Merge branch 'rt/head' into rt/2.6.31

3 files changed, 27 insertions, 77 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 604f84972eb4..a9652601a6d0 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1190,7 +1190,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 #endif
 	INIT_LIST_HEAD(&p->pi_state_list);
 	p->pi_state_cache = NULL;
-	p->futex_wakeup = NULL;
 #endif
 	/*
 	 * sigaltstack should be cleared when sharing the same VM
diff --git a/kernel/futex.c b/kernel/futex.c
index 3dab2f5c9e2a..7c4a6ac9e710 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -713,7 +713,7 @@ retry:
  * The hash bucket lock must be held when this is called.
  * Afterwards, the futex_q must not be accessed.
  */
-static void wake_futex(struct task_struct **wake_list, struct futex_q *q)
+static void wake_futex(struct futex_q *q)
 {
 	struct task_struct *p = q->task;
 
@@ -736,51 +736,8 @@ static void wake_futex(struct task_struct **wake_list, struct futex_q *q)
 	smp_wmb();
 	q->lock_ptr = NULL;
 
-	/*
-	 * Atomically grab the task, if ->futex_wakeup is !0 already it means
-	 * its already queued (either by us or someone else) and will get the
-	 * wakeup due to that.
-	 *
-	 * This cmpxchg() implies a full barrier, which pairs with the write
-	 * barrier implied by the wakeup in wake_futex_list().
-	 */
-	if (cmpxchg(&p->futex_wakeup, 0, p) != 0) {
-		/*
-		 * It was already queued, drop the extra ref and we're done.
-		 */
-		put_task_struct(p);
-		return;
-	}
-
-	/*
-	 * Put the task on our wakeup list by atomically switching it with
-	 * the list head. (XXX its a local list, no possible concurrency,
-	 * this could be written without cmpxchg).
-	 */
-	do {
-		p->futex_wakeup = *wake_list;
-	} while (cmpxchg(wake_list, p->futex_wakeup, p) != p->futex_wakeup);
-}
-
-/*
- * For each task on the list, deliver the pending wakeup and release the
- * task reference obtained in wake_futex().
- */
-static void wake_futex_list(struct task_struct *head)
-{
-	while (head != &init_task) {
-		struct task_struct *next = head->futex_wakeup;
-
-		head->futex_wakeup = NULL;
-		/*
-		 * wake_up_state() implies a wmb() to pair with the queueing
-		 * in wake_futex() so as to not miss wakeups.
-		 */
-		wake_up_state(head, TASK_NORMAL);
-		put_task_struct(head);
-
-		head = next;
-	}
+	wake_up_state(p, TASK_NORMAL);
+	put_task_struct(p);
 }
 
 static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this)
@@ -894,7 +851,6 @@ static int futex_wake(u32 __user *uaddr, int fshared, int nr_wake, u32 bitset)
 	struct futex_q *this, *next;
 	struct plist_head *head;
 	union futex_key key = FUTEX_KEY_INIT;
-	struct task_struct *wake_list = &init_task;
 	int ret;
 
 	if (!bitset)
@@ -919,7 +875,7 @@ static int futex_wake(u32 __user *uaddr, int fshared, int nr_wake, u32 bitset)
 			if (!(this->bitset & bitset))
 				continue;
 
-			wake_futex(&wake_list, this);
+			wake_futex(this);
 			if (++ret >= nr_wake)
 				break;
 		}
@@ -927,8 +883,6 @@ static int futex_wake(u32 __user *uaddr, int fshared, int nr_wake, u32 bitset)
 
 	spin_unlock(&hb->lock);
 	put_futex_key(fshared, &key);
-
-	wake_futex_list(wake_list);
 out:
 	return ret;
 }
@@ -945,7 +899,6 @@ futex_wake_op(u32 __user *uaddr1, int fshared, u32 __user *uaddr2,
 	struct futex_hash_bucket *hb1, *hb2;
 	struct plist_head *head;
 	struct futex_q *this, *next;
-	struct task_struct *wake_list = &init_task;
 	int ret, op_ret;
 
 retry:
@@ -996,7 +949,7 @@ retry_private:
 
 	plist_for_each_entry_safe(this, next, head, list) {
 		if (match_futex (&this->key, &key1)) {
-			wake_futex(&wake_list, this);
+			wake_futex(this);
 			if (++ret >= nr_wake)
 				break;
 		}
@@ -1008,7 +961,7 @@ retry_private:
 		op_ret = 0;
 		plist_for_each_entry_safe(this, next, head, list) {
 			if (match_futex (&this->key, &key2)) {
-				wake_futex(&wake_list, this);
+				wake_futex(this);
 				if (++op_ret >= nr_wake2)
 					break;
 			}
@@ -1021,8 +974,6 @@ out_put_keys:
 	put_futex_key(fshared, &key2);
 out_put_key1:
 	put_futex_key(fshared, &key1);
-
-	wake_futex_list(wake_list);
 out:
 	return ret;
 }
@@ -1177,7 +1128,6 @@ static int futex_requeue(u32 __user *uaddr1, int fshared, u32 __user *uaddr2,
 	struct futex_hash_bucket *hb1, *hb2;
 	struct plist_head *head1;
 	struct futex_q *this, *next;
-	struct task_struct *wake_list = &init_task;
 	u32 curval2;
 
 	if (requeue_pi) {
@@ -1322,7 +1272,7 @@ retry_private:
 		 * woken by futex_unlock_pi().
 		 */
 		if (++task_count <= nr_wake && !requeue_pi) {
-			wake_futex(&wake_list, this);
+			wake_futex(this);
 			continue;
 		}
 
