[PATCH] pi-futex: rt mutex core

Core functions for the rt-mutex subsystem. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] pi-futex: rt mutex core
Core functions for the rt-mutex subsystem. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Ingo Molnar · Linus Torvalds
1 parent b29739f902
Showing 11 changed files with 1181 additions and 0 deletions Side-by-side Diff
include/linux/init_task.h
include/linux/rtmutex.h
include/linux/sched.h
include/linux/sysctl.h
init/Kconfig
kernel/Makefile
kernel/fork.c
kernel/rtmutex.c
kernel/rtmutex.h
kernel/rtmutex_common.h
kernel/sysctl.c
@@ -124,6 +124,7 @@
 	.cpu_timers	= INIT_CPU_TIMERS(tsk.cpu_timers),		\
 	.fs_excl	= ATOMIC_INIT(0),				\
 	.pi_lock	= SPIN_LOCK_UNLOCKED,				\
+	INIT_RT_MUTEXES(tsk)						\
 }
  
  
+/*
+ * RT Mutexes: blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner:
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *
+ * This file contains the public data structure and API definitions.
+ */
+
+#ifndef __LINUX_RT_MUTEX_H
+#define __LINUX_RT_MUTEX_H
+
+#include <linux/linkage.h>
+#include <linux/plist.h>
+#include <linux/spinlock_types.h>
+
+/*
+ * The rt_mutex structure
+ *
+ * @wait_lock:	spinlock to protect the structure
+ * @wait_list:	pilist head to enqueue waiters in priority order
+ * @owner:	the mutex owner
+ */
+struct rt_mutex {
+	spinlock_t		wait_lock;
+	struct plist_head	wait_list;
+	struct task_struct	*owner;
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+	int			save_state;
+	struct list_head	held_list_entry;
+	unsigned long		acquire_ip;
+	const char 		*name, *file;
+	int			line;
+	void			*magic;
+#endif
+};
+
+struct rt_mutex_waiter;
+struct hrtimer_sleeper;
+
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+# define __DEBUG_RT_MUTEX_INITIALIZER(mutexname) \
+	, .name = #mutexname, .file = __FILE__, .line = __LINE__
+# define rt_mutex_init(mutex)			__rt_mutex_init(mutex, __FUNCTION__)
+ extern void rt_mutex_debug_task_free(struct task_struct *tsk);
+#else
+# define __DEBUG_RT_MUTEX_INITIALIZER(mutexname)
+# define rt_mutex_init(mutex)			__rt_mutex_init(mutex, NULL)
+# define rt_mutex_debug_task_free(t)		do { } while (0)
+#endif
+
+#define __RT_MUTEX_INITIALIZER(mutexname) \
+	{ .wait_lock = SPIN_LOCK_UNLOCKED \
+	, .wait_list = PLIST_HEAD_INIT(mutexname.wait_list, mutexname.wait_lock) \
+	, .owner = NULL \
+	__DEBUG_RT_MUTEX_INITIALIZER(mutexname)}
+
+#define DEFINE_RT_MUTEX(mutexname) \
+	struct rt_mutex mutexname = __RT_MUTEX_INITIALIZER(mutexname)
+
+/***
+ * rt_mutex_is_locked - is the mutex locked
+ * @lock: the mutex to be queried
+ *
+ * Returns 1 if the mutex is locked, 0 if unlocked.
+ */
+static inline int rt_mutex_is_locked(struct rt_mutex *lock)
+{
+	return lock->owner != NULL;
+}
+
+extern void __rt_mutex_init(struct rt_mutex *lock, const char *name);
+extern void rt_mutex_destroy(struct rt_mutex *lock);
+
+extern void rt_mutex_lock(struct rt_mutex *lock);
+extern int rt_mutex_lock_interruptible(struct rt_mutex *lock,
+						int detect_deadlock);
+extern int rt_mutex_timed_lock(struct rt_mutex *lock,
+					struct hrtimer_sleeper *timeout,
+					int detect_deadlock);
+
+extern int rt_mutex_trylock(struct rt_mutex *lock);
+
+extern void rt_mutex_unlock(struct rt_mutex *lock);
+
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+# define INIT_RT_MUTEX_DEBUG(tsk)					\
+	.held_list_head	= LIST_HEAD_INIT(tsk.held_list_head),		\
+	.held_list_lock	= SPIN_LOCK_UNLOCKED
+#else
+# define INIT_RT_MUTEX_DEBUG(tsk)
+#endif
+
+#ifdef CONFIG_RT_MUTEXES
+# define INIT_RT_MUTEXES(tsk)						\
+	.pi_waiters	= PLIST_HEAD_INIT(tsk.pi_waiters, tsk.pi_lock),	\
+	INIT_RT_MUTEX_DEBUG(tsk)
+#else
+# define INIT_RT_MUTEXES(tsk)
+#endif
+
+#endif
@@ -73,6 +73,7 @@
 #include <linux/seccomp.h>
 #include <linux/rcupdate.h>
 #include <linux/futex.h>
+#include <linux/rtmutex.h>
  
 #include <linux/time.h>
 #include <linux/param.h>
@@ -857,6 +858,17 @@
  
 	/* Protection of the PI data structures: */
 	spinlock_t pi_lock;
+
+#ifdef CONFIG_RT_MUTEXES
+	/* PI waiters blocked on a rt_mutex held by this task */
+	struct plist_head pi_waiters;
+	/* Deadlock detection and priority inheritance handling */
+	struct rt_mutex_waiter *pi_blocked_on;
+# ifdef CONFIG_DEBUG_RT_MUTEXES
+	spinlock_t held_list_lock;
+	struct list_head held_list_head;
+# endif
+#endif
  
 #ifdef CONFIG_DEBUG_MUTEXES
 	/* mutex deadlock detection */
@@ -149,6 +149,7 @@
 	KERN_ACPI_VIDEO_FLAGS=71, /* int: flags for setting up video after ACPI sleep */
 	KERN_IA64_UNALIGNED=72, /* int: ia64 unaligned userland trap enable */
 	KERN_COMPAT_LOG=73,	/* int: print compat layer  messages */
+	KERN_MAX_LOCK_DEPTH=74,
 };
  
  
@@ -339,9 +339,14 @@
 	  kernel data structures. This saves memory on small machines,
 	  but may reduce performance.
