This patch cleans up all of the acpi_os_wait_events_complete() invocations to make it to be invoked inside of ACPICA in the way to accommodate Linux's work queue implementation. According to the report, current Linux kernel code is facing a boot time race issue in the acpi_remove_notify_handler(). This is because: Linux is using work queues to implement a deferred handler call environment while ACPICA expects OSPM to implement acpi_os_wait_events_complete() using wait queues. The position to invoke a "waiter" is not suitable for a "flusher" as new invocations can be scheduled after this position and before the deletion of the handler from its management container. Since the following commit has deleted acpi_os_wait_events_complete() parameters, it thus might not be possible for OSPM to achieve a safe removal using wait queues. This requires ACPICA to be changed accordingly to "flush" handlers rather than "wait" them to be drain up: Commit: 5ff986a2a9db11858247b71fe242fe17617229aa Date: Wed, 16 May 2012 13:36:07 -0700 Subject: Introduce acpi_os_wait_events_complete interface. This interface will block until asynchronous events like notifies and GPEs are complete. Within ACPICA, it is called before a notify or GPE handler is removed. ACPICA BZ 868. This patch fixes this issue by invoking acpi_os_wait_events_complete() in the way to "flush" things - it thus should be put to the position after handler is removed from its management container but before it is destructed. The technical concerns are: 1. MTX_NAMESPACE is used to protect things that acpi_os_wait_events_complete() might be waiting for, thus MTX_NAMESPACE must be unlocked before invoking acpi_os_wait_events_complete(). 2. MTX_NAMESPACE is also used to implement the serialization of acpi_install_notify_handler() and acpi_remove_notify_handler(). This patch changes this logic, thus if there are many acpi_install/remove_notify_handler() invoked in parallel, the acpi_os_wait_events_complete() might face the races which could cause it never running to an end. Normally this will require additional code to implement a separate locking facility which is not implemented due to 3. 3. Given ACPICA users will always invoke acpi_install_notify_handler() once during Linux module/device initialization and invoke acpi_remove_notify_handler() once during module/device finalization, problem stated in 2 will not happen in Linux environment due to the mutual exclusive module/device existence, this fix thus is sufficient. Same concerns can apply to acpi_install/remove_gpe_handler(). Reported and tested: Ronald Vink. Fixed: Lv Zheng. Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=60583 Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx> Reported-and-Tested-by: Ronald Vink <ronald.vink@xxxxxxxxxxxx> Signed-off-by: Bob Moore <robert.moore@xxxxxxxxx> --- drivers/acpi/acpica/evxface.c | 55 +++++++++++++++++++++++++++-------------- 1 file changed, 36 insertions(+), 19 deletions(-) diff --git a/drivers/acpi/acpica/evxface.c b/drivers/acpi/acpica/evxface.c index a41a0e7..11e5803 100644 --- a/drivers/acpi/acpica/evxface.c +++ b/drivers/acpi/acpica/evxface.c @@ -239,7 +239,7 @@ acpi_remove_notify_handler(acpi_handle device, union acpi_operand_object *obj_desc; union acpi_operand_object *handler_obj; union acpi_operand_object *previous_handler_obj; - acpi_status status; + acpi_status status = AE_OK; u32 i; ACPI_FUNCTION_TRACE(acpi_remove_notify_handler); @@ -251,20 +251,17 @@ acpi_remove_notify_handler(acpi_handle device, return_ACPI_STATUS(AE_BAD_PARAMETER); } - /* Make sure all deferred notify tasks are completed */ - - acpi_os_wait_events_complete(); - - status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE); - if (ACPI_FAILURE(status)) { - return_ACPI_STATUS(status); - } - /* Root Object. Global handlers are removed here */ if (device == ACPI_ROOT_OBJECT) { for (i = 0; i < ACPI_NUM_NOTIFY_TYPES; i++) { if (handler_type & (i + 1)) { + status = + acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE); + if (ACPI_FAILURE(status)) { + return_ACPI_STATUS(status); + } + if (!acpi_gbl_global_notify[i].handler || (acpi_gbl_global_notify[i].handler != handler)) { @@ -277,31 +274,40 @@ acpi_remove_notify_handler(acpi_handle device, acpi_gbl_global_notify[i].handler = NULL; acpi_gbl_global_notify[i].context = NULL; + + (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE); + + /* Make sure all deferred notify tasks are completed */ + + acpi_os_wait_events_complete(); } } - goto unlock_and_exit; + return_ACPI_STATUS(AE_OK); } /* All other objects: Are Notifies allowed on this object? */ if (!acpi_ev_is_notify_object(node)) { - status = AE_TYPE; - goto unlock_and_exit; + return_ACPI_STATUS(AE_TYPE); } /* Must have an existing internal object */ obj_desc = acpi_ns_get_attached_object(node); if (!obj_desc) { - status = AE_NOT_EXIST; - goto unlock_and_exit; + return_ACPI_STATUS(AE_NOT_EXIST); } /* Internal object exists. Find the handler and remove it */ for (i = 0; i < ACPI_NUM_NOTIFY_TYPES; i++) { if (handler_type & (i + 1)) { + status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE); + if (ACPI_FAILURE(status)) { + return_ACPI_STATUS(status); + } + handler_obj = obj_desc->common_notify.notify_list[i]; previous_handler_obj = NULL; @@ -329,10 +335,17 @@ acpi_remove_notify_handler(acpi_handle device, handler_obj->notify.next[i]; } + (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE); + + /* Make sure all deferred notify tasks are completed */ + + acpi_os_wait_events_complete(); acpi_ut_remove_reference(handler_obj); } } + return_ACPI_STATUS(status); + unlock_and_exit: (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE); return_ACPI_STATUS(status); @@ -842,10 +855,6 @@ acpi_remove_gpe_handler(acpi_handle gpe_device, return_ACPI_STATUS(AE_BAD_PARAMETER); } - /* Make sure all deferred GPE tasks are completed */ - - acpi_os_wait_events_complete(); - status = acpi_ut_acquire_mutex(ACPI_MTX_EVENTS); if (ACPI_FAILURE(status)) { return_ACPI_STATUS(status); @@ -897,9 +906,17 @@ acpi_remove_gpe_handler(acpi_handle gpe_device, (void)acpi_ev_add_gpe_reference(gpe_event_info); } + acpi_os_release_lock(acpi_gbl_gpe_lock, flags); + (void)acpi_ut_release_mutex(ACPI_MTX_EVENTS); + + /* Make sure all deferred GPE tasks are completed */ + + acpi_os_wait_events_complete(); + /* Now we can free the handler object */ ACPI_FREE(handler); + return_ACPI_STATUS(status); unlock_and_exit: acpi_os_release_lock(acpi_gbl_gpe_lock, flags); -- 1.7.10 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