@@ -1368,8 +1318,6 @@ out_put_keys:
 	put_futex_key(fshared, &key2);
 out_put_key1:
 	put_futex_key(fshared, &key1);
-
-	wake_futex_list(wake_list);
 out:
 	if (pi_state != NULL)
 		free_pi_state(pi_state);
@@ -1805,6 +1753,7 @@ static int futex_wait(u32 __user *uaddr, int fshared,
 					     current->timer_slack_ns);
 	}
 
+retry:
 	/* Prepare to wait on uaddr. */
 	ret = futex_wait_setup(uaddr, val, fshared, &q, &hb);
 	if (ret)
@@ -1822,9 +1771,14 @@ static int futex_wait(u32 __user *uaddr, int fshared,
 		goto out_put_key;
 
 	/*
-	 * We expect signal_pending(current), but another thread may
-	 * have handled it for us already.
+	 * We expect signal_pending(current), but we might be the
+	 * victim of a spurious wakeup as well.
 	 */
+	if (!signal_pending(current)) {
+		put_futex_key(fshared, &q.key);
+		goto retry;
+	}
+
 	ret = -ERESTARTSYS;
 	if (!abs_time)
 		goto out_put_key;
@@ -2131,9 +2085,11 @@ int handle_early_requeue_pi_wakeup(struct futex_hash_bucket *hb,
 		 */
 		plist_del(&q->list, &q->list.plist);
 
+		/* Handle spurious wakeups gracefully */
+		ret = -EAGAIN;
 		if (timeout && !timeout->task)
 			ret = -ETIMEDOUT;
-		else
+		else if (signal_pending(current))
 			ret = -ERESTARTNOINTR;
 	}
 	return ret;
@@ -2215,6 +2171,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, int fshared,
 	q.bitset = bitset;
 	q.rt_waiter = &rt_waiter;
 
+retry:
 	key2 = FUTEX_KEY_INIT;
 	ret = get_futex_key(uaddr2, fshared, &key2, VERIFY_WRITE);
 	if (unlikely(ret != 0))
@@ -2307,6 +2264,9 @@ out_put_keys:
 out_key2:
 	put_futex_key(fshared, &key2);
 
+	/* Spurious wakeup ? */
+	if (ret == -EAGAIN)
+		goto retry;
 out:
 	if (to) {
 		hrtimer_cancel(&to->timer);
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 352697636f0a..590049c17dc8 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -1139,9 +1139,7 @@ static const char *softirq_names [] =
   [NET_RX_SOFTIRQ]	= "net-rx",
   [BLOCK_SOFTIRQ]	= "block",
   [TASKLET_SOFTIRQ]	= "tasklet",
-#ifdef CONFIG_HIGH_RES_TIMERS
   [HRTIMER_SOFTIRQ]	= "hrtimer",
-#endif
   [RCU_SOFTIRQ]		= "rcu",
 };
 
@@ -1161,8 +1159,6 @@ static int __cpuinit cpu_callback(struct notifier_block *nfb,
 			per_cpu(ksoftirqd, hotcpu)[i].tsk = NULL;
 		}
 		for (i = 0; i < NR_SOFTIRQS; i++) {
-			if (!softirq_names[i])
-				continue;
 			p = kthread_create(ksoftirqd,
 					   &per_cpu(ksoftirqd, hotcpu)[i],
 					   "sirq-%s/%d", softirq_names[i],
@@ -1179,11 +1175,8 @@ static int __cpuinit cpu_callback(struct notifier_block *nfb,
 	break;
 	case CPU_ONLINE:
 	case CPU_ONLINE_FROZEN:
-		for (i = 0; i < NR_SOFTIRQS; i++) {
-			p = per_cpu(ksoftirqd, hotcpu)[i].tsk;
-			if (p)
-				wake_up_process(p);
-		}
+		for (i = 0; i < NR_SOFTIRQS; i++)
+			wake_up_process(per_cpu(ksoftirqd, hotcpu)[i].tsk);
 		break;
 #ifdef CONFIG_HOTPLUG_CPU
 	case CPU_UP_CANCELED:
@@ -1197,11 +1190,9 @@ static int __cpuinit cpu_callback(struct notifier_block *nfb,
 		for (i = 0; i < NR_SOFTIRQS; i++) {
 			param.sched_priority = MAX_RT_PRIO-1;
 			p = per_cpu(ksoftirqd, hotcpu)[i].tsk;
-			if (p) {
-				sched_setscheduler(p, SCHED_FIFO, &param);
-				per_cpu(ksoftirqd, hotcpu)[i].tsk = NULL;
-				kthread_stop(p);
-			}
+			sched_setscheduler(p, SCHED_FIFO, &param);
+			per_cpu(ksoftirqd, hotcpu)[i].tsk = NULL;
+			kthread_stop(p);
 		}
 		takeover_tasklets(hotcpu);
 		break;