RE: [PATCH 04/11] ACPICA: Events: Fix acpi_ev_initialize_region() return value

From: Zheng, Lv
Date: Thu Dec 01 2016 - 03:00:46 EST

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Hi, Rafael

> From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi-owner@xxxxxxxxxxxxxxx] On Behalf Of Rafael J.
> Wysocki
> 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@xxxxxxxxx> 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@xxxxxxxxx>
> > Signed-off-by: Bob Moore <robert.moore@xxxxxxxxx>
> > ---
> > 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.

This commit only changes returning value.
Lock changes are not included.

We never invokes acpi_ev_initialize_region with acpi_ns_locked=true.
So all if (acpi_ns_locked) code pieces are useless and deleted in this commit.

>
> > 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.
>

acpi_ex_exit_interpreter() / acpi_ex_enter_interpreter() are not-modified-lines.
Please check again.

Unlock before _REG is the minimum requirement as ACPICA will reacquire interpreter lock when _REG is evaluated.
Before applying the following commit (which is in the upstream):
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=8633db6b02
ACPICA unlocks the entire walk namespace process.

However this change did nothing to the locks.
Only changed the returning value of acpi_ev_initialize_region().
Always returning AE_OK instead of AE_NOT_EXIST.
Other than this, changes are no-ops.

Thanks and best regards
Lv

>
> > -
> > - 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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Next message: Marcin Nowakowski: "[PATCH] drivers/of: fix missing pr_cont()s in of_print_phandle_args"
Previous message: Ulf Hansson: "Re: [PATCH] mmc: queue: add #ifdef around bounce buffer code"
Next in thread: Rafael J. Wysocki: "Re: [PATCH 04/11] ACPICA: Events: Fix acpi_ev_initialize_region() return value"
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