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

* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  rtmutex: tester: Remove the remaining BKL leftovers
  lockdep/timers: Explain in detail the locking problems del_timer_sync() may cause
  rtmutex: Simplify PI algorithm and make highest prio task get lock
  rwsem: Remove redundant asmregparm annotation
  rwsem: Move duplicate function prototypes to linux/rwsem.h
  rwsem: Unify the duplicate rwsem_is_locked() inlines
  rwsem: Move duplicate init macros and functions to linux/rwsem.h
  rwsem: Move duplicate struct rwsem declaration to linux/rwsem.h
  x86: Cleanup rwsem_count_t typedef
  rwsem: Cleanup includes
  locking: Remove deprecated lock initializers
  cred: Replace deprecated spinlock initialization
  kthread: Replace deprecated spinlock initialization
  xtensa: Replace deprecated spinlock initialization
  um: Replace deprecated spinlock initialization
  sparc: Replace deprecated spinlock initialization
  mips: Replace deprecated spinlock initialization
  cris: Replace deprecated spinlock initialization
  alpha: Replace deprecated spinlock initialization
  rtmutex-tester: Remove BKL tests

7 files changed, 155 insertions, 267 deletions

diff --git a/kernel/cred.c b/kernel/cred.c
index 3a9d6dd53a6c..2343c132c5a7 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -35,7 +35,7 @@ static struct kmem_cache *cred_jar;
 static struct thread_group_cred init_tgcred = {
         .usage  = ATOMIC_INIT(2),
         .tgid   = 0,
-        .lock   = SPIN_LOCK_UNLOCKED,
+        .lock   = __SPIN_LOCK_UNLOCKED(init_cred.tgcred.lock),
 };
 #endif
 
diff --git a/kernel/futex.c b/kernel/futex.c
index e9251d934f7d..bda415715382 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1555,10 +1555,10 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
 
         /*
          * We are here either because we stole the rtmutex from the
-         * pending owner or we are the pending owner which failed to
-         * get the rtmutex. We have to replace the pending owner TID
-         * in the user space variable. This must be atomic as we have
-         * to preserve the owner died bit here.
+         * previous highest priority waiter or we are the highest priority
+         * waiter but failed to get the rtmutex the first time.
+         * We have to replace the newowner TID in the user space variable.
+         * This must be atomic as we have to preserve the owner died bit here.
          *
          * Note: We write the user space value _before_ changing the pi_state
          * because we can fault here. Imagine swapped out pages or a fork
@@ -1605,8 +1605,8 @@ retry:
 
         /*
          * To handle the page fault we need to drop the hash bucket
-         * lock here. That gives the other task (either the pending
-         * owner itself or the task which stole the rtmutex) the
+         * lock here. That gives the other task (either the highest priority
+         * waiter itself or the task which stole the rtmutex) the
          * chance to try the fixup of the pi_state. So once we are
          * back from handling the fault we need to check the pi_state
          * after reacquiring the hash bucket lock and before trying to
@@ -1682,18 +1682,20 @@ static int fixup_owner(u32 __user *uaddr, struct futex_q *q, int locked)
                 /*
                  * pi_state is incorrect, some other task did a lock steal and
                  * we returned due to timeout or signal without taking the
-                 * rt_mutex. Too late. We can access the rt_mutex_owner without
-                 * locking, as the other task is now blocked on the hash bucket
-                 * lock. Fix the state up.
+                 * rt_mutex. Too late.
                  */
+                raw_spin_lock(&q->pi_state->pi_mutex.wait_lock);
                 owner = rt_mutex_owner(&q->pi_state->pi_mutex);
+                if (!owner)
+                        owner = rt_mutex_next_owner(&q->pi_state->pi_mutex);
+                raw_spin_unlock(&q->pi_state->pi_mutex.wait_lock);
                 ret = fixup_pi_state_owner(uaddr, q, owner);
                 goto out;
         }
 
