EDAC: Correct workqueue setup path

commit cb6ef42e upstream.

We're using edac_mc_workq_setup() both on the init path, when
we load an edac driver and when we change the polling period
(edac_mc_reset_delay_period) through /sys/.../edac_mc_poll_msec.

On that second path we don't need to init the workqueue which has been
initialized already.

Thanks to Tejun for workqueue insights.
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1391457913-881-1-git-send-email-prarit@redhat.com
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/edac/edac_mc.c

@@ -323,7 +323,8 @@ static void edac_mc_workq_function(struct work_struct *work_req)
  *
  *		called with the mem_ctls_mutex held
  */
-static 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,
+				bool init)
 {
 	debugf0("%s()\n", __func__);
 
@@ -331,7 +332,9 @@ static void edac_mc_workq_setup(struct mem_ctl_info *mci, unsigned msec)
 	if (mci->op_state != OP_RUNNING_POLL)
 		return;
 
+	if (init)
 		INIT_DELAYED_WORK(&mci->work, edac_mc_workq_function);
+
 	queue_delayed_work(edac_workqueue, &mci->work, msecs_to_jiffies(msec));
 }
 
@@ -391,7 +394,7 @@ void edac_mc_reset_delay_period(int value)
 	list_for_each(item, &mc_devices) {
 		mci = list_entry(item, struct mem_ctl_info, link);
 
-		edac_mc_workq_setup(mci, (unsigned long) value);
+		edac_mc_workq_setup(mci, value, false);
 	}
 
 	mutex_unlock(&mem_ctls_mutex);
@@ -539,7 +542,7 @@ int edac_mc_add_mc(struct mem_ctl_info *mci)
 		/* This instance is NOW RUNNING */
 		mci->op_state = OP_RUNNING_POLL;
 
-		edac_mc_workq_setup(mci, edac_mc_get_poll_msec());
+		edac_mc_workq_setup(mci, edac_mc_get_poll_msec(), true);
 	} else {
 		mci->op_state = OP_RUNNING_INTERRUPT;
 	}