* Copyright (C) 2005-2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
* Copyright (C) 2005 Kihon Technologies Inc., Steven Rostedt
* Copyright (C) 2006 Esben Nielsen
+ *
+ * See Documentation/rt-mutex-design.txt for details.
*/
#include <linux/spinlock.h>
#include <linux/module.h>
* 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,
+static int rt_mutex_adjust_prio_chain(struct task_struct *task,
int deadlock_detect,
struct rt_mutex *orig_lock,
- struct rt_mutex_waiter *orig_waiter
- __IP_DECL__)
+ struct rt_mutex_waiter *orig_waiter,
+ struct task_struct *top_task)
{
struct rt_mutex *lock;
struct rt_mutex_waiter *waiter, *top_waiter = orig_waiter;
prev_max = max_lock_depth;
printk(KERN_WARNING "Maximum lock depth %d reached "
"task: %s (%d)\n", max_lock_depth,
- current->comm, current->pid);
+ top_task->comm, top_task->pid);
}
put_task_struct(task);
}
/* Deadlock detection */
- if (lock == orig_lock || rt_mutex_owner(lock) == current) {
+ if (lock == orig_lock || rt_mutex_owner(lock) == top_task) {
debug_rt_mutex_deadlock(deadlock_detect, orig_waiter, lock);
spin_unlock(&lock->wait_lock);
ret = deadlock_detect ? -EDEADLK : 0;
/* Grab the next task */
task = rt_mutex_owner(lock);
+ get_task_struct(task);
spin_lock_irqsave(&task->pi_lock, flags);
if (waiter == rt_mutex_top_waiter(lock)) {
__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_irqrestore(&task->pi_lock, flags);
out_put_task:
put_task_struct(task);
+
return ret;
}
*
* Must be called with lock->wait_lock held.
*/
-static int try_to_take_rt_mutex(struct rt_mutex *lock __IP_DECL__)
+static int try_to_take_rt_mutex(struct rt_mutex *lock)
{
/*
* We have to be careful here if the atomic speedups are
return 0;
/* We got the lock. */
- debug_rt_mutex_lock(lock __IP__);
+ debug_rt_mutex_lock(lock);
rt_mutex_set_owner(lock, current, 0);
*/
static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
struct rt_mutex_waiter *waiter,
- int detect_deadlock
- __IP_DECL__)
+ int detect_deadlock)
{
+ struct task_struct *owner = rt_mutex_owner(lock);
struct rt_mutex_waiter *top_waiter = waiter;
- task_t *owner = rt_mutex_owner(lock);
- int boost = 0, res;
unsigned long flags;
+ int chain_walk = 0, res;
spin_lock_irqsave(¤t->pi_lock, flags);
__rt_mutex_adjust_prio(current);
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);
- }
+ if (owner->pi_blocked_on)
+ chain_walk = 1;
spin_unlock_irqrestore(&owner->pi_lock, flags);
}
- if (!boost)
+ else if (debug_rt_mutex_detect_deadlock(waiter, detect_deadlock))
+ chain_walk = 1;
+
+ if (!chain_walk)
return 0;
+ /*
+ * The owner can't disappear while holding a lock,
+ * so the owner struct is protected by wait_lock.
+ * Gets dropped in rt_mutex_adjust_prio_chain()!
+ */
+ get_task_struct(owner);
+
spin_unlock(&lock->wait_lock);
- res = rt_mutex_adjust_prio_chain(owner, detect_deadlock, lock,
- waiter __IP__);
+ res = rt_mutex_adjust_prio_chain(owner, detect_deadlock, lock, waiter,
+ current);
spin_lock(&lock->wait_lock);
* Must be called with lock->wait_lock held
*/
static void remove_waiter(struct rt_mutex *lock,
- struct rt_mutex_waiter *waiter __IP_DECL__)
+ struct rt_mutex_waiter *waiter)
{
int first = (waiter == rt_mutex_top_waiter(lock));
- int boost = 0;
- task_t *owner = rt_mutex_owner(lock);
+ struct task_struct *owner = rt_mutex_owner(lock);
unsigned long flags;
+ int chain_walk = 0;
spin_lock_irqsave(¤t->pi_lock, flags);
plist_del(&waiter->list_entry, &lock->wait_list);
}
__rt_mutex_adjust_prio(owner);
- if (owner->pi_blocked_on) {
- boost = 1;
- get_task_struct(owner);
- }
+ if (owner->pi_blocked_on)
+ chain_walk = 1;
+
spin_unlock_irqrestore(&owner->pi_lock, flags);
}
WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
- if (!boost)
+ if (!chain_walk)
return;
+ /* gets dropped in rt_mutex_adjust_prio_chain()! */
+ get_task_struct(owner);
+
spin_unlock(&lock->wait_lock);
- rt_mutex_adjust_prio_chain(owner, 0, lock, NULL __IP__);
+ rt_mutex_adjust_prio_chain(owner, 0, lock, NULL, current);
spin_lock(&lock->wait_lock);
}
+/*
+ * Recheck the pi chain, in case we got a priority setting
+ *
+ * Called from sched_setscheduler
+ */
+void rt_mutex_adjust_pi(struct task_struct *task)
+{
