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>

1 files changed, 16 insertions, 15 deletions

diff --git a/drivers/power/charger-manager.c b/drivers/power/charger-manager.c
index 029732d83090..8acc3f8d303c 100644
--- 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);