         /*
          * Paranoia check. If we did not take the lock, then we should not be
-         * the owner, nor the pending owner, of the rt_mutex.
+         * the owner of the rt_mutex.
          */
         if (rt_mutex_owner(&q->pi_state->pi_mutex) == current)
                 printk(KERN_ERR "fixup_owner: ret = %d pi-mutex: %p "
diff --git a/kernel/rtmutex-debug.c b/kernel/rtmutex-debug.c
index ddabb54bb5c8..3c7cbc2c33be 100644
--- a/kernel/rtmutex-debug.c
+++ b/kernel/rtmutex-debug.c
@@ -215,7 +215,6 @@ void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
         put_pid(waiter->deadlock_task_pid);
         TRACE_WARN_ON(!plist_node_empty(&waiter->list_entry));
         TRACE_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
-        TRACE_WARN_ON(waiter->task);
         memset(waiter, 0x22, sizeof(*waiter));
 }
 
diff --git a/kernel/rtmutex-tester.c b/kernel/rtmutex-tester.c
index 66cb89bc5ef1..5c9ccd380966 100644
--- a/kernel/rtmutex-tester.c
+++ b/kernel/rtmutex-tester.c
@@ -9,7 +9,6 @@
 #include <linux/kthread.h>
 #include <linux/module.h>
 #include <linux/sched.h>
-#include <linux/smp_lock.h>
 #include <linux/spinlock.h>
 #include <linux/sysdev.h>
 #include <linux/timer.h>
@@ -27,7 +26,6 @@ struct test_thread_data {
         int                     opcode;
         int                     opdata;
         int                     mutexes[MAX_RT_TEST_MUTEXES];
-        int                     bkl;
         int                     event;
         struct sys_device       sysdev;
 };
@@ -46,9 +44,8 @@ enum test_opcodes {
         RTTEST_LOCKINTNOWAIT,   /* 6 Lock interruptible no wait in wakeup, data = lockindex */
         RTTEST_LOCKCONT,        /* 7 Continue locking after the wakeup delay */
         RTTEST_UNLOCK,          /* 8 Unlock, data = lockindex */
-        RTTEST_LOCKBKL,         /* 9 Lock BKL */
-        RTTEST_UNLOCKBKL,       /* 10 Unlock BKL */
-        RTTEST_SIGNAL,          /* 11 Signal other test thread, data = thread id */
+        /* 9, 10 - reserved for BKL commemoration */
+        RTTEST_SIGNAL = 11,     /* 11 Signal other test thread, data = thread id */
         RTTEST_RESETEVENT = 98, /* 98 Reset event counter */
         RTTEST_RESET = 99,      /* 99 Reset all pending operations */
 };
@@ -74,13 +71,6 @@ static int handle_op(struct test_thread_data *td, int lockwakeup)
                                 td->mutexes[i] = 0;
                         }
                 }
-
-                if (!lockwakeup && td->bkl == 4) {
-#ifdef CONFIG_LOCK_KERNEL
-                        unlock_kernel();
-#endif
-                        td->bkl = 0;
-                }
                 return 0;
 
         case RTTEST_RESETEVENT:
@@ -131,25 +121,6 @@ static int handle_op(struct test_thread_data *td, int lockwakeup)
                 td->mutexes[id] = 0;
                 return 0;
 
-        case RTTEST_LOCKBKL:
-                if (td->bkl)
-                        return 0;
-                td->bkl = 1;
-#ifdef CONFIG_LOCK_KERNEL
-                lock_kernel();
-#endif
-                td->bkl = 4;
-                return 0;
-
-        case RTTEST_UNLOCKBKL:
-                if (td->bkl != 4)
-                        break;
-#ifdef CONFIG_LOCK_KERNEL
-                unlock_kernel();
-#endif
-                td->bkl = 0;
-                return 0;
-
         default:
                 break;
         }
@@ -196,7 +167,6 @@ void schedule_rt_mutex_test(struct rt_mutex *mutex)
                 td->event = atomic_add_return(1, &rttest_event);
                 break;
 
-        case RTTEST_LOCKBKL:
         default:
                 break;
         }
@@ -229,8 +199,6 @@ void schedule_rt_mutex_test(struct rt_mutex *mutex)
                 td->event = atomic_add_return(1, &rttest_event);
                 return;
 
