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Commit fefcfd43 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'core-fixes-for-linus' of...

Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  futex: Move drop_futex_key_refs out of spinlock'ed region
  rcu: Fix TREE_PREEMPT_RCU CPU_HOTPLUG bad-luck hang
  rcu: Stopgap fix for synchronize_rcu_expedited() for TREE_PREEMPT_RCU
  rcu: Prevent RCU IPI storms in presence of high call_rcu() load
  futex: Check for NULL keys in match_futex
  futex: Handle spurious wake up
parents 37c2ca24 89061d3d
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+1 −5
Original line number Diff line number Diff line
@@ -76,11 +76,7 @@ static inline void __rcu_read_unlock_bh(void)

extern void call_rcu_sched(struct rcu_head *head,
			   void (*func)(struct rcu_head *rcu));

static inline void synchronize_rcu_expedited(void)
{
	synchronize_sched_expedited();
}
extern void synchronize_rcu_expedited(void);

static inline void synchronize_rcu_bh_expedited(void)
{
+19 −5
Original line number Diff line number Diff line
@@ -150,7 +150,8 @@ static struct futex_hash_bucket *hash_futex(union futex_key *key)
 */
static inline int match_futex(union futex_key *key1, union futex_key *key2)
{
	return (key1->both.word == key2->both.word
	return (key1 && key2
		&& key1->both.word == key2->both.word
		&& key1->both.ptr == key2->both.ptr
		&& key1->both.offset == key2->both.offset);
}
@@ -1028,7 +1029,6 @@ static inline
void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key,
			   struct futex_hash_bucket *hb)
{
	drop_futex_key_refs(&q->key);
	get_futex_key_refs(key);
	q->key = *key;

@@ -1226,6 +1226,7 @@ static int futex_requeue(u32 __user *uaddr1, int fshared, u32 __user *uaddr2,
		 */
		if (ret == 1) {
			WARN_ON(pi_state);
			drop_count++;
			task_count++;
			ret = get_futex_value_locked(&curval2, uaddr2);
			if (!ret)
@@ -1304,6 +1305,7 @@ static int futex_requeue(u32 __user *uaddr1, int fshared, u32 __user *uaddr2,
			if (ret == 1) {
				/* We got the lock. */
				requeue_pi_wake_futex(this, &key2, hb2);
				drop_count++;
				continue;
			} else if (ret) {
				/* -EDEADLK */
@@ -1791,6 +1793,7 @@ 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)
@@ -1808,9 +1811,14 @@ 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;
@@ -2118,9 +2126,11 @@ 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;
@@ -2198,6 +2208,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, int fshared,
	debug_rt_mutex_init_waiter(&rt_waiter);
	rt_waiter.task = NULL;

retry:
	key2 = FUTEX_KEY_INIT;
	ret = get_futex_key(uaddr2, fshared, &key2, VERIFY_WRITE);
	if (unlikely(ret != 0))
@@ -2292,6 +2303,9 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, int fshared,
out_key2:
	put_futex_key(fshared, &key2);

	/* Spurious wakeup ? */
	if (ret == -EAGAIN)
		goto retry;
out:
	if (to) {
		hrtimer_cancel(&to->timer);
+38 −6
Original line number Diff line number Diff line
@@ -913,7 +913,20 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
			spin_unlock(&rnp->lock); /* irqs remain disabled. */
			break;
		}
		rcu_preempt_offline_tasks(rsp, rnp, rdp);

		/*
		 * If there was a task blocking the current grace period,
		 * and if all CPUs have checked in, we need to propagate
		 * the quiescent state up the rcu_node hierarchy.  But that
		 * is inconvenient at the moment due to deadlock issues if
		 * this should end the current grace period.  So set the
		 * offlined CPU's bit in ->qsmask in order to force the
		 * next force_quiescent_state() invocation to clean up this
		 * mess in a deadlock-free manner.
		 */
		if (rcu_preempt_offline_tasks(rsp, rnp, rdp) && !rnp->qsmask)
			rnp->qsmask |= mask;

		mask = rnp->grpmask;
		spin_unlock(&rnp->lock);	/* irqs remain disabled. */
		rnp = rnp->parent;
@@ -958,7 +971,7 @@ static void rcu_offline_cpu(int cpu)
 * Invoke any RCU callbacks that have made it to the end of their grace
 * period.  Thottle as specified by rdp->blimit.
 */
static void rcu_do_batch(struct rcu_data *rdp)
static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
{
	unsigned long flags;
	struct rcu_head *next, *list, **tail;
@@ -1011,6 +1024,13 @@ static void rcu_do_batch(struct rcu_data *rdp)
	if (rdp->blimit == LONG_MAX && rdp->qlen <= qlowmark)
		rdp->blimit = blimit;

	/* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */
	if (rdp->qlen == 0 && rdp->qlen_last_fqs_check != 0) {
		rdp->qlen_last_fqs_check = 0;
		rdp->n_force_qs_snap = rsp->n_force_qs;
	} else if (rdp->qlen < rdp->qlen_last_fqs_check - qhimark)
		rdp->qlen_last_fqs_check = rdp->qlen;

	local_irq_restore(flags);

	/* Re-raise the RCU softirq if there are callbacks remaining. */
@@ -1224,7 +1244,7 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
	}

	/* If there are callbacks ready, invoke them. */
	rcu_do_batch(rdp);
	rcu_do_batch(rsp, rdp);
}

