Re: [RFC] New Improved Stronger Whiter Timers (was: Kernel Janitor)

[Daniel Phillips]

On Tue, 30 Jan 2001, Manfred Spraul wrote:
> This one is an UP and SMP race:
> 
>   spin_unlock_irq(&timerlist_lock); 
> + if (timer->event) 
> + { 
> + if ((requeue = timer->event(data))) 
> + { 
> + timer->expires += requeue; 
> + internal_add_timer(timer); 
> + } 
> + } 
> + else 
> + timer->function(data); /* bad old way */ 
>   spin_lock_irq(&timerlist_lock); 
> 
> internal_add_timer assumes that the timerlist_lock is acquired.

Yes, oops, here is the fix.

--- ../2.4.1.clean/include/linux/timer.h        Tue Jan 30 08:24:55 2001
+++ ./include/linux/timer.h     Tue Jan 30 21:52:58 2001
@@ -22,6 +22,7 @@
        unsigned long expires;
        unsigned long data;
        void (*function)(unsigned long);
+       unsigned long (*event)(unsigned long data);
 };
 
 extern void add_timer(struct timer_list * timer);
@@ -49,6 +50,9 @@
 static inline void init_timer(struct timer_list * timer)
 {
        timer->list.next = timer->list.prev = NULL;
+       timer->function = NULL;
+       timer->event = NULL;
+       timer->data = 0;
 }
 
 static inline int timer_pending (const struct timer_list * timer)
--- ../2.4.1.clean/kernel/timer.c       Sun Dec 10 18:53:19 2000
+++ ./kernel/timer.c    Tue Jan 30 22:09:09 2001
@@ -301,19 +301,30 @@
                curr = head->next;
                if (curr != head) {
                        struct timer_list *timer;
-                       void (*fn)(unsigned long);
-                       unsigned long data;
+                       unsigned long data, requeue;
 
                        timer = list_entry(curr, struct timer_list, list);
-                       fn = timer->function;
                        data= timer->data;
 
                        detach_timer(timer);
                        timer->list.next = timer->list.prev = NULL;
                        timer_enter(timer);
                        spin_unlock_irq(&timerlist_lock);
-                       fn(data);
-                       spin_lock_irq(&timerlist_lock);
+                       if (timer->event)
+                       {
+                               requeue = timer->event(data);
+                               spin_lock_irq(&timerlist_lock);
+                               if (requeue)
+                               {
+                                       timer->expires += requeue;
+                                       internal_add_timer(timer);
+                               }
+                       }
+                       else
+                       {
+                               timer->function(data); /* bad old way */
+                               spin_lock_irq(&timerlist_lock);
+                       }
                        timer_exit();
                        goto repeat;
                }

-- 
Daniel
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