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SubjectRe: 2.5.40-mm2

On Sun, 6 Oct 2002, Dave Hansen wrote:

> cc'ing Ingo, because I think this might be related to the timer bh
> removal.

could you try the attached patch against 2.5.41, does it help? It fixes
the bugs found so far plus makes del_timer_sync() a bit more robust by
re-checking timer pending-ness before exiting. There is one type of code
that might have relied on this kind of behavior of the old timer code.

Ingo

--- linux/kernel/timer.c.orig 2002-10-08 12:39:46.000000000 +0200
+++ linux/kernel/timer.c 2002-10-08 12:49:50.000000000 +0200
@@ -266,29 +266,31 @@
int del_timer_sync(timer_t *timer)
{
tvec_base_t *base = tvec_bases;
- int i, ret;
+ int i, ret = 0;

- ret = del_timer(timer);
+del_again:
+ ret += del_timer(timer);

- for (i = 0; i < NR_CPUS; i++) {
+ for (i = 0; i < NR_CPUS; i++, base++) {
if (!cpu_online(i))
continue;
if (base->running_timer == timer) {
while (base->running_timer == timer) {
cpu_relax();
- preempt_disable();
- preempt_enable();
+ preempt_check_resched();
}
break;
}
- base++;
}
+ if (timer_pending(timer))
+ goto del_again;
+
return ret;
}
#endif


-static void cascade(tvec_base_t *base, tvec_t *tv)
+static int cascade(tvec_base_t *base, tvec_t *tv)
{
/* cascade all the timers from tv up one level */
struct list_head *head, *curr, *next;
@@ -310,7 +312,8 @@
curr = next;
}
INIT_LIST_HEAD(head);
- tv->index = (tv->index + 1) & TVN_MASK;
+
+ return tv->index = (tv->index + 1) & TVN_MASK;
}

/***
@@ -322,26 +325,18 @@
*/
static inline void __run_timers(tvec_base_t *base)
{
- unsigned long flags;
-
- spin_lock_irqsave(&base->lock, flags);
+ spin_lock_irq(&base->lock);
while ((long)(jiffies - base->timer_jiffies) >= 0) {
struct list_head *head, *curr;

/*
* Cascade timers:
*/
- if (!base->tv1.index) {
- cascade(base, &base->tv2);
- if (base->tv2.index == 1) {
- cascade(base, &base->tv3);
- if (base->tv3.index == 1) {
- cascade(base, &base->tv4);
- if (base->tv4.index == 1)
- cascade(base, &base->tv5);
- }
- }
- }
+ if (!base->tv1.index &&
+ (cascade(base, &base->tv2) == 1) &&
+ (cascade(base, &base->tv3) == 1) &&
+ cascade(base, &base->tv4) == 1)
+ cascade(base, &base->tv5);
repeat:
head = base->tv1.vec + base->tv1.index;
curr = head->next;
@@ -370,7 +365,7 @@
#if CONFIG_SMP
base->running_timer = NULL;
#endif
- spin_unlock_irqrestore(&base->lock, flags);
+ spin_unlock_irq(&base->lock);
}

/******************************************************************/
-
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