From 3ae45a27df74358b4bcd3d5a67e47ad734a48945 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Fri, 2 Nov 2012 13:09:08 +0100 Subject: [PATCH] ACPI: Make seemingly useless check in osl.c more understandable There is a seemingly useless check in drivers/acpi/osl.c added by commit bc73675 (ACPI: fixes a false alarm from lockdep), which really is necessary to avoid false positive lockdep complaints. Document this and rearrange the code related to it so that it makes fewer checks. Signed-off-by: Rafael J. Wysocki Acked-by: Yinghai Lu --- drivers/acpi/osl.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c index 7dfe91d0173e..6dc4a2b1e956 100644 --- a/drivers/acpi/osl.c +++ b/drivers/acpi/osl.c @@ -932,7 +932,7 @@ static acpi_status __acpi_os_execute(acpi_execute_type type, * having a static work_struct. */ - dpc = kmalloc(sizeof(struct acpi_os_dpc), GFP_ATOMIC); + dpc = kzalloc(sizeof(struct acpi_os_dpc), GFP_ATOMIC); if (!dpc) return AE_NO_MEMORY; @@ -944,17 +944,22 @@ static acpi_status __acpi_os_execute(acpi_execute_type type, * because the hotplug code may call driver .remove() functions, * which invoke flush_scheduled_work/acpi_os_wait_events_complete * to flush these workqueues. + * + * To prevent lockdep from complaining unnecessarily, make sure that + * there is a different static lockdep key for each workqueue by using + * INIT_WORK() for each of them separately. */ - queue = hp ? kacpi_hotplug_wq : - (type == OSL_NOTIFY_HANDLER ? kacpi_notify_wq : kacpid_wq); - dpc->wait = hp ? 1 : 0; - - if (queue == kacpi_hotplug_wq) + if (hp) { + queue = kacpi_hotplug_wq; + dpc->wait = 1; INIT_WORK(&dpc->work, acpi_os_execute_deferred); - else if (queue == kacpi_notify_wq) + } else if (type == OSL_NOTIFY_HANDLER) { + queue = kacpi_notify_wq; INIT_WORK(&dpc->work, acpi_os_execute_deferred); - else + } else { + queue = kacpid_wq; INIT_WORK(&dpc->work, acpi_os_execute_deferred); + } /* * On some machines, a software-initiated SMI causes corruption unless