X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=kernel%2Fposix-cpu-timers.c;h=383ba22f0b627613582807ff4051b7f35559dd10;hb=e0f998930eb67c49f2862c58a45262ad0bc03eca;hp=d30b304a33849fd79bee7c66808d76297ce3b0be;hpb=ba9e358fd04190a59e605c2963a15e014139a707;p=linux-2.6

diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index d30b304a33..383ba22f0b 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -91,7 +91,7 @@ static inline union cpu_time_count cpu_time_sub(clockid_t which_clock,
  * Update expiry time from increment, and increase overrun count,
  * given the current clock sample.
  */
-static inline void bump_cpu_timer(struct k_itimer *timer,
+static void bump_cpu_timer(struct k_itimer *timer,
 				  union cpu_time_count now)
 {
 	int i;
@@ -110,7 +110,7 @@ static inline void bump_cpu_timer(struct k_itimer *timer,
 		for (i = 0; incr < delta - incr; i++)
 			incr = incr << 1;
 		for (; i >= 0; incr >>= 1, i--) {
-			if (delta <= incr)
+			if (delta < incr)
 				continue;
 			timer->it.cpu.expires.sched += incr;
 			timer->it_overrun += 1 << i;
@@ -128,7 +128,7 @@ static inline void bump_cpu_timer(struct k_itimer *timer,
 		for (i = 0; cputime_lt(incr, cputime_sub(delta, incr)); i++)
 			     incr = cputime_add(incr, incr);
 		for (; i >= 0; incr = cputime_halve(incr), i--) {
-			if (cputime_le(delta, incr))
+			if (cputime_lt(delta, incr))
 				continue;
 			timer->it.cpu.expires.cpu =
 				cputime_add(timer->it.cpu.expires.cpu, incr);
@@ -380,14 +380,9 @@ int posix_cpu_timer_create(struct k_itimer *new_timer)
 int posix_cpu_timer_del(struct k_itimer *timer)
 {
 	struct task_struct *p = timer->it.cpu.task;
+	int ret = 0;
 
-	if (timer->it.cpu.firing)
-		return TIMER_RETRY;
-
-	if (unlikely(p == NULL))
-		return 0;
-
-	if (!list_empty(&timer->it.cpu.entry)) {
+	if (likely(p != NULL)) {
 		read_lock(&tasklist_lock);
 		if (unlikely(p->signal == NULL)) {
 			/*
@@ -396,18 +391,20 @@ int posix_cpu_timer_del(struct k_itimer *timer)
 			 */
 			BUG_ON(!list_empty(&timer->it.cpu.entry));
 		} else {
-			/*
-			 * Take us off the task's timer list.
-			 */
 			spin_lock(&p->sighand->siglock);
-			list_del(&timer->it.cpu.entry);
+			if (timer->it.cpu.firing)
+				ret = TIMER_RETRY;
+			else
+				list_del(&timer->it.cpu.entry);
 			spin_unlock(&p->sighand->siglock);
 		}
 		read_unlock(&tasklist_lock);
+
+		if (!ret)
+			put_task_struct(p);
 	}
-	put_task_struct(p);
 
-	return 0;
+	return ret;
 }
 
 /*
@@ -424,8 +421,6 @@ static void cleanup_timers(struct list_head *head,
 	cputime_t ptime = cputime_add(utime, stime);
 
 	list_for_each_entry_safe(timer, next, head, entry) {
-		put_task_struct(timer->task);
-		timer->task = NULL;
 		list_del_init(&timer->entry);
 		if (cputime_lt(timer->expires.cpu, ptime)) {
 			timer->expires.cpu = cputime_zero;
@@ -437,8 +432,6 @@ static void cleanup_timers(struct list_head *head,
 
 	++head;
 	list_for_each_entry_safe(timer, next, head, entry) {
-		put_task_struct(timer->task);
-		timer->task = NULL;
 		list_del_init(&timer->entry);
 		if (cputime_lt(timer->expires.cpu, utime)) {
 			timer->expires.cpu = cputime_zero;
@@ -450,8 +443,6 @@ static void cleanup_timers(struct list_head *head,
 
 	++head;
 	list_for_each_entry_safe(timer, next, head, entry) {
-		put_task_struct(timer->task);
-		timer->task = NULL;
 		list_del_init(&timer->entry);
 		if (timer->expires.sched < sched_time) {
 			timer->expires.sched = 0;
@@ -495,6 +486,9 @@ static void process_timer_rebalance(struct task_struct *p,
  	struct task_struct *t = p;
 	unsigned int nthreads = atomic_read(&p->signal->live);
 