/*
@@ -1288,10 +1308,20 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
		rcu_start_gp(rsp, nestflag);  /* releases rnp_root->lock. */
	}

	/* Force the grace period if too many callbacks or too long waiting. */
	if (unlikely(++rdp->qlen > qhimark)) {
	/*
	 * Force the grace period if too many callbacks or too long waiting.
	 * Enforce hysteresis, and don't invoke force_quiescent_state()
	 * if some other CPU has recently done so.  Also, don't bother
	 * invoking force_quiescent_state() if the newly enqueued callback
	 * is the only one waiting for a grace period to complete.
	 */
	if (unlikely(++rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) {
		rdp->blimit = LONG_MAX;
		if (rsp->n_force_qs == rdp->n_force_qs_snap &&
		    *rdp->nxttail[RCU_DONE_TAIL] != head)
			force_quiescent_state(rsp, 0);
		rdp->n_force_qs_snap = rsp->n_force_qs;
		rdp->qlen_last_fqs_check = rdp->qlen;
	} else if ((long)(ACCESS_ONCE(rsp->jiffies_force_qs) - jiffies) < 0)
		force_quiescent_state(rsp, 1);
	local_irq_restore(flags);
@@ -1523,6 +1553,8 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
	rdp->beenonline = 1;	 /* We have now been online. */
	rdp->preemptable = preemptable;
	rdp->passed_quiesc_completed = lastcomp - 1;
	rdp->qlen_last_fqs_check = 0;
	rdp->n_force_qs_snap = rsp->n_force_qs;
	rdp->blimit = blimit;
	spin_unlock(&rnp->lock);		/* irqs remain disabled. */

+7 −3
Original line number Diff line number Diff line
@@ -167,6 +167,10 @@ struct rcu_data {
	struct rcu_head *nxtlist;
	struct rcu_head **nxttail[RCU_NEXT_SIZE];
	long		qlen;		/* # of queued callbacks */
	long		qlen_last_fqs_check;
					/* qlen at last check for QS forcing */
	unsigned long	n_force_qs_snap;
					/* did other CPU force QS recently? */
	long		blimit;		/* Upper limit on a processed batch */

#ifdef CONFIG_NO_HZ
@@ -302,7 +306,7 @@ static void rcu_print_task_stall(struct rcu_node *rnp);
#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
#ifdef CONFIG_HOTPLUG_CPU
static void rcu_preempt_offline_tasks(struct rcu_state *rsp,
static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
				     struct rcu_node *rnp,
				     struct rcu_data *rdp);
static void rcu_preempt_offline_cpu(int cpu);
+38 −8
Original line number Diff line number Diff line
@@ -304,21 +304,25 @@ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp)
 * parent is to remove the need for rcu_read_unlock_special() to
 * make more than two attempts to acquire the target rcu_node's lock.
 *
 * Returns 1 if there was previously a task blocking the current grace
 * period on the specified rcu_node structure.
 *
 * The caller must hold rnp->lock with irqs disabled.
 */
static void rcu_preempt_offline_tasks(struct rcu_state *rsp,
static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
				     struct rcu_node *rnp,
				     struct rcu_data *rdp)
{
	int i;
	struct list_head *lp;
	struct list_head *lp_root;
	int retval = rcu_preempted_readers(rnp);
	struct rcu_node *rnp_root = rcu_get_root(rsp);
	struct task_struct *tp;

	if (rnp == rnp_root) {
		WARN_ONCE(1, "Last CPU thought to be offlined?");
		return;  /* Shouldn't happen: at least one CPU online. */
		return 0;  /* Shouldn't happen: at least one CPU online. */
	}
	WARN_ON_ONCE(rnp != rdp->mynode &&
		     (!list_empty(&rnp->blocked_tasks[0]) ||
@@ -342,6 +346,8 @@ static void rcu_preempt_offline_tasks(struct rcu_state *rsp,
			spin_unlock(&rnp_root->lock); /* irqs remain disabled */
		}
	}

	return retval;
}

/*
@@ -392,6 +398,17 @@ void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
}
EXPORT_SYMBOL_GPL(call_rcu);

/*
 * Wait for an rcu-preempt grace period.  We are supposed to expedite the
 * grace period, but this is the crude slow compatability hack, so just
 * invoke synchronize_rcu().
 */
void synchronize_rcu_expedited(void)
{
	synchronize_rcu();
}
EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);

/*
 * Check to see if there is any immediate preemptable-RCU-related work
 * to be done.
@@ -521,12 +538,15 @@ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp)

/*
 * Because preemptable RCU does not exist, it never needs to migrate
 * tasks that were blocked within RCU read-side critical sections.
 * tasks that were blocked within RCU read-side critical sections, and
 * such non-existent tasks cannot possibly have been blocking the current
 * grace period.
 */
static void rcu_preempt_offline_tasks(struct rcu_state *rsp,
static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
				     struct rcu_node *rnp,
				     struct rcu_data *rdp)
{
	return 0;
}

/*
@@ -564,6 +584,16 @@ void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
}
EXPORT_SYMBOL_GPL(call_rcu);

/*
 * Wait for an rcu-preempt grace period, but make it happen quickly.
 * But because preemptable RCU does not exist, map to rcu-sched.
 */
void synchronize_rcu_expedited(void)
{
	synchronize_sched_expedited();
}
EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);

/*
 * Because preemptable RCU does not exist, it never has any work to do.
 */