[PATCH] hrtimer: switch itimers to hrtimer
switch itimers to a hrtimers-based implementation
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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 7c1b25e..c2c05c4 100644
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -12,36 +12,46 @@
#include <linux/syscalls.h>
#include <linux/time.h>
#include <linux/posix-timers.h>
+#include <linux/hrtimer.h>
#include <asm/uaccess.h>
-static unsigned long it_real_value(struct signal_struct *sig)
+/**
+ * itimer_get_remtime - get remaining time for the timer
+ *
+ * @timer: the timer to read
+ *
+ * Returns the delta between the expiry time and now, which can be
+ * less than zero or 1usec for an pending expired timer
+ */
+static struct timeval itimer_get_remtime(struct hrtimer *timer)
{
- unsigned long val = 0;
- if (timer_pending(&sig->real_timer)) {
- val = sig->real_timer.expires - jiffies;
+ ktime_t rem = hrtimer_get_remaining(timer);
- /* look out for negative/zero itimer.. */
- if ((long) val <= 0)
- val = 1;
- }
- return val;
+ /*
+ * Racy but safe: if the itimer expires after the above
+ * hrtimer_get_remtime() call but before this condition
+ * then we return 0 - which is correct.
+ */
+ if (hrtimer_active(timer)) {
+ if (rem.tv64 <= 0)
+ rem.tv64 = NSEC_PER_USEC;
+ } else
+ rem.tv64 = 0;
+
+ return ktime_to_timeval(rem);
}
int do_getitimer(int which, struct itimerval *value)
{
struct task_struct *tsk = current;
- unsigned long interval, val;
cputime_t cinterval, cval;
switch (which) {
case ITIMER_REAL:
- spin_lock_irq(&tsk->sighand->siglock);
- interval = tsk->signal->it_real_incr;
- val = it_real_value(tsk->signal);
- spin_unlock_irq(&tsk->sighand->siglock);
- jiffies_to_timeval(val, &value->it_value);
- jiffies_to_timeval(interval, &value->it_interval);
+ value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
+ value->it_interval =
+ ktime_to_timeval(tsk->signal->it_real_incr);
break;
case ITIMER_VIRTUAL:
read_lock(&tasklist_lock);
@@ -113,59 +123,45 @@
}
-void it_real_fn(unsigned long __data)
+/*
+ * The timer is automagically restarted, when interval != 0
+ */
+int it_real_fn(void *data)
{
- struct task_struct * p = (struct task_struct *) __data;
- unsigned long inc = p->signal->it_real_incr;
+ struct task_struct *tsk = (struct task_struct *) data;
- send_group_sig_info(SIGALRM, SEND_SIG_PRIV, p);
+ send_group_sig_info(SIGALRM, SEND_SIG_PRIV, tsk);
- /*
- * 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.
- */
- 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);
+ if (tsk->signal->it_real_incr.tv64 != 0) {
+ hrtimer_forward(&tsk->signal->real_timer,
+ tsk->signal->it_real_incr);
+
+ return HRTIMER_RESTART;
+ }
+ return HRTIMER_NORESTART;
}
int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
{
struct task_struct *tsk = current;
- unsigned long val, interval, expires;
+ struct hrtimer *timer;
+ ktime_t expires;
cputime_t cval, cinterval, nval, ninterval;
switch (which) {
case ITIMER_REAL:
-again:
- spin_lock_irq(&tsk->sighand->siglock);
- interval = tsk->signal->it_real_incr;
- val = it_real_value(tsk->signal);
- /* We are sharing ->siglock with it_real_fn() */
- if (try_to_del_timer_sync(&tsk->signal->real_timer) < 0) {
- spin_unlock_irq(&tsk->sighand->siglock);
- goto again;
+ timer = &tsk->signal->real_timer;
+ hrtimer_cancel(timer);
+ if (ovalue) {
+ ovalue->it_value = itimer_get_remtime(timer);
+ ovalue->it_interval
+ = ktime_to_timeval(tsk->signal->it_real_incr);
}
tsk->signal->it_real_incr =
- timeval_to_jiffies(&value->it_interval);
- 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);
- jiffies_to_timeval(interval,
- &ovalue->it_interval);
- }
+ timeval_to_ktime(value->it_interval);
+ expires = timeval_to_ktime(value->it_value);
+ if (expires.tv64 != 0)
+ hrtimer_start(timer, expires, HRTIMER_REL);
break;
case ITIMER_VIRTUAL:
nval = timeval_to_cputime(&value->it_value);
