[PATCH] itimer fixes
Fix the recent off-by-one fix in the itimer code:
1. The repeating timer is figured using the requested time
(not +1 as we know where we are in the jiffie).
2. The tests for interval too large are left to the time_val to jiffie code.
Signed-off-by: George Anzinger <george@mvista.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/itimer.c b/kernel/itimer.c
index a72cb0e..7c1b25e 100644
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -112,28 +112,11 @@
return error;
}
-/*
- * Called with P->sighand->siglock held and P->signal->real_timer inactive.
- * If interval is nonzero, arm the timer for interval ticks from now.
- */
-static inline void it_real_arm(struct task_struct *p, unsigned long interval)
-{
- p->signal->it_real_value = interval; /* XXX unnecessary field?? */
- if (interval == 0)
- return;
- if (interval > (unsigned long) LONG_MAX)
- interval = LONG_MAX;
- /* the "+ 1" below makes sure that the timer doesn't go off before
- * the interval requested. This could happen if
- * time requested % (usecs per jiffy) is more than the usecs left
- * in the current jiffy */
- p->signal->real_timer.expires = jiffies + interval + 1;
- add_timer(&p->signal->real_timer);
-}
void it_real_fn(unsigned long __data)
{
struct task_struct * p = (struct task_struct *) __data;
+ unsigned long inc = p->signal->it_real_incr;
send_group_sig_info(SIGALRM, SEND_SIG_PRIV, p);
@@ -141,14 +124,23 @@
* Now restart the timer if necessary. We don't need any locking
* here because do_setitimer makes sure we have finished running
* before it touches anything.
+ * Note, we KNOW we are (or should be) at a jiffie edge here so
+ * we don't need the +1 stuff. Also, we want to use the prior
+ * expire value so as to not "slip" a jiffie if we are late.
+ * Deal with requesting a time prior to "now" here rather than
+ * in add_timer.
*/
- it_real_arm(p, p->signal->it_real_incr);
+ if (!inc)
+ return;
+ while (time_before_eq(p->signal->real_timer.expires, jiffies))
+ p->signal->real_timer.expires += inc;
+ add_timer(&p->signal->real_timer);
}
int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
{
struct task_struct *tsk = current;
- unsigned long val, interval;
+ unsigned long val, interval, expires;
cputime_t cval, cinterval, nval, ninterval;
switch (which) {
@@ -164,7 +156,10 @@
}
tsk->signal->it_real_incr =
timeval_to_jiffies(&value->it_interval);
- it_real_arm(tsk, timeval_to_jiffies(&value->it_value));
+ expires = timeval_to_jiffies(&value->it_value);
+ if (expires)
+ mod_timer(&tsk->signal->real_timer,
+ jiffies + 1 + expires);
spin_unlock_irq(&tsk->sighand->siglock);
if (ovalue) {
jiffies_to_timeval(val, &ovalue->it_value);
