1 files changed, 47 insertions, 9 deletions

diff --git a/drivers/edac/edac_device.c b/drivers/edac/edac_device.c
index 173f4ba0f7c..7e3723768ac 100644
--- a/drivers/edac/edac_device.c
+++ b/drivers/edac/edac_device.c
@@ -32,7 +32,9 @@
 #include "edac_core.h"
 #include "edac_module.h"
 
-/* lock to memory controller's control array 'edac_device_list' */
+/* lock for the list: 'edac_device_list', manipulation of this list
+ * is protected by the 'device_ctls_mutex' lock
+ */
 static DEFINE_MUTEX(device_ctls_mutex);
 static struct list_head edac_device_list = LIST_HEAD_INIT(edac_device_list);
 
@@ -386,6 +388,14 @@ EXPORT_SYMBOL_GPL(edac_device_find);
 /*
  * edac_device_workq_function
  *	performs the operation scheduled by a workq request
+ *
+ *	this workq is embedded within an edac_device_ctl_info
+ *	structure, that needs to be polled for possible error events.
+ *
+ *	This operation is to acquire the list mutex lock
+ *	(thus preventing insertation or deletion)
+ *	and then call the device's poll function IFF this device is
+ *	running polled and there is a poll function defined.
  */
 static void edac_device_workq_function(struct work_struct *work_req)
 {
@@ -403,8 +413,17 @@ static void edac_device_workq_function(struct work_struct *work_req)
 
 	mutex_unlock(&device_ctls_mutex);
 
-	/* Reschedule */
-	queue_delayed_work(edac_workqueue, &edac_dev->work, edac_dev->delay);
+	/* Reschedule the workq for the next time period to start again
+	 * if the number of msec is for 1 sec, then adjust to the next
+	 * whole one second to save timers fireing all over the period
+	 * between integral seconds
+	 */
+	if (edac_dev->poll_msec == 1000)
+		queue_delayed_work(edac_workqueue, &edac_dev->work,
+				round_jiffies(edac_dev->delay));
+	else
+		queue_delayed_work(edac_workqueue, &edac_dev->work,
+				edac_dev->delay);
 }
 
 /*
@@ -417,11 +436,26 @@ void edac_device_workq_setup(struct edac_device_ctl_info *edac_dev,
 {
 	debugf0("%s()\n", __func__);
 
+	/* take the arg 'msec' and set it into the control structure
+	 * to used in the time period calculation
+	 * then calc the number of jiffies that represents
+	 */
 	edac_dev->poll_msec = msec;
-	edac_dev->delay = msecs_to_jiffies(msec);	/* Calc delay jiffies */
+	edac_dev->delay = msecs_to_jiffies(msec);
 
 	INIT_DELAYED_WORK(&edac_dev->work, edac_device_workq_function);
-	queue_delayed_work(edac_workqueue, &edac_dev->work, edac_dev->delay);
+
+	/* optimize here for the 1 second case, which will be normal value, to
+	 * fire ON the 1 second time event. This helps reduce all sorts of
+	 * timers firing on sub-second basis, while they are happy
+	 * to fire together on the 1 second exactly
+	 */
+	if (edac_dev->poll_msec == 1000)
+		queue_delayed_work(edac_workqueue, &edac_dev->work,
+				round_jiffies(edac_dev->delay));
+	else
+		queue_delayed_work(edac_workqueue, &edac_dev->work,
+				edac_dev->delay);
 }
 
 /*
@@ -441,16 +475,20 @@ void edac_device_workq_teardown(struct edac_device_ctl_info *edac_dev)
 
 /*
  * edac_device_reset_delay_period
+ *
+ *	need to stop any outstanding workq queued up at this time
+ *	because we will be resetting the sleep time.
+ *	Then restart the workq on the new delay
  */
-
 void edac_device_reset_delay_period(struct edac_device_ctl_info *edac_dev,
 					unsigned long value)
 {
-	mutex_lock(&device_ctls_mutex);
-
-	/* cancel the current workq request */
+	/* cancel the current workq request, without the mutex lock */
 	edac_device_workq_teardown(edac_dev);
 
+	/* acquire the mutex before doing the workq setup */
+	mutex_lock(&device_ctls_mutex);
+
 	/* restart the workq request, with new delay value */
 	edac_device_workq_setup(edac_dev, value);