  
+config RT_MUTEXES
+	boolean
+	select PLIST
+
 config FUTEX
 	bool "Enable futex support" if EMBEDDED
 	default y
+	select RT_MUTEXES
 	help
 	  Disabling this option will cause the kernel to be built without
 	  support for "fast userspace mutexes".  The resulting kernel may not
@@ -16,6 +16,7 @@
 ifeq ($(CONFIG_COMPAT),y)
 obj-$(CONFIG_FUTEX) += futex_compat.o
 endif
+obj-$(CONFIG_RT_MUTEXES) += rtmutex.o
 obj-$(CONFIG_GENERIC_ISA_DMA) += dma.o
 obj-$(CONFIG_SMP) += cpu.o spinlock.o
 obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o
@@ -104,6 +104,7 @@
 void free_task(struct task_struct *tsk)
 {
 	free_thread_info(tsk->thread_info);
+	rt_mutex_debug_task_free(tsk);
 	free_task_struct(tsk);
 }
 EXPORT_SYMBOL(free_task);
@@ -913,6 +914,19 @@
 	return current->pid;
 }
  
+static inline void rt_mutex_init_task(struct task_struct *p)
+{
+#ifdef CONFIG_RT_MUTEXES
+	spin_lock_init(&p->pi_lock);
+	plist_head_init(&p->pi_waiters, &p->pi_lock);
+	p->pi_blocked_on = NULL;
+# ifdef CONFIG_DEBUG_RT_MUTEXES
+	spin_lock_init(&p->held_list_lock);
+	INIT_LIST_HEAD(&p->held_list_head);
+# endif
+#endif
+}
+
 /*
  * This creates a new process as a copy of the old one,
  * but does not actually start it yet.
@@ -1033,6 +1047,8 @@
  	}
 	mpol_fix_fork_child_flag(p);
 #endif
+
+	rt_mutex_init_task(p);
  
 #ifdef CONFIG_DEBUG_MUTEXES
 	p->blocked_on = NULL; /* not blocked yet */
+/*
+ * RT-Mutexes: simple blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner.
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2005-2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *  Copyright (C) 2005 Kihon Technologies Inc., Steven Rostedt
+ *  Copyright (C) 2006 Esben Nielsen
+ */
+#include <linux/spinlock.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/timer.h>
+
+#include "rtmutex_common.h"
+
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+# include "rtmutex-debug.h"
+#else
+# include "rtmutex.h"
+#endif
+
+/*
+ * lock->owner state tracking:
+ *
+ * lock->owner holds the task_struct pointer of the owner. Bit 0 and 1
+ * are used to keep track of the "owner is pending" and "lock has
+ * waiters" state.
+ *
+ * owner	bit1	bit0
+ * NULL		0	0	lock is free (fast acquire possible)
+ * NULL		0	1	invalid state
+ * NULL		1	0	Transitional State*
+ * NULL		1	1	invalid state
+ * taskpointer	0	0	lock is held (fast release possible)
+ * taskpointer	0	1	task is pending owner
+ * taskpointer	1	0	lock is held and has waiters
+ * taskpointer	1	1	task is pending owner and lock has more waiters
+ *
+ * Pending ownership is assigned to the top (highest priority)
+ * waiter of the lock, when the lock is released. The thread is woken
+ * up and can now take the lock. Until the lock is taken (bit 0
+ * cleared) a competing higher priority thread can steal the lock
+ * which puts the woken up thread back on the waiters list.
+ *
+ * The fast atomic compare exchange based acquire and release is only
+ * possible when bit 0 and 1 of lock->owner are 0.
+ *
+ * (*) There's a small time where the owner can be NULL and the
+ * "lock has waiters" bit is set.  This can happen when grabbing the lock.
+ * To prevent a cmpxchg of the owner releasing the lock, we need to set this
+ * bit before looking at the lock, hence the reason this is a transitional
+ * state.
+ */
+
+static void
+rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner,
+		   unsigned long mask)
+{
+	unsigned long val = (unsigned long)owner | mask;
+
+	if (rt_mutex_has_waiters(lock))
+		val |= RT_MUTEX_HAS_WAITERS;
+
+	lock->owner = (struct task_struct *)val;
+}
+
+static inline void clear_rt_mutex_waiters(struct rt_mutex *lock)
+{
+	lock->owner = (struct task_struct *)
+			((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS);
+}
+
+static void fixup_rt_mutex_waiters(struct rt_mutex *lock)
+{
+	if (!rt_mutex_has_waiters(lock))
+		clear_rt_mutex_waiters(lock);
+}
+
+/*
+ * We can speed up the acquire/release, if the architecture
+ * supports cmpxchg and if there's no debugging state to be set up
+ */
+#if defined(__HAVE_ARCH_CMPXCHG) && !defined(CONFIG_DEBUG_RT_MUTEXES)
+# define rt_mutex_cmpxchg(l,c,n)	(cmpxchg(&l->owner, c, n) == c)
+static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
+{
+	unsigned long owner, *p = (unsigned long *) &lock->owner;
+
+	do {
+		owner = *p;
+	} while (cmpxchg(p, owner, owner | RT_MUTEX_HAS_WAITERS) != owner);
+}
+#else
+# define rt_mutex_cmpxchg(l,c,n)	(0)
+static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
+{
+	lock->owner = (struct task_struct *)
+			((unsigned long)lock->owner | RT_MUTEX_HAS_WAITERS);
+}
+#endif
+
+/*
+ * Calculate task priority from the waiter list priority
+ *
+ * Return task->normal_prio when the waiter list is empty or when
+ * the waiter is not allowed to do priority boosting
+ */
+int rt_mutex_getprio(struct task_struct *task)
+{
+	if (likely(!task_has_pi_waiters(task)))
+		return task->normal_prio;
+
+	return min(task_top_pi_waiter(task)->pi_list_entry.prio,
+		   task->normal_prio);
+}
+
+/*
+ * Adjust the priority of a task, after its pi_waiters got modified.
+ *
+ * This can be both boosting and unboosting. task->pi_lock must be held.
+ */
+static void __rt_mutex_adjust_prio(struct task_struct *task)
+{
+	int prio = rt_mutex_getprio(task);
+
+	if (task->prio != prio)
+		rt_mutex_setprio(task, prio);
+}
+
+/*
+ * Adjust task priority (undo boosting). Called from the exit path of
+ * rt_mutex_slowunlock() and rt_mutex_slowlock().
+ *
+ * (Note: We do this outside of the protection of lock->wait_lock to
+ * allow the lock to be taken while or before we readjust the priority
+ * of task. We do not use the spin_xx_mutex() variants here as we are
+ * outside of the debug path.)
+ */
+static void rt_mutex_adjust_prio(struct task_struct *task)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&task->pi_lock, flags);
+	__rt_mutex_adjust_prio(task);
+	spin_unlock_irqrestore(&task->pi_lock, flags);
+}
+
+/*
+ * Max number of times we'll walk the boosting chain:
+ */
+int max_lock_depth = 1024;
+
+/*
+ * Adjust the priority chain. Also used for deadlock detection.
+ * Decreases task's usage by one - may thus free the task.
+ * Returns 0 or -EDEADLK.
+ */
+static int rt_mutex_adjust_prio_chain(task_t *task,
+				      int deadlock_detect,
+				      struct rt_mutex *orig_lock,
+				      struct rt_mutex_waiter *orig_waiter
+				      __IP_DECL__)
+{
+	struct rt_mutex *lock;
+	struct rt_mutex_waiter *waiter, *top_waiter = orig_waiter;
+	int detect_deadlock, ret = 0, depth = 0;
+	unsigned long flags;
+
+	detect_deadlock = debug_rt_mutex_detect_deadlock(orig_waiter,
+							 deadlock_detect);
+
+	/*
+	 * The (de)boosting is a step by step approach with a lot of
+	 * pitfalls. We want this to be preemptible and we want hold a
+	 * maximum of two locks per step. So we have to check
+	 * carefully whether things change under us.
