ACPI: created a dedicated workqueue for notify() execution

From:  Alexey Starikovskiy <alexey.y.starikovskiy@linux.intel.com>

Needed to handle while loop in GPE handler of HP notebooks.    
http://bugzilla.kernel.org/show_bug.cgi?id=5534

Yield processor before execution of deferred event queue. Needed to avoid
flooding of Compaq n620c with events.
---

 drivers/acpi/osl.c |   51 +++++++++++++++++++++++++++++++++++----------------
 1 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 068fe4f..169ca04 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -34,6 +34,7 @@ #include <linux/smp_lock.h>
 #include <linux/interrupt.h>
 #include <linux/kmod.h>
 #include <linux/delay.h>
+#include <linux/syscalls.h>
 #include <linux/workqueue.h>
 #include <linux/nmi.h>
 #include <acpi/acpi.h>
@@ -73,6 +74,7 @@ static unsigned int acpi_irq_irq;
 static acpi_osd_handler acpi_irq_handler;
 static void *acpi_irq_context;
 static struct workqueue_struct *kacpid_wq;
+static struct workqueue_struct *kacpi_notify_wq;
 
 acpi_status acpi_os_initialize(void)
 {
@@ -91,8 +93,9 @@ acpi_status acpi_os_initialize1(void)
 		return AE_NULL_ENTRY;
 	}
 	kacpid_wq = create_singlethread_workqueue("kacpid");
+	kacpi_notify_wq = create_singlethread_workqueue("kacpi_notify");
 	BUG_ON(!kacpid_wq);
-
+	BUG_ON(!kacpi_notify_wq);
 	return AE_OK;
 }
 
@@ -104,6 +107,7 @@ acpi_status acpi_os_terminate(void)
 	}
 
 	destroy_workqueue(kacpid_wq);
+	destroy_workqueue(kacpi_notify_wq);
 
 	return AE_OK;
 }
@@ -566,10 +570,23 @@ void acpi_os_derive_pci_id(acpi_handle r
 
 static void acpi_os_execute_deferred(void *context)
 {
-	struct acpi_os_dpc *dpc = NULL;
+	struct acpi_os_dpc *dpc = (struct acpi_os_dpc *)context;
+	if (!dpc) {
+		printk(KERN_ERR PREFIX "Invalid (NULL) context\n");
+		return;
+	}
+
+	sys_sched_yield();
+	dpc->function(dpc->context);
+
+	kfree(dpc);
 
+	return;
+}
 
-	dpc = (struct acpi_os_dpc *)context;
+static void acpi_os_execute_notify(void *context)
+{
+	struct acpi_os_dpc *dpc = (struct acpi_os_dpc *)context;
 	if (!dpc) {
 		printk(KERN_ERR PREFIX "Invalid (NULL) context\n");
 		return;
@@ -604,14 +621,12 @@ acpi_status acpi_os_execute(acpi_execute
 	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));
 
 	if (!function)
-		return_ACPI_STATUS(AE_BAD_PARAMETER);
+		return AE_BAD_PARAMETER;
 
 	/*
 	 * Allocate/initialize DPC structure.  Note that this memory will be
@@ -624,9 +639,8 @@ acpi_status acpi_os_execute(acpi_execute
 	 * from the same memory.
 	 */
 
-	dpc =
-	    kmalloc(sizeof(struct acpi_os_dpc) + sizeof(struct work_struct),
-		    GFP_ATOMIC);
+	dpc = kzalloc(sizeof(struct acpi_os_dpc) +
+			sizeof(struct work_struct), GFP_ATOMIC);
 	if (!dpc)
 		return_ACPI_STATUS(AE_NO_MEMORY);
 
@@ -634,13 +648,18 @@ acpi_status acpi_os_execute(acpi_execute
 	dpc->context = context;
 
 	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;
+	if (type == OSL_NOTIFY_HANDLER) {
+		INIT_WORK(task, acpi_os_execute_notify, (void *)dpc);
+		if (!queue_work(kacpi_notify_wq, task)) {
+			status = AE_ERROR;
+			kfree(dpc);
+		}
+	} else {
+		INIT_WORK(task, acpi_os_execute_deferred, (void *)dpc);
+		if (!queue_work(kacpid_wq, task)) {
+			status = AE_ERROR;
+			kfree(dpc);
+		}
 	}
 
 	return_ACPI_STATUS(status);