-        case RTTEST_LOCKBKL:
-                return;
         default:
                 return;
         }
@@ -380,11 +348,11 @@ static ssize_t sysfs_test_status(struct sys_device *dev, struct sysdev_attribute
         spin_lock(&rttest_lock);
 
         curr += sprintf(curr,
-                "O: %4d, E:%8d, S: 0x%08lx, P: %4d, N: %4d, B: %p, K: %d, M:",
+                "O: %4d, E:%8d, S: 0x%08lx, P: %4d, N: %4d, B: %p, M:",
                 td->opcode, td->event, tsk->state,
                         (MAX_RT_PRIO - 1) - tsk->prio,
                         (MAX_RT_PRIO - 1) - tsk->normal_prio,
-                tsk->pi_blocked_on, td->bkl);
+                tsk->pi_blocked_on);
 
         for (i = MAX_RT_TEST_MUTEXES - 1; i >=0 ; i--)
                 curr += sprintf(curr, "%d", td->mutexes[i]);
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c
index a9604815786a..ab449117aaf2 100644
--- a/kernel/rtmutex.c
+++ b/kernel/rtmutex.c
@@ -20,41 +20,34 @@
 /*
  * 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.
+ * lock->owner holds the task_struct pointer of the owner. Bit 0
+ * is used to keep track of the "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.
+ * owner        bit0
+ * NULL         0       lock is free (fast acquire possible)
+ * NULL         1       lock is free and has waiters and the top waiter
+ *                              is going to take the lock*
+ * taskpointer  0       lock is held (fast release possible)
+ * taskpointer  1       lock is held and has waiters**
  *
  * The fast atomic compare exchange based acquire and release is only
- * possible when bit 0 and 1 of lock->owner are 0.
+ * possible when bit 0 of lock->owner is 0.
+ *
+ * (*) It also can be a transitional state when grabbing the lock
+ * with ->wait_lock is held. To prevent any fast path cmpxchg to the lock,
+ * we need to set the bit0 before looking at the lock, and the owner may be
+ * NULL in this small time, hence this can be a transitional state.
  *
- * (*) 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.
+ * (**) There is a small time when bit 0 is set but there are no
+ * waiters. This can happen when grabbing the lock in the slow path.
+ * To prevent a cmpxchg of the owner releasing the lock, we need to
+ * set this bit before looking at the lock.
  */
 
 static void
-rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner,
-                   unsigned long mask)
+rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner)
 {
-        unsigned long val = (unsigned long)owner | mask;
+        unsigned long val = (unsigned long)owner;
 
         if (rt_mutex_has_waiters(lock))
                 val |= RT_MUTEX_HAS_WAITERS;
@@ -203,15 +196,14 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
          * reached or the state of the chain has changed while we
          * dropped the locks.
          */
-        if (!waiter || !waiter->task)
+        if (!waiter)
                 goto out_unlock_pi;
 
         /*
          * Check the orig_waiter state. After we dropped the locks,
-         * the previous owner of the lock might have released the lock
-         * and made us the pending owner:
+         * the previous owner of the lock might have released the lock.
          */
-        if (orig_waiter && !orig_waiter->task)
+        if (orig_waiter && !rt_mutex_owner(orig_lock))
                 goto out_unlock_pi;
 
         /*
@@ -254,6 +246,17 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
 
         /* Release the task */
         raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+        if (!rt_mutex_owner(lock)) {
+                /*
+                 * If the requeue above changed the top waiter, then we need
+                 * to wake the new top waiter up to try to get the lock.
+                 */
+
+                if (top_waiter != rt_mutex_top_waiter(lock))
+                        wake_up_process(rt_mutex_top_waiter(lock)->task);
+                raw_spin_unlock(&lock->wait_lock);
+                goto out_put_task;
+        }
         put_task_struct(task);
 
         /* Grab the next task */
@@ -296,78 +299,16 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
 }
 
 /*
- * 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 *task)
-{
-        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 == task)
-                return 1;
-
-        raw_spin_lock_irqsave(&pendowner->pi_lock, flags);
-        if (task->prio >= pendowner->prio) {
-                raw_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))) {
-                raw_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);
-        raw_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
-         * task->pi_waiters list. This covers the case,
-         * where task 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 task->normal_prio.
-         *
-         * Note: in the rare case of a SCHED_OTHER task changing
-         * its priority and thus stealing the lock, next->task
-         * might be task:
-         */
-        if (likely(next->task != task)) {
-                raw_spin_lock_irqsave(&task->pi_lock, flags);
-                plist_add(&next->pi_list_entry, &task->pi_waiters);
-                __rt_mutex_adjust_prio(task);
-                raw_spin_unlock_irqrestore(&task->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.
+ *
+ * @lock:   the lock to be acquired.
+ * @task:   the task which wants to acquire the lock
+ * @waiter: the waiter that is queued to the lock's wait list. (could be NULL)
  */
-static int try_to_take_rt_mutex(struct rt_mutex *lock)
+static int try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task,
+                struct rt_mutex_waiter *waiter)
 {
         /*
          * We have to be careful here if the atomic speedups are
@@ -390,15 +331,52 @@ static int try_to_take_rt_mutex(struct rt_mutex *lock)
          */
         mark_rt_mutex_waiters(lock);
 
