timer: Implement TIMER_IRQSAFE

[karo-tx-linux.git] / kernel / timer.c

diff --git a/kernel/timer.c b/kernel/timer.c
index 8d185a1677ccfd6c5275e9636ab34a2015db9ade..706fe4c53e82ba953ea6c54f4cd22c8ef03781cb 100644 (file)
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -95,6 +95,11 @@ static inline unsigned int tbase_get_deferrable(struct tvec_base *base)
        return ((unsigned int)(unsigned long)base & TIMER_DEFERRABLE);
 }
 
+static inline unsigned int tbase_get_irqsafe(struct tvec_base *base)
+{
+       return ((unsigned int)(unsigned long)base & TIMER_IRQSAFE);
+}
+
 static inline struct tvec_base *tbase_get_base(struct tvec_base *base)
 {
        return ((struct tvec_base *)((unsigned long)base & ~TIMER_FLAG_MASK));
@@ -1002,14 +1007,14 @@ EXPORT_SYMBOL(try_to_del_timer_sync);
  *
  * Synchronization rules: Callers must prevent restarting of the timer,
  * otherwise this function is meaningless. It must not be called from
- * interrupt contexts. The caller must not hold locks which would prevent
- * completion of the timer's handler. The timer's handler must not call
- * add_timer_on(). Upon exit the timer is not queued and the handler is
- * not running on any CPU.
+ * interrupt contexts unless the timer is an irqsafe one. The caller must
+ * not hold locks which would prevent completion of the timer's
+ * handler. The timer's handler must not call add_timer_on(). Upon exit the
+ * timer is not queued and the handler is not running on any CPU.
  *
- * Note: You must not hold locks that are held in interrupt context
- *   while calling this function. Even if the lock has nothing to do
- *   with the timer in question.  Here's why:
+ * Note: For !irqsafe timers, you must not hold locks that are held in
+ *   interrupt context while calling this function. Even if the lock has
+ *   nothing to do with the timer in question.  Here's why:
  *
  *    CPU0                             CPU1
  *    ----                             ----
@@ -1046,7 +1051,7 @@ int del_timer_sync(struct timer_list *timer)
         * don't use it in hardirq context, because it
         * could lead to deadlock.
         */
-       WARN_ON(in_irq());
+       WARN_ON(in_irq() && !tbase_get_irqsafe(timer->base));
        for (;;) {
                int ret = try_to_del_timer_sync(timer);
                if (ret >= 0)
@@ -1153,19 +1158,27 @@ static inline void __run_timers(struct tvec_base *base)
                while (!list_empty(head)) {
                        void (*fn)(unsigned long);
                        unsigned long data;
+                       bool irqsafe;
 
                        timer = list_first_entry(head, struct timer_list,entry);
                        fn = timer->function;
                        data = timer->data;
+                       irqsafe = tbase_get_irqsafe(timer->base);
 
                        timer_stats_account_timer(timer);
 
                        base->running_timer = timer;
                        detach_expired_timer(timer, base);
 
-                       spin_unlock_irq(&base->lock);
-                       call_timer_fn(timer, fn, data);
-                       spin_lock_irq(&base->lock);
+                       if (irqsafe) {
+                               spin_unlock(&base->lock);
+                               call_timer_fn(timer, fn, data);
+                               spin_lock(&base->lock);
+                       } else {
+                               spin_unlock_irq(&base->lock);
+                               call_timer_fn(timer, fn, data);
+                               spin_lock_irq(&base->lock);
+                       }
                }
        }
        base->running_timer = NULL;