+	 */
+ again:
+	if (++depth > max_lock_depth) {
+		static int prev_max;
+
+		/*
+		 * Print this only once. If the admin changes the limit,
+		 * print a new message when reaching the limit again.
+		 */
+		if (prev_max != max_lock_depth) {
+			prev_max = max_lock_depth;
+			printk(KERN_WARNING "Maximum lock depth %d reached "
+			       "task: %s (%d)\n", max_lock_depth,
+			       current->comm, current->pid);
+		}
+		put_task_struct(task);
+
+		return deadlock_detect ? -EDEADLK : 0;
+	}
+ retry:
+	/*
+	 * Task can not go away as we did a get_task() before !
+	 */
+	spin_lock_irqsave(&task->pi_lock, flags);
+
+	waiter = task->pi_blocked_on;
+	/*
+	 * Check whether the end of the boosting chain has been
+	 * reached or the state of the chain has changed while we
+	 * dropped the locks.
+	 */
+	if (!waiter || !waiter->task)
+		goto out_unlock_pi;
+
+	if (top_waiter && (!task_has_pi_waiters(task) ||
+			   top_waiter != task_top_pi_waiter(task)))
+		goto out_unlock_pi;
+
+	/*
+	 * When deadlock detection is off then we check, if further
+	 * priority adjustment is necessary.
+	 */
+	if (!detect_deadlock && waiter->list_entry.prio == task->prio)
+		goto out_unlock_pi;
+
+	lock = waiter->lock;
+	if (!spin_trylock(&lock->wait_lock)) {
+		spin_unlock_irqrestore(&task->pi_lock, flags);
+		cpu_relax();
+		goto retry;
+	}
+
+	/* Deadlock detection */
+	if (lock == orig_lock || rt_mutex_owner(lock) == current) {
+		debug_rt_mutex_deadlock(deadlock_detect, orig_waiter, lock);
+		spin_unlock(&lock->wait_lock);
+		ret = deadlock_detect ? -EDEADLK : 0;
+		goto out_unlock_pi;
+	}
+
+	top_waiter = rt_mutex_top_waiter(lock);
+
+	/* Requeue the waiter */
+	plist_del(&waiter->list_entry, &lock->wait_list);
+	waiter->list_entry.prio = task->prio;
+	plist_add(&waiter->list_entry, &lock->wait_list);
+
+	/* Release the task */
+	spin_unlock_irqrestore(&task->pi_lock, flags);
+	put_task_struct(task);
+
+	/* Grab the next task */
+	task = rt_mutex_owner(lock);
+	spin_lock_irqsave(&task->pi_lock, flags);
+
+	if (waiter == rt_mutex_top_waiter(lock)) {
+		/* Boost the owner */
+		plist_del(&top_waiter->pi_list_entry, &task->pi_waiters);
+		waiter->pi_list_entry.prio = waiter->list_entry.prio;
+		plist_add(&waiter->pi_list_entry, &task->pi_waiters);
+		__rt_mutex_adjust_prio(task);
+
+	} else if (top_waiter == waiter) {
+		/* Deboost the owner */
+		plist_del(&waiter->pi_list_entry, &task->pi_waiters);
+		waiter = rt_mutex_top_waiter(lock);
+		waiter->pi_list_entry.prio = waiter->list_entry.prio;
+		plist_add(&waiter->pi_list_entry, &task->pi_waiters);
+		__rt_mutex_adjust_prio(task);
+	}
+
+	get_task_struct(task);
+	spin_unlock_irqrestore(&task->pi_lock, flags);
+
+	top_waiter = rt_mutex_top_waiter(lock);
+	spin_unlock(&lock->wait_lock);
+
+	if (!detect_deadlock && waiter != top_waiter)
+		goto out_put_task;
+
+	goto again;
+
+ out_unlock_pi:
+	spin_unlock_irqrestore(&task->pi_lock, flags);
+ out_put_task:
+	put_task_struct(task);
+	return ret;
+}
+
+/*
+ * Optimization: check if we can steal the lock from the
+ * assigned pending owner [which might not have taken the
+ * lock yet]:
+ */
+static inline int try_to_steal_lock(struct rt_mutex *lock)
+{
+	struct task_struct *pendowner = rt_mutex_owner(lock);
+	struct rt_mutex_waiter *next;
+	unsigned long flags;
+
+	if (!rt_mutex_owner_pending(lock))
+		return 0;
+
+	if (pendowner == current)
+		return 1;
+
+	spin_lock_irqsave(&pendowner->pi_lock, flags);
+	if (current->prio >= pendowner->prio) {
+		spin_unlock_irqrestore(&pendowner->pi_lock, flags);
+		return 0;
+	}
+
+	/*
+	 * Check if a waiter is enqueued on the pending owners
+	 * pi_waiters list. Remove it and readjust pending owners
+	 * priority.
+	 */
+	if (likely(!rt_mutex_has_waiters(lock))) {
+		spin_unlock_irqrestore(&pendowner->pi_lock, flags);
+		return 1;
+	}
+
+	/* No chain handling, pending owner is not blocked on anything: */
+	next = rt_mutex_top_waiter(lock);
+	plist_del(&next->pi_list_entry, &pendowner->pi_waiters);
+	__rt_mutex_adjust_prio(pendowner);
+	spin_unlock_irqrestore(&pendowner->pi_lock, flags);
+
+	/*
+	 * We are going to steal the lock and a waiter was
+	 * enqueued on the pending owners pi_waiters queue. So
+	 * we have to enqueue this waiter into
+	 * current->pi_waiters list. This covers the case,
+	 * where current is boosted because it holds another
+	 * lock and gets unboosted because the booster is
+	 * interrupted, so we would delay a waiter with higher
+	 * priority as current->normal_prio.
+	 *
+	 * Note: in the rare case of a SCHED_OTHER task changing
+	 * its priority and thus stealing the lock, next->task
+	 * might be current:
+	 */
+	if (likely(next->task != current)) {
+		spin_lock_irqsave(&current->pi_lock, flags);
+		plist_add(&next->pi_list_entry, &current->pi_waiters);
+		__rt_mutex_adjust_prio(current);
+		spin_unlock_irqrestore(&current->pi_lock, flags);
+	}
+	return 1;
+}
+
+/*
+ * Try to take an rt-mutex
+ *
+ * This fails
+ * - when the lock has a real owner
+ * - when a different pending owner exists and has higher priority than current
+ *
+ * Must be called with lock->wait_lock held.
+ */
+static int try_to_take_rt_mutex(struct rt_mutex *lock __IP_DECL__)
+{
+	/*
+	 * We have to be careful here if the atomic speedups are
+	 * enabled, such that, when
+	 *  - no other waiter is on the lock
+	 *  - the lock has been released since we did the cmpxchg
+	 * the lock can be released or taken while we are doing the
+	 * checks and marking the lock with RT_MUTEX_HAS_WAITERS.