-        if (rt_mutex_owner(lock) && !try_to_steal_lock(lock, current))
+        if (rt_mutex_owner(lock))
                 return 0;
 
+        /*
+         * It will get the lock because of one of these conditions:
+         * 1) there is no waiter
+         * 2) higher priority than waiters
+         * 3) it is top waiter
+         */
+        if (rt_mutex_has_waiters(lock)) {
+                if (task->prio >= rt_mutex_top_waiter(lock)->list_entry.prio) {
+                        if (!waiter || waiter != rt_mutex_top_waiter(lock))
+                                return 0;
+                }
+        }
+
+        if (waiter || rt_mutex_has_waiters(lock)) {
+                unsigned long flags;
+                struct rt_mutex_waiter *top;
+
+                raw_spin_lock_irqsave(&task->pi_lock, flags);
+
+                /* remove the queued waiter. */
+                if (waiter) {
+                        plist_del(&waiter->list_entry, &lock->wait_list);
+                        task->pi_blocked_on = NULL;
+                }
+
+                /*
+                 * We have to enqueue the top waiter(if it exists) into
+                 * task->pi_waiters list.
+                 */
+                if (rt_mutex_has_waiters(lock)) {
+                        top = rt_mutex_top_waiter(lock);
+                        top->pi_list_entry.prio = top->list_entry.prio;
+                        plist_add(&top->pi_list_entry, &task->pi_waiters);
+                }
+                raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+        }
+
         /* We got the lock. */
         debug_rt_mutex_lock(lock);
 
-        rt_mutex_set_owner(lock, current, 0);
+        rt_mutex_set_owner(lock, task);
 
-        rt_mutex_deadlock_account_lock(lock, current);
+        rt_mutex_deadlock_account_lock(lock, task);
 
         return 1;
 }
@@ -436,6 +414,9 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
 
         raw_spin_unlock_irqrestore(&task->pi_lock, flags);
 
+        if (!owner)
+                return 0;
+
         if (waiter == rt_mutex_top_waiter(lock)) {
                 raw_spin_lock_irqsave(&owner->pi_lock, flags);
                 plist_del(&top_waiter->pi_list_entry, &owner->pi_waiters);
@@ -472,21 +453,18 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
 /*
  * 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.
+ * Remove the top waiter from the current tasks waiter list and 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;
 
         raw_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
@@ -495,43 +473,19 @@ static void wakeup_next_waiter(struct rt_mutex *lock)
          * 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);
+        rt_mutex_set_owner(lock, NULL);
 
         raw_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.
-         */
-        raw_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);
-        }
-        raw_spin_unlock_irqrestore(&pendowner->pi_lock, flags);
-
-        wake_up_process(pendowner);
+        wake_up_process(waiter->task);
 }
 
 /*
- * Remove a waiter from a lock
+ * Remove a waiter from a lock and give up
  *
- * Must be called with lock->wait_lock held
+ * Must be called with lock->wait_lock held and
+ * have just failed to try_to_take_rt_mutex().
  */
 static void remove_waiter(struct rt_mutex *lock,
                           struct rt_mutex_waiter *waiter)
@@ -543,11 +497,13 @@ static void remove_waiter(struct rt_mutex *lock,
 
         raw_spin_lock_irqsave(&current->pi_lock, flags);
         plist_del(&waiter->list_entry, &lock->wait_list);
-        waiter->task = NULL;
         current->pi_blocked_on = NULL;
         raw_spin_unlock_irqrestore(&current->pi_lock, flags);
 
-        if (first && owner != current) {
+        if (!owner)
+                return;
+
+        if (first) {
 
                 raw_spin_lock_irqsave(&owner->pi_lock, flags);
 
