2 files changed, 100 insertions, 28 deletions

diff --git a/drivers/edac/edac_device.c b/drivers/edac/edac_device.c
index 173f4ba0f7c8..7e3723768aca 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);
 
diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index 2d53cb38868a..4471be362599 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -258,6 +258,12 @@ static void edac_mc_workq_function(struct work_struct *work_req)
 
         mutex_lock(&mem_ctls_mutex);
 
+        /* if this control struct has movd to offline state, we are done */
+        if (mci->op_state == OP_OFFLINE) {
+                mutex_unlock(&mem_ctls_mutex);
+                return;
+        }
+
         /* Only poll controllers that are running polled and have a check */
         if (edac_mc_assert_error_check_and_clear() && (mci->edac_check != NULL))
                 mci->edac_check(mci);
@@ -279,11 +285,19 @@ static void edac_mc_workq_function(struct work_struct *work_req)
  * edac_mc_workq_setup
  *      initialize a workq item for this mci
  *      passing in the new delay period in msec
+ *
+ *      locking model:
+ *
+ *              called with the mem_ctls_mutex held
  */
-void edac_mc_workq_setup(struct mem_ctl_info *mci, unsigned msec)
+static void edac_mc_workq_setup(struct mem_ctl_info *mci, unsigned msec)
 {
         debugf0("%s()\n", __func__);
 
+        /* if this instance is not in the POLL state, then simply return */
+        if (mci->op_state != OP_RUNNING_POLL)
+                return;
+
         INIT_DELAYED_WORK(&mci->work, edac_mc_workq_function);
         queue_delayed_work(edac_workqueue, &mci->work, msecs_to_jiffies(msec));
 }
@@ -291,29 +305,39 @@ void edac_mc_workq_setup(struct mem_ctl_info *mci, unsigned msec)
 /*
  * edac_mc_workq_teardown
  *      stop the workq processing on this mci
+ *
+ *      locking model:
+ *
+ *              called WITHOUT lock held
  */
-void edac_mc_workq_teardown(struct mem_ctl_info *mci)
+static void edac_mc_workq_teardown(struct mem_ctl_info *mci)
 {
         int status;
 
-        status = cancel_delayed_work(&mci->work);
-        if (status == 0) {
-                /* workq instance might be running, wait for it */
-                flush_workqueue(edac_workqueue);
+        /* if not running POLL, leave now */
+        if (mci->op_state == OP_RUNNING_POLL) {
+                status = cancel_delayed_work(&mci->work);
+                if (status == 0) {
+                        debugf0("%s() not canceled, flush the queue\n",
+                                __func__);
+
+                        /* workq instance might be running, wait for it */
+                        flush_workqueue(edac_workqueue);
+                }
         }
 }
 
 /*
  * edac_reset_delay_period
  */
-
-void edac_reset_delay_period(struct mem_ctl_info *mci, unsigned long value)
+static void edac_reset_delay_period(struct mem_ctl_info *mci, unsigned long value)
 {
-        mutex_lock(&mem_ctls_mutex);
-
         /* cancel the current workq request */
         edac_mc_workq_teardown(mci);
 
+        /* lock the list of devices for the new setup */
+        mutex_lock(&mem_ctls_mutex);
+
         /* restart the workq request, with new delay value */
         edac_mc_workq_setup(mci, value);
 
@@ -323,6 +347,10 @@ void edac_reset_delay_period(struct mem_ctl_info *mci, unsigned long value)
 /* Return 0 on success, 1 on failure.
  * Before calling this function, caller must
  * assign a unique value to mci->mc_idx.
+ *
+ *      locking model:
+ *
+ *              called with the mem_ctls_mutex lock held
  */
 static int add_mc_to_global_list(struct mem_ctl_info *mci)
 {
@@ -331,7 +359,8 @@ static int add_mc_to_global_list(struct mem_ctl_info *mci)
 
         insert_before = &mc_devices;
 
-        if (unlikely((p = find_mci_by_dev(mci->dev)) != NULL))
+        p = find_mci_by_dev(mci->dev);
+        if (unlikely(p != NULL))
                 goto fail0;
 
         list_for_each(item, &mc_devices) {
@@ -467,8 +496,8 @@ int edac_mc_add_mc(struct mem_ctl_info *mci)
         }
 
         /* Report action taken */
-        edac_mc_printk(mci, KERN_INFO, "Giving out device to %s %s: DEV %s\n",
-                mci->mod_name, mci->ctl_name, dev_name(mci));
+        edac_mc_printk(mci, KERN_INFO, "Giving out device to '%s' '%s':"
+                " DEV %s\n", mci->mod_name, mci->ctl_name, dev_name(mci));
 
         mutex_unlock(&mem_ctls_mutex);
         return 0;
@@ -493,10 +522,13 @@ struct mem_ctl_info *edac_mc_del_mc(struct device *dev)
 {
         struct mem_ctl_info *mci;
 
-        debugf0("MC: %s()\n", __func__);
+        debugf0("%s()\n", __func__);
+
         mutex_lock(&mem_ctls_mutex);
 
-        if ((mci = find_mci_by_dev(dev)) == NULL) {
+        /* find the requested mci struct in the global list */
+        mci = find_mci_by_dev(dev);
+        if (mci == NULL) {
                 mutex_unlock(&mem_ctls_mutex);
                 return NULL;
         }
@@ -504,15 +536,17 @@ struct mem_ctl_info *edac_mc_del_mc(struct device *dev)
         /* marking MCI offline */
         mci->op_state = OP_OFFLINE;
 
-        /* flush workq processes */
-        edac_mc_workq_teardown(mci);
-
-        edac_remove_sysfs_mci_device(mci);
         del_mc_from_global_list(mci);
         mutex_unlock(&mem_ctls_mutex);
+
+        /* flush workq processes and remove sysfs */
+        edac_mc_workq_teardown(mci);
+        edac_remove_sysfs_mci_device(mci);
+
         edac_printk(KERN_INFO, EDAC_MC,
                 "Removed device %d for %s %s: DEV %s\n", mci->mc_idx,
                 mci->mod_name, mci->ctl_name, dev_name(mci));
+
         return mci;
 }
 EXPORT_SYMBOL_GPL(edac_mc_del_mc);