+	 *
+	 * The atomic acquire/release aware variant of
+	 * mark_rt_mutex_waiters uses a cmpxchg loop. After setting
+	 * the WAITERS bit, the atomic release / acquire can not
+	 * happen anymore and lock->wait_lock protects us from the
+	 * non-atomic case.
+	 *
+	 * Note, that this might set lock->owner =
+	 * RT_MUTEX_HAS_WAITERS in the case the lock is not contended
+	 * any more. This is fixed up when we take the ownership.
+	 * This is the transitional state explained at the top of this file.
+	 */
+	mark_rt_mutex_waiters(lock);
+
+	if (rt_mutex_owner(lock) && !try_to_steal_lock(lock))
+		return 0;
+
+	/* We got the lock. */
+	debug_rt_mutex_lock(lock __IP__);
+
+	rt_mutex_set_owner(lock, current, 0);
+
+	rt_mutex_deadlock_account_lock(lock, current);
+
+	return 1;
+}
+
+/*
+ * Task blocks on lock.
+ *
+ * Prepare waiter and propagate pi chain
+ *
+ * This must be called with lock->wait_lock held.
+ */
+static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
+				   struct rt_mutex_waiter *waiter,
+				   int detect_deadlock
+				   __IP_DECL__)
+{
+	struct rt_mutex_waiter *top_waiter = waiter;
+	task_t *owner = rt_mutex_owner(lock);
+	int boost = 0, res;
+	unsigned long flags;
+
+	spin_lock_irqsave(&current->pi_lock, flags);
+	__rt_mutex_adjust_prio(current);
+	waiter->task = current;
+	waiter->lock = lock;
+	plist_node_init(&waiter->list_entry, current->prio);
+	plist_node_init(&waiter->pi_list_entry, current->prio);
+
+	/* Get the top priority waiter on the lock */
+	if (rt_mutex_has_waiters(lock))
+		top_waiter = rt_mutex_top_waiter(lock);
+	plist_add(&waiter->list_entry, &lock->wait_list);
+
+	current->pi_blocked_on = waiter;
+
+	spin_unlock_irqrestore(&current->pi_lock, flags);
+
+	if (waiter == rt_mutex_top_waiter(lock)) {
+		spin_lock_irqsave(&owner->pi_lock, flags);
+		plist_del(&top_waiter->pi_list_entry, &owner->pi_waiters);
+		plist_add(&waiter->pi_list_entry, &owner->pi_waiters);
+
+		__rt_mutex_adjust_prio(owner);
+		if (owner->pi_blocked_on) {
+			boost = 1;
+			get_task_struct(owner);
+		}
+		spin_unlock_irqrestore(&owner->pi_lock, flags);
+	}
+	else if (debug_rt_mutex_detect_deadlock(waiter, detect_deadlock)) {
+		spin_lock_irqsave(&owner->pi_lock, flags);
+		if (owner->pi_blocked_on) {
+			boost = 1;
+			get_task_struct(owner);
+		}
+		spin_unlock_irqrestore(&owner->pi_lock, flags);
+	}
+	if (!boost)
+		return 0;
+
+	spin_unlock(&lock->wait_lock);
+
+	res = rt_mutex_adjust_prio_chain(owner, detect_deadlock, lock,
+					 waiter __IP__);
+
+	spin_lock(&lock->wait_lock);
+
+	return res;
+}
+
+/*
+ * Wake up the next waiter on the lock.
+ *
+ * Remove the top waiter from the current tasks waiter list and from
+ * the lock waiter list. Set it as pending owner. Then wake it up.
+ *
+ * Called with lock->wait_lock held.
+ */
+static void wakeup_next_waiter(struct rt_mutex *lock)
+{
+	struct rt_mutex_waiter *waiter;
+	struct task_struct *pendowner;
+	unsigned long flags;
+
+	spin_lock_irqsave(&current->pi_lock, flags);
+
+	waiter = rt_mutex_top_waiter(lock);
+	plist_del(&waiter->list_entry, &lock->wait_list);
+
+	/*
+	 * Remove it from current->pi_waiters. We do not adjust a
+	 * possible priority boost right now. We execute wakeup in the
+	 * boosted mode and go back to normal after releasing
+	 * lock->wait_lock.
+	 */
+	plist_del(&waiter->pi_list_entry, &current->pi_waiters);
+	pendowner = waiter->task;
+	waiter->task = NULL;
+
+	rt_mutex_set_owner(lock, pendowner, RT_MUTEX_OWNER_PENDING);
+
+	spin_unlock_irqrestore(&current->pi_lock, flags);
+
+	/*
+	 * Clear the pi_blocked_on variable and enqueue a possible
+	 * waiter into the pi_waiters list of the pending owner. This
+	 * prevents that in case the pending owner gets unboosted a
+	 * waiter with higher priority than pending-owner->normal_prio
+	 * is blocked on the unboosted (pending) owner.
+	 */
+	spin_lock_irqsave(&pendowner->pi_lock, flags);
+
+	WARN_ON(!pendowner->pi_blocked_on);
+	WARN_ON(pendowner->pi_blocked_on != waiter);
+	WARN_ON(pendowner->pi_blocked_on->lock != lock);
+
+	pendowner->pi_blocked_on = NULL;
+
+	if (rt_mutex_has_waiters(lock)) {
+		struct rt_mutex_waiter *next;
+
+		next = rt_mutex_top_waiter(lock);
+		plist_add(&next->pi_list_entry, &pendowner->pi_waiters);
+	}
+	spin_unlock_irqrestore(&pendowner->pi_lock, flags);
+
+	wake_up_process(pendowner);
+}
+
+/*
+ * Remove a waiter from a lock
+ *
+ * Must be called with lock->wait_lock held
+ */
+static void remove_waiter(struct rt_mutex *lock,
+			  struct rt_mutex_waiter *waiter  __IP_DECL__)
+{
+	int first = (waiter == rt_mutex_top_waiter(lock));
+	int boost = 0;
+	task_t *owner = rt_mutex_owner(lock);
+	unsigned long flags;
+
+	spin_lock_irqsave(&current->pi_lock, flags);
+	plist_del(&waiter->list_entry, &lock->wait_list);
+	waiter->task = NULL;
+	current->pi_blocked_on = NULL;
+	spin_unlock_irqrestore(&current->pi_lock, flags);
+
+	if (first && owner != current) {
+
+		spin_lock_irqsave(&owner->pi_lock, flags);
+
+		plist_del(&waiter->pi_list_entry, &owner->pi_waiters);
+
+		if (rt_mutex_has_waiters(lock)) {
+			struct rt_mutex_waiter *next;
+
+			next = rt_mutex_top_waiter(lock);
+			plist_add(&next->pi_list_entry, &owner->pi_waiters);
+		}
+		__rt_mutex_adjust_prio(owner);
+
+		if (owner->pi_blocked_on) {
+			boost = 1;
+			get_task_struct(owner);
+		}
+		spin_unlock_irqrestore(&owner->pi_lock, flags);
+	}
+
+	WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
+
+	if (!boost)
+		return;
+
+	spin_unlock(&lock->wait_lock);
+
+	rt_mutex_adjust_prio_chain(owner, 0, lock, NULL __IP__);
+
+	spin_lock(&lock->wait_lock);
+}
+
+/*
+ * Slow path lock function:
+ */
+static int __sched
+rt_mutex_slowlock(struct rt_mutex *lock, int state,
+		  struct hrtimer_sleeper *timeout,
+		  int detect_deadlock __IP_DECL__)
+{
+	struct rt_mutex_waiter waiter;
+	int ret = 0;
+
+	debug_rt_mutex_init_waiter(&waiter);
+	waiter.task = NULL;
+
+	spin_lock(&lock->wait_lock);
+
+	/* Try to acquire the lock again: */
+	if (try_to_take_rt_mutex(lock __IP__)) {
+		spin_unlock(&lock->wait_lock);
+		return 0;
+	}
+
+	set_current_state(state);
+
+	/* Setup the timer, when timeout != NULL */
+	if (unlikely(timeout))
+		hrtimer_start(&timeout->timer, timeout->timer.expires,
+			      HRTIMER_ABS);
+
+	for (;;) {
+		/* Try to acquire the lock: */
+		if (try_to_take_rt_mutex(lock __IP__))
+			break;
+
+		/*
+		 * TASK_INTERRUPTIBLE checks for signals and
+		 * timeout. Ignored otherwise.