@@ -614,21 +570,19 @@ void rt_mutex_adjust_pi(struct task_struct *task)
  *                       or TASK_UNINTERRUPTIBLE)
  * @timeout:             the pre-initialized and started timer, or NULL for none
  * @waiter:              the pre-initialized rt_mutex_waiter
- * @detect_deadlock:     passed to task_blocks_on_rt_mutex
  *
  * lock->wait_lock must be held by the caller.
  */
 static int __sched
 __rt_mutex_slowlock(struct rt_mutex *lock, int state,
                     struct hrtimer_sleeper *timeout,
-                    struct rt_mutex_waiter *waiter,
-                    int detect_deadlock)
+                    struct rt_mutex_waiter *waiter)
 {
         int ret = 0;
 
         for (;;) {
                 /* Try to acquire the lock: */
-                if (try_to_take_rt_mutex(lock))
+                if (try_to_take_rt_mutex(lock, current, waiter))
                         break;
 
                 /*
@@ -645,39 +599,11 @@ __rt_mutex_slowlock(struct rt_mutex *lock, int state,
                                 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, current,
-                                                      detect_deadlock);
-                        /*
-                         * 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)) {
-                                /*
-                                 * Reset the return value. We might
-                                 * have returned with -EDEADLK and the
-                                 * owner released the lock while we
-                                 * were walking the pi chain.
-                                 */
-                                ret = 0;
-                                continue;
-                        }
-                        if (unlikely(ret))
-                                break;
-                }
-
                 raw_spin_unlock(&lock->wait_lock);
 
                 debug_rt_mutex_print_deadlock(waiter);
 
-                if (waiter->task)
-                        schedule_rt_mutex(lock);
+                schedule_rt_mutex(lock);
 
                 raw_spin_lock(&lock->wait_lock);
                 set_current_state(state);
@@ -698,12 +624,11 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state,
         int ret = 0;
 
         debug_rt_mutex_init_waiter(&waiter);
-        waiter.task = NULL;
 
         raw_spin_lock(&lock->wait_lock);
 
         /* Try to acquire the lock again: */
-        if (try_to_take_rt_mutex(lock)) {
+        if (try_to_take_rt_mutex(lock, current, NULL)) {
                 raw_spin_unlock(&lock->wait_lock);
                 return 0;
         }
@@ -717,12 +642,14 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state,
                         timeout->task = NULL;
         }
 
-        ret = __rt_mutex_slowlock(lock, state, timeout, &waiter,
-                                  detect_deadlock);
+        ret = task_blocks_on_rt_mutex(lock, &waiter, current, detect_deadlock);
+
+        if (likely(!ret))
+                ret = __rt_mutex_slowlock(lock, state, timeout, &waiter);
 
         set_current_state(TASK_RUNNING);
 
-        if (unlikely(waiter.task))
+        if (unlikely(ret))
                 remove_waiter(lock, &waiter);
 
         /*
@@ -737,14 +664,6 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state,
         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;
@@ -762,7 +681,7 @@ rt_mutex_slowtrylock(struct rt_mutex *lock)
 
         if (likely(rt_mutex_owner(lock) != current)) {
 
-                ret = try_to_take_rt_mutex(lock);
+                ret = try_to_take_rt_mutex(lock, current, NULL);
                 /*
                  * try_to_take_rt_mutex() sets the lock waiters
                  * bit unconditionally. Clean this up.
@@ -992,7 +911,7 @@ void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
 {
         __rt_mutex_init(lock, NULL);
         debug_rt_mutex_proxy_lock(lock, proxy_owner);
-        rt_mutex_set_owner(lock, proxy_owner, 0);
+        rt_mutex_set_owner(lock, proxy_owner);
         rt_mutex_deadlock_account_lock(lock, proxy_owner);
 }
 
@@ -1008,7 +927,7 @@ void rt_mutex_proxy_unlock(struct rt_mutex *lock,
                            struct task_struct *proxy_owner)
 {
         debug_rt_mutex_proxy_unlock(lock);
-        rt_mutex_set_owner(lock, NULL, 0);
+        rt_mutex_set_owner(lock, NULL);
         rt_mutex_deadlock_account_unlock(proxy_owner);
 }
 