+ struct rt_mutex_waiter *waiter;
+ unsigned long flags;
+
+ spin_lock_irqsave(&task->pi_lock, flags);
+
+ waiter = task->pi_blocked_on;
+ if (!waiter || waiter->list_entry.prio == task->prio) {
+ spin_unlock_irqrestore(&task->pi_lock, flags);
+ return;
+ }
+
+ spin_unlock_irqrestore(&task->pi_lock, flags);
+
+ /* gets dropped in rt_mutex_adjust_prio_chain()! */
+ get_task_struct(task);
+ rt_mutex_adjust_prio_chain(task, 0, NULL, NULL, task);
+}
+
/*
* 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__)
+ int detect_deadlock)
{
struct rt_mutex_waiter waiter;
int ret = 0;
spin_lock(&lock->wait_lock);
/* Try to acquire the lock again: */
- if (try_to_take_rt_mutex(lock __IP__)) {
+ if (try_to_take_rt_mutex(lock)) {
spin_unlock(&lock->wait_lock);
return 0;
}
for (;;) {
/* Try to acquire the lock: */
- if (try_to_take_rt_mutex(lock __IP__))
+ if (try_to_take_rt_mutex(lock))
break;
/*
*/
if (!waiter.task) {
ret = task_blocks_on_rt_mutex(lock, &waiter,
- detect_deadlock __IP__);
+ detect_deadlock);
/*
* If we got woken up by the owner then start loop
* all over without going into schedule to try
if (unlikely(ret))
break;
}
+
spin_unlock(&lock->wait_lock);
debug_rt_mutex_print_deadlock(&waiter);
set_current_state(TASK_RUNNING);
if (unlikely(waiter.task))
- remove_waiter(lock, &waiter __IP__);
+ remove_waiter(lock, &waiter);
/*
* try_to_take_rt_mutex() sets the waiter bit
* Slow path try-lock function:
*/
static inline int
-rt_mutex_slowtrylock(struct rt_mutex *lock __IP_DECL__)
+rt_mutex_slowtrylock(struct rt_mutex *lock)
{
int ret = 0;
if (likely(rt_mutex_owner(lock) != current)) {
- ret = try_to_take_rt_mutex(lock __IP__);
+ ret = try_to_take_rt_mutex(lock);
/*
* try_to_take_rt_mutex() sets the lock waiters
* bit unconditionally. Clean this up.
int detect_deadlock,
int (*slowfn)(struct rt_mutex *lock, int state,
struct hrtimer_sleeper *timeout,
- int detect_deadlock __IP_DECL__))
+ int detect_deadlock))
{
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__);
+ return slowfn(lock, state, NULL, detect_deadlock);
}
static inline int
struct hrtimer_sleeper *timeout, int detect_deadlock,
int (*slowfn)(struct rt_mutex *lock, int state,
struct hrtimer_sleeper *timeout,
- int detect_deadlock __IP_DECL__))
+ int detect_deadlock))
{
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__);
+ return slowfn(lock, state, timeout, detect_deadlock);
}
static inline int
rt_mutex_fasttrylock(struct rt_mutex *lock,
- int (*slowfn)(struct rt_mutex *lock __IP_DECL__))
+ int (*slowfn)(struct rt_mutex *lock))
{
if (likely(rt_mutex_cmpxchg(lock, NULL, current))) {
rt_mutex_deadlock_account_lock(lock, current);
return 1;
}
- return slowfn(lock __RET_IP__);
+ return slowfn(lock);
}
static inline void
debug_rt_mutex_init(lock, name);
}
EXPORT_SYMBOL_GPL(__rt_mutex_init);
+
+/**
+ * rt_mutex_init_proxy_locked - initialize and lock a rt_mutex on behalf of a
+ * proxy owner
+ *
+ * @lock: the rt_mutex to be locked
+ * @proxy_owner:the task to set as owner
+ *
+ * No locking. Caller has to do serializing itself
+ * Special API call for PI-futex support
+ */
+void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
+ struct task_struct *proxy_owner)
+{
+ __rt_mutex_init(lock, NULL);
+ debug_rt_mutex_proxy_lock(lock, proxy_owner);
+ rt_mutex_set_owner(lock, proxy_owner, 0);
+ rt_mutex_deadlock_account_lock(lock, proxy_owner);
+}
+
+/**
+ * rt_mutex_proxy_unlock - release a lock on behalf of owner
+ *
+ * @lock: the rt_mutex to be locked
+ *
+ * No locking. Caller has to do serializing itself
+ * Special API call for PI-futex support
+ */
+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_deadlock_account_unlock(proxy_owner);
+}
+
+/**
+ * rt_mutex_next_owner - return the next owner of the lock
+ *
+ * @lock: the rt lock query
+ *
+ * Returns the next owner of the lock or NULL
+ *
+ * Caller has to serialize against other accessors to the lock
+ * itself.
+ *
+ * Special API call for PI-futex support
+ */
+struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock)
+{
+ if (!rt_mutex_has_waiters(lock))
+ return NULL;
+
+ return rt_mutex_top_waiter(lock)->task;
+}
git.openpandora.org / pandora-kernel.git / blobdiff