+		 */
+		if (unlikely(state == TASK_INTERRUPTIBLE)) {
+			/* Signal pending? */
+			if (signal_pending(current))
+				ret = -EINTR;
+			if (timeout && !timeout->task)
+				ret = -ETIMEDOUT;
+			if (ret)
+				break;
+		}
+
+		/*
+		 * waiter.task is NULL the first time we come here and
+		 * when we have been woken up by the previous owner
+		 * but the lock got stolen by a higher prio task.
+		 */
+		if (!waiter.task) {
+			ret = task_blocks_on_rt_mutex(lock, &waiter,
+						      detect_deadlock __IP__);
+			/*
+			 * If we got woken up by the owner then start loop
+			 * all over without going into schedule to try
+			 * to get the lock now:
+			 */
+			if (unlikely(!waiter.task))
+				continue;
+
+			if (unlikely(ret))
+				break;
+		}
+		spin_unlock(&lock->wait_lock);
+
+		debug_rt_mutex_print_deadlock(&waiter);
+
+		schedule();
+
+		spin_lock(&lock->wait_lock);
+		set_current_state(state);
+	}
+
+	set_current_state(TASK_RUNNING);
+
+	if (unlikely(waiter.task))
+		remove_waiter(lock, &waiter __IP__);
+
+	/*
+	 * try_to_take_rt_mutex() sets the waiter bit
+	 * unconditionally. We might have to fix that up.
+	 */
+	fixup_rt_mutex_waiters(lock);
+
+	spin_unlock(&lock->wait_lock);
+
+	/* Remove pending timer: */
+	if (unlikely(timeout))
+		hrtimer_cancel(&timeout->timer);
+
+	/*
+	 * Readjust priority, when we did not get the lock. We might
+	 * have been the pending owner and boosted. Since we did not
+	 * take the lock, the PI boost has to go.
+	 */
+	if (unlikely(ret))
+		rt_mutex_adjust_prio(current);
+
+	debug_rt_mutex_free_waiter(&waiter);
+
+	return ret;
+}
+
+/*
+ * Slow path try-lock function:
+ */
+static inline int
+rt_mutex_slowtrylock(struct rt_mutex *lock __IP_DECL__)
+{
+	int ret = 0;
+
+	spin_lock(&lock->wait_lock);
+
+	if (likely(rt_mutex_owner(lock) != current)) {
+
+		ret = try_to_take_rt_mutex(lock __IP__);
+		/*
+		 * try_to_take_rt_mutex() sets the lock waiters
+		 * bit unconditionally. Clean this up.
+		 */
+		fixup_rt_mutex_waiters(lock);
+	}
+
+	spin_unlock(&lock->wait_lock);
+
+	return ret;
+}
+
+/*
+ * Slow path to release a rt-mutex:
+ */
+static void __sched
+rt_mutex_slowunlock(struct rt_mutex *lock)
+{
+	spin_lock(&lock->wait_lock);
+
+	debug_rt_mutex_unlock(lock);
+
+	rt_mutex_deadlock_account_unlock(current);
+
+	if (!rt_mutex_has_waiters(lock)) {
+		lock->owner = NULL;
+		spin_unlock(&lock->wait_lock);
+		return;
+	}
+
+	wakeup_next_waiter(lock);
+
+	spin_unlock(&lock->wait_lock);
+
+	/* Undo pi boosting if necessary: */
+	rt_mutex_adjust_prio(current);
+}
+
+/*
+ * debug aware fast / slowpath lock,trylock,unlock
+ *
+ * The atomic acquire/release ops are compiled away, when either the
+ * architecture does not support cmpxchg or when debugging is enabled.
