charger_manager: Don't use [delayed_]work_pending()

There's no need to test whether a (delayed) work item in pending
before queueing, flushing or cancelling it.  Most uses are unnecessary
and quite a few of them are buggy.

Remove unnecessary pending tests and rewrite _setup_polling() so that
it uses mod_delayed_work() if the next polling interval is sooner than
currently scheduled.  queue_delayed_work() is used otherwise.

Only compile tested.  I noticed that two work items - setup_polling
and cm_monitor_work - schedule each other.  It's a very unusual
construct and I'm fairly sure it's racy.  You can't break such
circular dependency by calling cancel on each.  I strongly recommend
revising the mechanism.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Anton Vorontsov <cbou@mail.ru>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Donggeun Kim <dg77.kim@samsung.com>
Cc: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>

diff --git a/drivers/power/charger-manager.c b/drivers/power/charger-manager.c
index 029732d830908c4c3d13a4026b2d5b581a87f8e4..8acc3f8d303c70876e9e53e01a3dffa985cddc44 100644 (file)
--- a/drivers/power/charger-manager.c
+++ b/drivers/power/charger-manager.c
@@ -669,15 +669,21 @@ static void _setup_polling(struct work_struct *work)
        WARN(cm_wq == NULL, "charger-manager: workqueue not initialized"
                            ". try it later. %s\n", __func__);
 
+       /*
+        * Use mod_delayed_work() iff the next polling interval should
+        * occur before the currently scheduled one.  If @cm_monitor_work
+        * isn't active, the end result is the same, so no need to worry
+        * about stale @next_polling.
+        */
        _next_polling = jiffies + polling_jiffy;
 
-       if (!delayed_work_pending(&cm_monitor_work) ||
-           (delayed_work_pending(&cm_monitor_work) &&
-            time_after(next_polling, _next_polling))) {
-               next_polling = jiffies + polling_jiffy;
+       if (time_before(_next_polling, next_polling)) {
                mod_delayed_work(cm_wq, &cm_monitor_work, polling_jiffy);
+               next_polling = _next_polling;
+       } else {
+               if (queue_delayed_work(cm_wq, &cm_monitor_work, polling_jiffy))
+                       next_polling = _next_polling;
        }
-
 out:
        mutex_unlock(&cm_list_mtx);
 }
@@ -751,8 +757,7 @@ static void misc_event_handler(struct charger_manager *cm,
        if (cm_suspended)
                device_set_wakeup_capable(cm->dev, true);
 
-       if (!delayed_work_pending(&cm_monitor_work) &&
-           is_polling_required(cm) && cm->desc->polling_interval_ms)
+       if (is_polling_required(cm) && cm->desc->polling_interval_ms)
                schedule_work(&setup_polling);
        uevent_notify(cm, default_event_names[type]);
 }
@@ -1170,8 +1175,7 @@ static int charger_extcon_notifier(struct notifier_block *self,
         * when charger cable is attached.
         */
        if (cable->attached && is_polling_required(cable->cm)) {
-               if (work_pending(&setup_polling))
-                       cancel_work_sync(&setup_polling);
+               cancel_work_sync(&setup_polling);
                schedule_work(&setup_polling);
        }
 
@@ -1718,10 +1722,8 @@ static int charger_manager_remove(struct platform_device *pdev)
        list_del(&cm->entry);
        mutex_unlock(&cm_list_mtx);
 
-       if (work_pending(&setup_polling))
-               cancel_work_sync(&setup_polling);
-       if (delayed_work_pending(&cm_monitor_work))
-               cancel_delayed_work_sync(&cm_monitor_work);
+       cancel_work_sync(&setup_polling);
+       cancel_delayed_work_sync(&cm_monitor_work);
 
        for (i = 0 ; i < desc->num_charger_regulators ; i++) {
                struct charger_regulator *charger
@@ -1790,8 +1792,7 @@ static int cm_suspend_prepare(struct device *dev)
                cm_suspended = true;
        }
 
-       if (delayed_work_pending(&cm->fullbatt_vchk_work))
-               cancel_delayed_work(&cm->fullbatt_vchk_work);
+       cancel_delayed_work(&cm->fullbatt_vchk_work);
        cm->status_save_ext_pwr_inserted = is_ext_pwr_online(cm);
        cm->status_save_batt = is_batt_present(cm);