ACPI: execute Notify() handlers on new thread

http://bugzilla.kernel.org/show_bug.cgi?id=5534

Thanks to Peter Wainwright for isolating the issue.
Thanks to Andi Kleen and Bob Moore for feedback.
Thanks to Richard Mace and others for testing.
Updates by Konstantin Karasyov.
Signed-off-by: NKonstantin Karasyov <konstantin.a.karasyov@intel.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

drivers/acpi/ec.c

@@ -763,8 +763,7 @@ static u32 acpi_ec_gpe_poll_handler(void *data)
 
 	acpi_disable_gpe(NULL, ec->common.gpe_bit, ACPI_ISR);
 
-	status = acpi_os_queue_for_execution(OSD_PRIORITY_GPE,
-					     acpi_ec_gpe_query, ec);
+	status = acpi_os_execute(OSL_EC_POLL_HANDLER, acpi_ec_gpe_query, ec);
 
 	if (status == AE_OK)
 		return ACPI_INTERRUPT_HANDLED;
@@ -799,7 +798,7 @@ static u32 acpi_ec_gpe_intr_handler(void *data)
 
 	if (value & ACPI_EC_FLAG_SCI) {
 		atomic_add(1, &ec->intr.pending_gpe);
-		status = acpi_os_queue_for_execution(OSD_PRIORITY_GPE,
+		status = acpi_os_execute(OSL_EC_BURST_HANDLER,
 						     acpi_ec_gpe_query, ec);
 		return status == AE_OK ?
 		    ACPI_INTERRUPT_HANDLED : ACPI_INTERRUPT_NOT_HANDLED;

drivers/acpi/osl.c

@@ -37,6 +37,7 @@
 #include <linux/delay.h>
 #include <linux/workqueue.h>
 #include <linux/nmi.h>
+#include <linux/kthread.h>
 #include <acpi/acpi.h>
 #include <asm/io.h>
 #include <acpi/acpi_bus.h>
@@ -600,23 +601,41 @@ static void acpi_os_execute_deferred(void *context)
 	return_VOID;
 }
 
-acpi_status
-acpi_os_queue_for_execution(u32 priority,
+static int acpi_os_execute_thread(void *context)
+{
+	struct acpi_os_dpc *dpc = (struct acpi_os_dpc *)context;
+	if (dpc) {
+		dpc->function(dpc->context);
+		kfree(dpc);
+	}
+	do_exit(0);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_os_execute
+ *
+ * PARAMETERS:  Type               - Type of the callback
+ *              Function           - Function to be executed
+ *              Context            - Function parameters
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Depending on type, either queues function for deferred execution or
+ *              immediately executes function on a separate thread.
+ *
+ ******************************************************************************/
+
+acpi_status acpi_os_execute(acpi_execute_type type,
 			    acpi_osd_exec_callback function, void *context)
 {
 	acpi_status status = AE_OK;
 	struct acpi_os_dpc *dpc;
 	struct work_struct *task;
-
-	ACPI_FUNCTION_TRACE("os_queue_for_execution");
-
-	ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
-			  "Scheduling function [%p(%p)] for deferred execution.\n",
-			  function, context));
+	struct task_struct *p;
 
 	if (!function)
-		return_ACPI_STATUS(AE_BAD_PARAMETER);
-
+		return AE_BAD_PARAMETER;
 	/*
 	 * Allocate/initialize DPC structure.  Note that this memory will be
 	 * freed by the callee.  The kernel handles the tq_struct list  in a
@@ -627,30 +646,37 @@ acpi_os_queue_for_execution(u32 priority,
 	 * We can save time and code by allocating the DPC and tq_structs
 	 * from the same memory.
 	 */
-
-	dpc =
-	    kmalloc(sizeof(struct acpi_os_dpc) + sizeof(struct work_struct),
-		    GFP_ATOMIC);
+	if (type == OSL_NOTIFY_HANDLER) {
+		dpc = kmalloc(sizeof(struct acpi_os_dpc), GFP_KERNEL);
+	} else {
+		dpc = kmalloc(sizeof(struct acpi_os_dpc) +
+				sizeof(struct work_struct), GFP_ATOMIC);
+	}
 	if (!dpc)
-		return_ACPI_STATUS(AE_NO_MEMORY);
-
+		return AE_NO_MEMORY;
 	dpc->function = function;
 	dpc->context = context;
 
+	if (type == OSL_NOTIFY_HANDLER) {
+		p = kthread_create(acpi_os_execute_thread, dpc, "kacpid_notify");
+		if (!IS_ERR(p)) {
+			wake_up_process(p);
+		} else {
+			status = AE_NO_MEMORY;
+			kfree(dpc);
+		}
+	} else {
 		task = (void *)(dpc + 1);
 		INIT_WORK(task, acpi_os_execute_deferred, (void *)dpc);
-
 		if (!queue_work(kacpid_wq, task)) {
-		ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
-				  "Call to queue_work() failed.\n"));
-		kfree(dpc);
 			status = AE_ERROR;
+			kfree(dpc);
 		}
-
-	return_ACPI_STATUS(status);
+	}
+	return status;
 }
 
-EXPORT_SYMBOL(acpi_os_queue_for_execution);
+EXPORT_SYMBOL(acpi_os_execute);
 
 void acpi_os_wait_events_complete(void *context)
 {

drivers/acpi/thermal.c

@@ -684,8 +684,7 @@ static void acpi_thermal_run(unsigned long data)
 {
 	struct acpi_thermal *tz = (struct acpi_thermal *)data;
 	if (!tz->zombie)
-		acpi_os_queue_for_execution(OSD_PRIORITY_GPE,
-					    acpi_thermal_check, (void *)data);
+		acpi_os_execute(OSL_GPE_HANDLER, acpi_thermal_check, (void *)data);
 }
 
 static void acpi_thermal_check(void *data)