+ */
+static inline int
+rt_mutex_fastlock(struct rt_mutex *lock, int state,
+		  int detect_deadlock,
+		  int (*slowfn)(struct rt_mutex *lock, int state,
+				struct hrtimer_sleeper *timeout,
+				int detect_deadlock __IP_DECL__))
+{
+	if (!detect_deadlock && likely(rt_mutex_cmpxchg(lock, NULL, current))) {
+		rt_mutex_deadlock_account_lock(lock, current);
+		return 0;
+	} else
+		return slowfn(lock, state, NULL, detect_deadlock __RET_IP__);
+}
+
+static inline int
+rt_mutex_timed_fastlock(struct rt_mutex *lock, int state,
+			struct hrtimer_sleeper *timeout, int detect_deadlock,
+			int (*slowfn)(struct rt_mutex *lock, int state,
+				      struct hrtimer_sleeper *timeout,
+				      int detect_deadlock __IP_DECL__))
+{
+	if (!detect_deadlock && likely(rt_mutex_cmpxchg(lock, NULL, current))) {
+		rt_mutex_deadlock_account_lock(lock, current);
+		return 0;
+	} else
+		return slowfn(lock, state, timeout, detect_deadlock __RET_IP__);
+}
+
+static inline int
+rt_mutex_fasttrylock(struct rt_mutex *lock,
+		     int (*slowfn)(struct rt_mutex *lock __IP_DECL__))
+{
+	if (likely(rt_mutex_cmpxchg(lock, NULL, current))) {
+		rt_mutex_deadlock_account_lock(lock, current);
+		return 1;
+	}
+	return slowfn(lock __RET_IP__);
+}
+
+static inline void
+rt_mutex_fastunlock(struct rt_mutex *lock,
+		    void (*slowfn)(struct rt_mutex *lock))
+{
+	if (likely(rt_mutex_cmpxchg(lock, current, NULL)))
+		rt_mutex_deadlock_account_unlock(current);
+	else
+		slowfn(lock);
+}
+
+/**
+ * rt_mutex_lock - lock a rt_mutex
+ *
+ * @lock: the rt_mutex to be locked
+ */
+void __sched rt_mutex_lock(struct rt_mutex *lock)
+{
+	might_sleep();
+
+	rt_mutex_fastlock(lock, TASK_UNINTERRUPTIBLE, 0, rt_mutex_slowlock);
+}
+EXPORT_SYMBOL_GPL(rt_mutex_lock);
+
+/**
+ * rt_mutex_lock_interruptible - lock a rt_mutex interruptible
+ *
+ * @lock: 		the rt_mutex to be locked
+ * @detect_deadlock:	deadlock detection on/off
+ *
+ * Returns:
+ *  0 		on success
+ * -EINTR 	when interrupted by a signal
+ * -EDEADLK	when the lock would deadlock (when deadlock detection is on)
+ */
+int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock,
+						 int detect_deadlock)
+{
+	might_sleep();
+
+	return rt_mutex_fastlock(lock, TASK_INTERRUPTIBLE,
+				 detect_deadlock, rt_mutex_slowlock);
+}
+EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible);
+
+/**
+ * rt_mutex_lock_interruptible_ktime - lock a rt_mutex interruptible
+ *				       the timeout structure is provided
+ *				       by the caller
+ *
+ * @lock: 		the rt_mutex to be locked
+ * @timeout:		timeout structure or NULL (no timeout)
+ * @detect_deadlock:	deadlock detection on/off
+ *
+ * Returns:
+ *  0 		on success
+ * -EINTR 	when interrupted by a signal
+ * -ETIMEOUT	when the timeout expired
+ * -EDEADLK	when the lock would deadlock (when deadlock detection is on)
+ */
+int
+rt_mutex_timed_lock(struct rt_mutex *lock, struct hrtimer_sleeper *timeout,
+		    int detect_deadlock)
+{
+	might_sleep();
+
+	return rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timeout,
+				       detect_deadlock, rt_mutex_slowlock);
+}
+EXPORT_SYMBOL_GPL(rt_mutex_timed_lock);
+
+/**
+ * rt_mutex_trylock - try to lock a rt_mutex
+ *
+ * @lock:	the rt_mutex to be locked
+ *
+ * Returns 1 on success and 0 on contention
+ */
+int __sched rt_mutex_trylock(struct rt_mutex *lock)
+{
+	return rt_mutex_fasttrylock(lock, rt_mutex_slowtrylock);
+}
+EXPORT_SYMBOL_GPL(rt_mutex_trylock);
+
+/**
+ * rt_mutex_unlock - unlock a rt_mutex
+ *
+ * @lock: the rt_mutex to be unlocked
+ */
+void __sched rt_mutex_unlock(struct rt_mutex *lock)
+{
+	rt_mutex_fastunlock(lock, rt_mutex_slowunlock);
+}
+EXPORT_SYMBOL_GPL(rt_mutex_unlock);
+
+/***
+ * rt_mutex_destroy - mark a mutex unusable
+ * @lock: the mutex to be destroyed
+ *
+ * This function marks the mutex uninitialized, and any subsequent
+ * use of the mutex is forbidden. The mutex must not be locked when
+ * this function is called.
+ */
+void rt_mutex_destroy(struct rt_mutex *lock)
+{
+	WARN_ON(rt_mutex_is_locked(lock));
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+	lock->magic = NULL;
+#endif
+}
+
+EXPORT_SYMBOL_GPL(rt_mutex_destroy);
+
+/**
+ * __rt_mutex_init - initialize the rt lock
+ *
+ * @lock: the rt lock to be initialized
+ *
+ * Initialize the rt lock to unlocked state.
+ *
+ * Initializing of a locked rt lock is not allowed
+ */
+void __rt_mutex_init(struct rt_mutex *lock, const char *name)
+{
+	lock->owner = NULL;
+	spin_lock_init(&lock->wait_lock);
+	plist_head_init(&lock->wait_list, &lock->wait_lock);
+
+	debug_rt_mutex_init(lock, name);
+}
+EXPORT_SYMBOL_GPL(__rt_mutex_init);
+/*
+ * RT-Mutexes: blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner:
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *
+ * This file contains macros used solely by rtmutex.c.
+ * Non-debug version.
+ */
+
+#define __IP_DECL__
+#define __IP__
+#define __RET_IP__
+#define rt_mutex_deadlock_check(l)			(0)
+#define rt_mutex_deadlock_account_lock(m, t)		do { } while (0)
+#define rt_mutex_deadlock_account_unlock(l)		do { } while (0)
+#define debug_rt_mutex_init_waiter(w)			do { } while (0)
+#define debug_rt_mutex_free_waiter(w)			do { } while (0)
+#define debug_rt_mutex_lock(l)				do { } while (0)
+#define debug_rt_mutex_proxy_lock(l,p)			do { } while (0)
+#define debug_rt_mutex_proxy_unlock(l)			do { } while (0)
+#define debug_rt_mutex_unlock(l)			do { } while (0)
+#define debug_rt_mutex_init(m, n)			do { } while (0)
+#define debug_rt_mutex_deadlock(d, a ,l)		do { } while (0)
+#define debug_rt_mutex_print_deadlock(w)		do { } while (0)
+#define debug_rt_mutex_detect_deadlock(w,d)		(d)
+#define debug_rt_mutex_reset_waiter(w)			do { } while (0)
+/*
+ * RT Mutexes: blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner:
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *
+ * This file contains the private data structure and API definitions.
+ */
+
+#ifndef __KERNEL_RTMUTEX_COMMON_H
+#define __KERNEL_RTMUTEX_COMMON_H
+
+#include <linux/rtmutex.h>
+
+/*
+ * This is the control structure for tasks blocked on a rt_mutex,
+ * which is allocated on the kernel stack on of the blocked task.