+	if (!nthreads)
+		return;
+
 	switch (clock_idx) {
 	default:
 		BUG();
@@ -582,17 +576,15 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
 	listpos = head;
 	if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
 		list_for_each_entry(next, head, entry) {
-			if (next->expires.sched > nt->expires.sched) {
-				listpos = &next->entry;
+			if (next->expires.sched > nt->expires.sched)
 				break;
-			}
+			listpos = &next->entry;
 		}
 	} else {
 		list_for_each_entry(next, head, entry) {
-			if (cputime_gt(next->expires.cpu, nt->expires.cpu)) {
-				listpos = &next->entry;
+			if (cputime_gt(next->expires.cpu, nt->expires.cpu))
 				break;
-			}
+			listpos = &next->entry;
 		}
 	}
 	list_add(&nt->entry, listpos);
@@ -736,9 +728,15 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
 	 * Disarm any old timer after extracting its expiry time.
 	 */
 	BUG_ON(!irqs_disabled());
+
+	ret = 0;
 	spin_lock(&p->sighand->siglock);
 	old_expires = timer->it.cpu.expires;
-	list_del_init(&timer->it.cpu.entry);
+	if (unlikely(timer->it.cpu.firing)) {
+		timer->it.cpu.firing = -1;
+		ret = TIMER_RETRY;
+	} else
+		list_del_init(&timer->it.cpu.entry);
 	spin_unlock(&p->sighand->siglock);
 
 	/*
@@ -786,7 +784,7 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
 		}
 	}
 
-	if (unlikely(timer->it.cpu.firing)) {
+	if (unlikely(ret)) {
 		/*
 		 * We are colliding with the timer actually firing.
 		 * Punt after filling in the timer's old value, and
@@ -794,8 +792,6 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
 		 * it as an overrun (thanks to bump_cpu_timer above).
 		 */
 		read_unlock(&tasklist_lock);
-		timer->it.cpu.firing = -1;
-		ret = TIMER_RETRY;
 		goto out;
 	}
 
@@ -1169,6 +1165,9 @@ static void check_process_timers(struct task_struct *tsk,
 		unsigned long long sched_left, sched;
 		const unsigned int nthreads = atomic_read(&sig->live);
 
+		if (!nthreads)
+			return;
+
 		prof_left = cputime_sub(prof_expires, utime);
 		prof_left = cputime_sub(prof_left, stime);
 		prof_left = cputime_div(prof_left, nthreads);
@@ -1294,30 +1293,30 @@ void run_posix_cpu_timers(struct task_struct *tsk)
 
 #undef	UNEXPIRED
 
-	BUG_ON(tsk->exit_state);
-
 	/*
 	 * Double-check with locks held.
 	 */
 	read_lock(&tasklist_lock);
-	spin_lock(&tsk->sighand->siglock);
+	if (likely(tsk->signal != NULL)) {
+		spin_lock(&tsk->sighand->siglock);
 
-	/*
-	 * Here we take off tsk->cpu_timers[N] and tsk->signal->cpu_timers[N]
-	 * all the timers that are firing, and put them on the firing list.
-	 */
-	check_thread_timers(tsk, &firing);
-	check_process_timers(tsk, &firing);
+		/*
+		 * Here we take off tsk->cpu_timers[N] and tsk->signal->cpu_timers[N]
+		 * all the timers that are firing, and put them on the firing list.
+		 */
+		check_thread_timers(tsk, &firing);
+		check_process_timers(tsk, &firing);
 
-	/*
-	 * We must release these locks before taking any timer's lock.
-	 * There is a potential race with timer deletion here, as the
-	 * siglock now protects our private firing list.  We have set
-	 * the firing flag in each timer, so that a deletion attempt
-	 * that gets the timer lock before we do will give it up and
-	 * spin until we've taken care of that timer below.
-	 */
-	spin_unlock(&tsk->sighand->siglock);
+		/*
+		 * We must release these locks before taking any timer's lock.
+		 * There is a potential race with timer deletion here, as the
+		 * siglock now protects our private firing list.  We have set
+		 * the firing flag in each timer, so that a deletion attempt
+		 * that gets the timer lock before we do will give it up and
+		 * spin until we've taken care of that timer below.
+		 */
+		spin_unlock(&tsk->sighand->siglock);
+	}
 	read_unlock(&tasklist_lock);
 
 	/*