From d0515d9fec68bace144fda57a69f4268fb875209 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Thu, 6 Jan 2011 23:38:57 +0100 Subject: ACPI / PM: Check status of power resources under mutexes It certainly is not a good idea to execute _ON or _OFF and _STA for the same power resource at the same time which may happen in some circumstances in theory. To prevent that from happening, read the power state of each power resource under its mutex, as that will prevent the state from being changed at the same time. Signed-off-by: Rafael J. Wysocki Signed-off-by: Len Brown --- drivers/acpi/power.c | 33 ++++++++++++++++++++------------- 1 file changed, 20 insertions(+), 13 deletions(-) (limited to 'drivers/acpi') diff --git a/drivers/acpi/power.c b/drivers/acpi/power.c index ac02af4..9ac2a9f 100644 --- a/drivers/acpi/power.c +++ b/drivers/acpi/power.c @@ -145,9 +145,8 @@ static int acpi_power_get_state(acpi_handle handle, int *state) static int acpi_power_get_list_state(struct acpi_handle_list *list, int *state) { - int result = 0, state1; - u32 i = 0; - + int cur_state; + int i = 0; if (!list || !state) return -EINVAL; @@ -155,25 +154,33 @@ static int acpi_power_get_list_state(struct acpi_handle_list *list, int *state) /* The state of the list is 'on' IFF all resources are 'on'. */ for (i = 0; i < list->count; i++) { - /* - * The state of the power resource can be obtained by - * using the ACPI handle. In such case it is unnecessary to - * get the Power resource first and then get its state again. - */ - result = acpi_power_get_state(list->handles[i], &state1); + struct acpi_power_resource *resource; + acpi_handle handle = list->handles[i]; + int result; + + result = acpi_power_get_context(handle, &resource); if (result) return result; - *state = state1; + mutex_lock(&resource->resource_lock); - if (*state != ACPI_POWER_RESOURCE_STATE_ON) + result = acpi_power_get_state(handle, &cur_state); + + mutex_unlock(&resource->resource_lock); + + if (result) + return result; + + if (cur_state != ACPI_POWER_RESOURCE_STATE_ON) break; } ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource list is %s\n", - *state ? "on" : "off")); + cur_state ? "on" : "off")); - return result; + *state = cur_state; + + return 0; } static int __acpi_power_on(struct acpi_power_resource *resource) -- cgit v1.1