+ *
+ * @list_entry:		pi node to enqueue into the mutex waiters list
+ * @pi_list_entry:	pi node to enqueue into the mutex owner waiters list
+ * @task:		task reference to the blocked task
+ */
+struct rt_mutex_waiter {
+	struct plist_node	list_entry;
+	struct plist_node	pi_list_entry;
+	struct task_struct	*task;
+	struct rt_mutex		*lock;
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+	unsigned long		ip;
+	pid_t			deadlock_task_pid;
+	struct rt_mutex		*deadlock_lock;
+#endif
+};
+
+/*
+ * Various helpers to access the waiters-plist:
+ */
+static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
+{
+	return !plist_head_empty(&lock->wait_list);
+}
+
+static inline struct rt_mutex_waiter *
+rt_mutex_top_waiter(struct rt_mutex *lock)
+{
+	struct rt_mutex_waiter *w;
+
+	w = plist_first_entry(&lock->wait_list, struct rt_mutex_waiter,
+			       list_entry);
+	BUG_ON(w->lock != lock);
+
+	return w;
+}
+
+static inline int task_has_pi_waiters(struct task_struct *p)
+{
+	return !plist_head_empty(&p->pi_waiters);
+}
+
+static inline struct rt_mutex_waiter *
+task_top_pi_waiter(struct task_struct *p)
+{
+	return plist_first_entry(&p->pi_waiters, struct rt_mutex_waiter,
+				  pi_list_entry);
+}
+
+/*
+ * lock->owner state tracking:
+ */
+#define RT_MUTEX_OWNER_PENDING	1UL
+#define RT_MUTEX_HAS_WAITERS	2UL
+#define RT_MUTEX_OWNER_MASKALL	3UL
+
+static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
+{
+	return (struct task_struct *)
+		((unsigned long)lock->owner & ~RT_MUTEX_OWNER_MASKALL);
+}
+
+static inline struct task_struct *rt_mutex_real_owner(struct rt_mutex *lock)
+{
+ 	return (struct task_struct *)
+		((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS);
+}
+
+static inline unsigned long rt_mutex_owner_pending(struct rt_mutex *lock)
+{
+	return (unsigned long)lock->owner & RT_MUTEX_OWNER_PENDING;
+}
+
+#endif
@@ -133,6 +133,10 @@
 extern int no_unaligned_warning;
 #endif
  
+#ifdef CONFIG_RT_MUTEXES
+extern int max_lock_depth;
+#endif
+
 static int parse_table(int __user *, int, void __user *, size_t __user *, void __user *, size_t,
 		       ctl_table *, void **);
 static int proc_doutsstring(ctl_table *table, int write, struct file *filp,
@@ -688,6 +692,17 @@
 		.proc_handler	= &proc_dointvec,
 	},
 #endif
+#ifdef CONFIG_RT_MUTEXES
+	{
+		.ctl_name	= KERN_MAX_LOCK_DEPTH,
+		.procname	= "max_lock_depth",
+		.data		= &max_lock_depth,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
+#endif
+
 	{ .ctl_name = 0 }
 };
...	...	@@ -124,6 +124,7 @@
124	124	.cpu_timers = INIT_CPU_TIMERS(tsk.cpu_timers), \
125	125	.fs_excl = ATOMIC_INIT(0), \
126	126	.pi_lock = SPIN_LOCK_UNLOCKED, \
	127	+ INIT_RT_MUTEXES(tsk) \
127	128	}
128	129
129	130
	1	+/*
	2	+ * RT Mutexes: blocking mutual exclusion locks with PI support
	3	+ *
	4	+ * started by Ingo Molnar and Thomas Gleixner:
	5	+ *
	6	+ * Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
	7	+ * Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
	8	+ *
	9	+ * This file contains the public data structure and API definitions.
	10	+ */
	11	+
	12	+#ifndef __LINUX_RT_MUTEX_H
	13	+#define __LINUX_RT_MUTEX_H
	14	+
	15	+#include <linux/linkage.h>
	16	+#include <linux/plist.h>
	17	+#include <linux/spinlock_types.h>
	18	+
	19	+/*
	20	+ * The rt_mutex structure
	21	+ *
	22	+ * @wait_lock: spinlock to protect the structure
	23	+ * @wait_list: pilist head to enqueue waiters in priority order
	24	+ * @owner: the mutex owner
	25	+ */
	26	+struct rt_mutex {
	27	+ spinlock_t wait_lock;
	28	+ struct plist_head wait_list;
	29	+ struct task_struct *owner;
	30	+#ifdef CONFIG_DEBUG_RT_MUTEXES
	31	+ int save_state;
	32	+ struct list_head held_list_entry;
	33	+ unsigned long acquire_ip;
	34	+ const char name, file;
	35	+ int line;
	36	+ void *magic;
	37	+#endif
	38	+};
	39	+
	40	+struct rt_mutex_waiter;
	41	+struct hrtimer_sleeper;
	42	+
	43	+#ifdef CONFIG_DEBUG_RT_MUTEXES
	44	+# define __DEBUG_RT_MUTEX_INITIALIZER(mutexname) \
	45	+ , .name = #mutexname, .file = __FILE__, .line = __LINE__
	46	+# define rt_mutex_init(mutex) __rt_mutex_init(mutex, __FUNCTION__)
	47	+ extern void rt_mutex_debug_task_free(struct task_struct *tsk);
	48	+#else
	49	+# define __DEBUG_RT_MUTEX_INITIALIZER(mutexname)
	50	+# define rt_mutex_init(mutex) __rt_mutex_init(mutex, NULL)
	51	+# define rt_mutex_debug_task_free(t) do { } while (0)
	52	+#endif
	53	+
	54	+#define __RT_MUTEX_INITIALIZER(mutexname) \
	55	+ { .wait_lock = SPIN_LOCK_UNLOCKED \
	56	+ , .wait_list = PLIST_HEAD_INIT(mutexname.wait_list, mutexname.wait_lock) \
	57	+ , .owner = NULL \
	58	+ __DEBUG_RT_MUTEX_INITIALIZER(mutexname)}
	59	+
	60	+#define DEFINE_RT_MUTEX(mutexname) \
	61	+ struct rt_mutex mutexname = __RT_MUTEX_INITIALIZER(mutexname)
	62	+
	63	+/***
	64	+ * rt_mutex_is_locked - is the mutex locked
	65	+ * @lock: the mutex to be queried
	66	+ *
	67	+ * Returns 1 if the mutex is locked, 0 if unlocked.
