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

Browse Source 
* '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
This commit is contained in:
Linus Torvalds
2011-03-15 18:28:30 -07:00
parent b80cd62b7d dbebbfbb16
commit 0586bed3e8
40 changed files with 228 additions and 816 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
kernel/cred.c
View File

@ -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

22
kernel/futex.c
View File

@ -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 "

1
kernel/rtmutex-debug.c
View File

@ -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));
}

40
kernel/rtmutex-tester.c
View File

@ -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]);

318
kernel/rtmutex.c
View File

@ -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.
*
* (*) 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.
* (*) 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 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 */
@ -295,79 +298,17 @@ static int rt_mutex_adjust_prio_chain(struct 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 *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;
}

16
kernel/rtmutex_common.h
View File

@ -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.):
*/

23
kernel/timer.c
View File

@ -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);