REG execution:
> + *              1. When the interpreter is evaluating a method, we can only
> + *                 automatically run _REG for the following case:
> + *                   operation_region (OPR1, 0x80, 0x1000010, 0x4)
> + *              2. When the interpreter is loading a table, we can also
> + *                 automatically run _REG for the following case:
> + *                   operation_region (OPR1, 0x80, 0x1000010, 0x4)
> + *              Though this may not be compliant to the de-facto standard, the
> + *              logic is kept in order not to trigger regressions. And keeping
> + *              this logic should be taken care by the caller of this function.
> + *
>   ******************************************************************************/
>
> -acpi_status
> -acpi_ev_initialize_region(union acpi_operand_object *region_obj,
> -                         u8 acpi_ns_locked)
> +acpi_status acpi_ev_initialize_region(union acpi_operand_object *region_obj)
>  {
>         union acpi_operand_object *handler_obj;
>         union acpi_operand_object *obj_desc;
>         acpi_adr_space_type space_id;
>         struct acpi_namespace_node *node;
> -       acpi_status status;
>
> -       ACPI_FUNCTION_TRACE_U32(ev_initialize_region, acpi_ns_locked);
> +       ACPI_FUNCTION_TRACE(ev_initialize_region);
>
>         if (!region_obj) {
>                 return_ACPI_STATUS(AE_BAD_PARAMETER);
> @@ -580,39 +588,17 @@ static u8 acpi_ev_is_pci_root_bridge(struct acpi_namespace_node *node)
>                                                   handler_obj, region_obj,
>                                                   obj_desc));
>
> -                               status =
> -                                   acpi_ev_attach_region(handler_obj,
> -                                                         region_obj,
> -                                                         acpi_ns_locked);
> +                               (void)acpi_ev_attach_region(handler_obj,
> +                                                           region_obj, FALSE);
>
>                                 /*
>                                  * Tell all users that this region is usable by
>                                  * running the _REG method
>                                  */
> -                               if (acpi_ns_locked) {
> -                                       status =
> -                                           acpi_ut_release_mutex
> -                                           (ACPI_MTX_NAMESPACE);
> -                                       if (ACPI_FAILURE(status)) {
> -                                               return_ACPI_STATUS(status);
> -                                       }
> -                               }
> -
>                                 acpi_ex_exit_interpreter();
> -                               status =
> -                                   acpi_ev_execute_reg_method(region_obj,
> -                                                              ACPI_REG_CONNECT);
> +                               (void)acpi_ev_execute_reg_method(region_obj,
> +                                                                ACPI_REG_CONNECT);
>                                 acpi_ex_enter_interpreter();

And this also doesn't apply, because we don't invoke
acpi_ex_exit_interpreter() / acpi_ex_enter_interpreter() around the
acpi_ev_execute_reg_method() call in linux-next.


> -
> -                               if (acpi_ns_locked) {
> -                                       status =
> -                                           acpi_ut_acquire_mutex
> -                                           (ACPI_MTX_NAMESPACE);
> -                                       if (ACPI_FAILURE(status)) {
> -                                               return_ACPI_STATUS(status);
> -                                       }
> -                               }
> -
>                                 return_ACPI_STATUS(AE_OK);
>                         }
>                 }
> @@ -622,12 +608,15 @@ static u8 acpi_ev_is_pci_root_bridge(struct acpi_namespace_node *node)
>                 node = node->parent;
>         }
>
> -       /* If we get here, there is no handler for this region */
> -
> +       /*
> +        * If we get here, there is no handler for this region. This is not
> +        * fatal because many regions get created before a handler is installed
> +        * for said region.
> +        */
>         ACPI_DEBUG_PRINT((ACPI_DB_OPREGION,
>                           "No handler for RegionType %s(%X) (RegionObj %p)\n",
>                           acpi_ut_get_region_name(space_id), space_id,
>                           region_obj));
>
> -       return_ACPI_STATUS(AE_NOT_EXIST);
> +       return_ACPI_STATUS(AE_OK);
>  }
> --

Thanks,
Rafael

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