	68	+ */
	69	+static inline int rt_mutex_is_locked(struct rt_mutex *lock)
	70	+{
	71	+ return lock->owner != NULL;
	72	+}
	73	+
	74	+extern void __rt_mutex_init(struct rt_mutex lock, const char name);
	75	+extern void rt_mutex_destroy(struct rt_mutex *lock);
	76	+
	77	+extern void rt_mutex_lock(struct rt_mutex *lock);
	78	+extern int rt_mutex_lock_interruptible(struct rt_mutex *lock,
	79	+ int detect_deadlock);
	80	+extern int rt_mutex_timed_lock(struct rt_mutex *lock,
	81	+ struct hrtimer_sleeper *timeout,
	82	+ int detect_deadlock);
	83	+
	84	+extern int rt_mutex_trylock(struct rt_mutex *lock);
	85	+
	86	+extern void rt_mutex_unlock(struct rt_mutex *lock);
	87	+
	88	+#ifdef CONFIG_DEBUG_RT_MUTEXES
	89	+# define INIT_RT_MUTEX_DEBUG(tsk) \
	90	+ .held_list_head = LIST_HEAD_INIT(tsk.held_list_head), \
	91	+ .held_list_lock = SPIN_LOCK_UNLOCKED
	92	+#else
	93	+# define INIT_RT_MUTEX_DEBUG(tsk)
	94	+#endif
	95	+
	96	+#ifdef CONFIG_RT_MUTEXES
	97	+# define INIT_RT_MUTEXES(tsk) \
	98	+ .pi_waiters = PLIST_HEAD_INIT(tsk.pi_waiters, tsk.pi_lock), \
	99	+ INIT_RT_MUTEX_DEBUG(tsk)
	100	+#else
	101	+# define INIT_RT_MUTEXES(tsk)
	102	+#endif
	103	+
	104	+#endif
...	...	@@ -73,6 +73,7 @@
73	73	#include <linux/seccomp.h>
74	74	#include <linux/rcupdate.h>
75	75	#include <linux/futex.h>
	76	+#include <linux/rtmutex.h>
76	77
77	78	#include <linux/time.h>
78	79	#include <linux/param.h>
...	...	@@ -857,6 +858,17 @@
857	858
858	859	/* Protection of the PI data structures: */
859	860	spinlock_t pi_lock;
	861	+
	862	+#ifdef CONFIG_RT_MUTEXES
	863	+ /* PI waiters blocked on a rt_mutex held by this task */
	864	+ struct plist_head pi_waiters;
	865	+ /* Deadlock detection and priority inheritance handling */
	866	+ struct rt_mutex_waiter *pi_blocked_on;
	867	+# ifdef CONFIG_DEBUG_RT_MUTEXES
	868	+ spinlock_t held_list_lock;
	869	+ struct list_head held_list_head;
	870	+# endif
	871	+#endif
860	872
861	873	#ifdef CONFIG_DEBUG_MUTEXES
862	874	/* mutex deadlock detection */
...	...	@@ -149,6 +149,7 @@
149	149	KERN_ACPI_VIDEO_FLAGS=71, /* int: flags for setting up video after ACPI sleep */
150	150	KERN_IA64_UNALIGNED=72, /* int: ia64 unaligned userland trap enable */
151	151	KERN_COMPAT_LOG=73, /* int: print compat layer messages */
	152	+ KERN_MAX_LOCK_DEPTH=74,
152	153	};
153	154
154	155
...	...	@@ -339,9 +339,14 @@
339	339	kernel data structures. This saves memory on small machines,
340	340	but may reduce performance.
341	341
	342	+config RT_MUTEXES
	343	+ boolean
	344	+ select PLIST
	345	+
342	346	config FUTEX
343	347	bool "Enable futex support" if EMBEDDED
344	348	default y
	349	+ select RT_MUTEXES
345	350	help
346	351	Disabling this option will cause the kernel to be built without
347	352	support for "fast userspace mutexes". The resulting kernel may not
...	...	@@ -16,6 +16,7 @@
16	16	ifeq ($(CONFIG_COMPAT),y)
17	17	obj-$(CONFIG_FUTEX) += futex_compat.o
18	18	endif
	19	+obj-$(CONFIG_RT_MUTEXES) += rtmutex.o
19	20	obj-$(CONFIG_GENERIC_ISA_DMA) += dma.o
20	21	obj-$(CONFIG_SMP) += cpu.o spinlock.o
21	22	obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o
...	...	@@ -104,6 +104,7 @@
104	104	void free_task(struct task_struct *tsk)
105	105	{
106	106	free_thread_info(tsk->thread_info);
	107	+ rt_mutex_debug_task_free(tsk);
107	108	free_task_struct(tsk);
108	109	}
109	110	EXPORT_SYMBOL(free_task);
...	...	@@ -913,6 +914,19 @@
913	914	return current->pid;
914	915	}
915	916
	917	+static inline void rt_mutex_init_task(struct task_struct *p)
	918	+{
	919	+#ifdef CONFIG_RT_MUTEXES
	920	+ spin_lock_init(&p->pi_lock);
	921	+ plist_head_init(&p->pi_waiters, &p->pi_lock);
	922	+ p->pi_blocked_on = NULL;
	923	+# ifdef CONFIG_DEBUG_RT_MUTEXES
	924	+ spin_lock_init(&p->held_list_lock);
	925	+ INIT_LIST_HEAD(&p->held_list_head);
	926	+# endif
	927	+#endif
	928	+}
	929	+
916	930	/*
917	931	* This creates a new process as a copy of the old one,
918	932	* but does not actually start it yet.
...	...	@@ -1033,6 +1047,8 @@
1033	1047	}
1034	1048	mpol_fix_fork_child_flag(p);
1035	1049	#endif
	1050	+
	1051	+ rt_mutex_init_task(p);
1036	1052
1037	1053	#ifdef CONFIG_DEBUG_MUTEXES
1038	1054	p->blocked_on = NULL; /* not blocked yet */
	1	+/*
	2	+ * RT-Mutexes: blocking mutual exclusion locks with PI support
	3	+ *
	4	+ * started by Ingo Molnar and Thomas Gleixner:
	5	+ *
	6	+ * Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
	7	+ * Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
	8	+ *
	9	+ * This file contains macros used solely by rtmutex.c.
	10	+ * Non-debug version.
	11	+ */
	12	+
	13	+#define __IP_DECL__
	14	+#define __IP__
	15	+#define __RET_IP__
	16	+#define rt_mutex_deadlock_check(l) (0)
	17	+#define rt_mutex_deadlock_account_lock(m, t) do { } while (0)
	18	+#define rt_mutex_deadlock_account_unlock(l) do { } while (0)
	19	+#define debug_rt_mutex_init_waiter(w) do { } while (0)
	20	+#define debug_rt_mutex_free_waiter(w) do { } while (0)
	21	+#define debug_rt_mutex_lock(l) do { } while (0)
	22	+#define debug_rt_mutex_proxy_lock(l,p) do { } while (0)
	23	+#define debug_rt_mutex_proxy_unlock(l) do { } while (0)
	24	+#define debug_rt_mutex_unlock(l) do { } while (0)
	25	+#define debug_rt_mutex_init(m, n) do { } while (0)
	26	+#define debug_rt_mutex_deadlock(d, a ,l) do { } while (0)
	27	+#define debug_rt_mutex_print_deadlock(w) do { } while (0)
	28	+#define debug_rt_mutex_detect_deadlock(w,d) (d)
	29	+#define debug_rt_mutex_reset_waiter(w) do { } while (0)
...	...	@@ -133,6 +133,10 @@
133	133	extern int no_unaligned_warning;
134	134	#endif
135	135
	136	+#ifdef CONFIG_RT_MUTEXES
	137	+extern int max_lock_depth;
	138	+#endif
	139	+
136	140	static int parse_table(int __user , int, void __user , size_t __user , void __user , size_t,
137	141	ctl_table , void *);
138	142	static int proc_doutsstring(ctl_table table, int write, struct file filp,
...	...	@@ -688,6 +692,17 @@
688	692	.proc_handler = &proc_dointvec,
689	693	},
690	694	#endif
	695	+#ifdef CONFIG_RT_MUTEXES
	696	+ {
	697	+ .ctl_name = KERN_MAX_LOCK_DEPTH,
	698	+ .procname = "max_lock_depth",
	699	+ .data = &max_lock_depth,
	700	+ .maxlen = sizeof(int),
	701	+ .mode = 0644,
	702	+ .proc_handler = &proc_dointvec,
	703	+ },
	704	+#endif
	705	+
691	706	{ .ctl_name = 0 }
692	707	};
693	708