@@ -1034,20 +953,14 @@ int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
 
         raw_spin_lock(&lock->wait_lock);
 
-        mark_rt_mutex_waiters(lock);
-
-        if (!rt_mutex_owner(lock) || try_to_steal_lock(lock, task)) {
-                /* We got the lock for task. */
-                debug_rt_mutex_lock(lock);
-                rt_mutex_set_owner(lock, task, 0);
+        if (try_to_take_rt_mutex(lock, task, NULL)) {
                 raw_spin_unlock(&lock->wait_lock);
-                rt_mutex_deadlock_account_lock(lock, task);
                 return 1;
         }
 
         ret = task_blocks_on_rt_mutex(lock, waiter, task, detect_deadlock);
 
-        if (ret && !waiter->task) {
+        if (ret && !rt_mutex_owner(lock)) {
                 /*
                  * Reset the return value. We might have
                  * returned with -EDEADLK and the owner
@@ -1056,6 +969,10 @@ int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
                  */
                 ret = 0;
         }
+
+        if (unlikely(ret))
+                remove_waiter(lock, waiter);
+
         raw_spin_unlock(&lock->wait_lock);
 
         debug_rt_mutex_print_deadlock(waiter);
@@ -1110,12 +1027,11 @@ int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
 
         set_current_state(TASK_INTERRUPTIBLE);
 
-        ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter,
-                                  detect_deadlock);
+        ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter);
 
         set_current_state(TASK_RUNNING);
 
-        if (unlikely(waiter->task))
+        if (unlikely(ret))
                 remove_waiter(lock, waiter);
 
         /*
@@ -1126,13 +1042,5 @@ int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
 
         raw_spin_unlock(&lock->wait_lock);
 
-        /*
-         * 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);
-
         return ret;
 }
diff --git a/kernel/rtmutex_common.h b/kernel/rtmutex_common.h
index 97a2f81866af..53a66c85261b 100644
--- a/kernel/rtmutex_common.h
+++ b/kernel/rtmutex_common.h
@@ -91,9 +91,8 @@ task_top_pi_waiter(struct task_struct *p)
 /*
  * lock->owner state tracking:
  */
-#define RT_MUTEX_OWNER_PENDING  1UL
-#define RT_MUTEX_HAS_WAITERS    2UL
-#define RT_MUTEX_OWNER_MASKALL  3UL
+#define RT_MUTEX_HAS_WAITERS    1UL
+#define RT_MUTEX_OWNER_MASKALL  1UL
 
 static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
 {
@@ -101,17 +100,6 @@ static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
                 ((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;
-}
-
 /*
  * PI-futex support (proxy locking functions, etc.):
  */
diff --git a/kernel/timer.c b/kernel/timer.c
index 33a67925d900..3503c17ac1d3 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -970,6 +970,25 @@ EXPORT_SYMBOL(try_to_del_timer_sync);
  * add_timer_on(). Upon exit the timer is not queued and the handler is
  * not running on any CPU.
  *
+ * Note: You must not hold locks that are held in interrupt context
+ *   while calling this function. Even if the lock has nothing to do
+ *   with the timer in question.  Here's why:
+ *
+ *    CPU0                             CPU1
+ *    ----                             ----
+ *                                   <SOFTIRQ>
+ *                                   call_timer_fn();
+ *                                     base->running_timer = mytimer;
+ *  spin_lock_irq(somelock);
+ *                                     <IRQ>
+ *                                        spin_lock(somelock);
+ *  del_timer_sync(mytimer);
+ *   while (base->running_timer == mytimer);
+ *
+ * Now del_timer_sync() will never return and never release somelock.
+ * The interrupt on the other CPU is waiting to grab somelock but
+ * it has interrupted the softirq that CPU0 is waiting to finish.
+ *
  * The function returns whether it has deactivated a pending timer or not.
  */
 int del_timer_sync(struct timer_list *timer)
@@ -977,6 +996,10 @@ int del_timer_sync(struct timer_list *timer)
 #ifdef CONFIG_LOCKDEP
         unsigned long flags;
 
+        /*
+         * If lockdep gives a backtrace here, please reference
+         * the synchronization rules above.
+         */
         local_irq_save(flags);
         lock_map_acquire(&timer->lockdep_map);
         lock_map_release(&timer->lockdep_map);