-/* Copyright (C) 2002, 2003 Free Software Foundation, Inc.
+/* Copyright (C) 2002, 2003, 2005, 2006, 2007 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
+#include <assert.h>
#include <errno.h>
+#include <stdlib.h>
#include "pthreadP.h"
#include <lowlevellock.h>
__pthread_mutex_trylock (mutex)
pthread_mutex_t *mutex;
{
- pid_t id;
+ int oldval;
+ pid_t id = THREAD_GETMEM (THREAD_SELF, tid);
switch (__builtin_expect (mutex->__data.__kind, PTHREAD_MUTEX_TIMED_NP))
{
/* Recursive mutex. */
case PTHREAD_MUTEX_RECURSIVE_NP:
- id = THREAD_GETMEM (THREAD_SELF, tid);
/* Check whether we already hold the mutex. */
if (mutex->__data.__owner == id)
{
break;
case PTHREAD_MUTEX_ERRORCHECK_NP:
- /* Error checking mutex. We do not check for deadlocks. */
- default:
- /* Correct code cannot set any other type. */
+ /* Check whether we already hold the mutex. */
+ if (__builtin_expect (mutex->__data.__owner == id, 0))
+ return EDEADLK;
+
+ /* FALLTHROUGH */
+
case PTHREAD_MUTEX_TIMED_NP:
case PTHREAD_MUTEX_ADAPTIVE_NP:
/* Normal mutex. */
- if (lll_mutex_trylock (mutex->__data.__lock) == 0)
+ if (lll_mutex_trylock (mutex->__data.__lock) != 0)
+ break;
+
+ /* Record the ownership. */
+ mutex->__data.__owner = id;
+ ++mutex->__data.__nusers;
+
+ return 0;
+
+
+ case PTHREAD_MUTEX_ROBUST_RECURSIVE_NP:
+ case PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP:
+ case PTHREAD_MUTEX_ROBUST_NORMAL_NP:
+ case PTHREAD_MUTEX_ROBUST_ADAPTIVE_NP:
+ THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
+ &mutex->__data.__list.__next);
+
+ oldval = mutex->__data.__lock;
+ do
{
- /* Record the ownership. */
- mutex->__data.__owner = THREAD_GETMEM (THREAD_SELF, tid);
- ++mutex->__data.__nusers;
+ again:
+ if ((oldval & FUTEX_OWNER_DIED) != 0)
+ {
+ /* The previous owner died. Try locking the mutex. */
+ int newval = id | (oldval & FUTEX_WAITERS);
- return 0;
+ newval
+ = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
+ newval, oldval);
+
+ if (newval != oldval)
+ {
+ oldval = newval;
+ goto again;
+ }
+
+ /* We got the mutex. */
+ mutex->__data.__count = 1;
+ /* But it is inconsistent unless marked otherwise. */
+ mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;
+
+ ENQUEUE_MUTEX (mutex);
+ THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
+
+ /* Note that we deliberately exist here. If we fall
+ through to the end of the function __nusers would be
+ incremented which is not correct because the old
+ owner has to be discounted. */
+ return EOWNERDEAD;
+ }
+
+ /* Check whether we already hold the mutex. */
+ if (__builtin_expect ((oldval & FUTEX_TID_MASK) == id, 0))
+ {
+ if (mutex->__data.__kind
+ == PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP)
+ {
+ THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
+ NULL);
+ return EDEADLK;
+ }
+
+ if (mutex->__data.__kind
+ == PTHREAD_MUTEX_ROBUST_RECURSIVE_NP)
+ {
+ THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
+ NULL);
+
+ /* Just bump the counter. */
+ if (__builtin_expect (mutex->__data.__count + 1 == 0, 0))
+ /* Overflow of the counter. */
+ return EAGAIN;
+
+ ++mutex->__data.__count;
+
+ return 0;
+ }
+ }
+
+ oldval = lll_robust_mutex_trylock (mutex->__data.__lock, id);
+ if (oldval != 0 && (oldval & FUTEX_OWNER_DIED) == 0)
+ {
+ THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
+
+ return EBUSY;
+ }
+
+ if (__builtin_expect (mutex->__data.__owner
+ == PTHREAD_MUTEX_NOTRECOVERABLE, 0))
+ {
+ /* This mutex is now not recoverable. */
+ mutex->__data.__count = 0;
+ if (oldval == id)
+ lll_mutex_unlock (mutex->__data.__lock);
+ THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
+ return ENOTRECOVERABLE;
+ }
}
+ while ((oldval & FUTEX_OWNER_DIED) != 0);
+
+ ENQUEUE_MUTEX (mutex);
+ THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
+
+ mutex->__data.__owner = id;
+ ++mutex->__data.__nusers;
+ mutex->__data.__count = 1;
+
+ return 0;
+
+ case PTHREAD_MUTEX_PI_RECURSIVE_NP:
+ case PTHREAD_MUTEX_PI_ERRORCHECK_NP:
+ case PTHREAD_MUTEX_PI_NORMAL_NP:
+ case PTHREAD_MUTEX_PI_ADAPTIVE_NP:
+ case PTHREAD_MUTEX_PI_ROBUST_RECURSIVE_NP:
+ case PTHREAD_MUTEX_PI_ROBUST_ERRORCHECK_NP:
+ case PTHREAD_MUTEX_PI_ROBUST_NORMAL_NP:
+ case PTHREAD_MUTEX_PI_ROBUST_ADAPTIVE_NP:
+ {
+ int kind = mutex->__data.__kind & PTHREAD_MUTEX_KIND_MASK_NP;
+ int robust = mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP;
+
+ if (robust)
+ /* Note: robust PI futexes are signaled by setting bit 0. */
+ THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
+ (void *) (((uintptr_t) &mutex->__data.__list.__next)
+ | 1));
+
+ oldval = mutex->__data.__lock;
+
+ /* Check whether we already hold the mutex. */
+ if (__builtin_expect ((oldval & FUTEX_TID_MASK) == id, 0))
+ {
+ if (kind == PTHREAD_MUTEX_ERRORCHECK_NP)
+ {
+ THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
+ return EDEADLK;
+ }
+
+ if (kind == PTHREAD_MUTEX_RECURSIVE_NP)
+ {
+ THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
+
+ /* Just bump the counter. */
+ if (__builtin_expect (mutex->__data.__count + 1 == 0, 0))
+ /* Overflow of the counter. */
+ return EAGAIN;
+
+ ++mutex->__data.__count;
+
+ return 0;
+ }
+ }
+
+ oldval
+ = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
+ id, 0);
+
+ if (oldval != 0)
+ {
+ if ((oldval & FUTEX_OWNER_DIED) == 0)
+ {
+ THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
+
+ return EBUSY;
+ }
+
+ assert (robust);
+
+ /* The mutex owner died. The kernel will now take care of
+ everything. */
+ INTERNAL_SYSCALL_DECL (__err);
+ int e = INTERNAL_SYSCALL (futex, __err, 4, &mutex->__data.__lock,
+ FUTEX_TRYLOCK_PI, 0, 0);
+
+ if (INTERNAL_SYSCALL_ERROR_P (e, __err)
+ && INTERNAL_SYSCALL_ERRNO (e, __err) == EWOULDBLOCK)
+ {
+ THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
+
+ return EBUSY;
+ }
+
+ oldval = mutex->__data.__lock;
+ }
+
+ if (__builtin_expect (oldval & FUTEX_OWNER_DIED, 0))
+ {
+ atomic_and (&mutex->__data.__lock, ~FUTEX_OWNER_DIED);
+
+ /* We got the mutex. */
+ mutex->__data.__count = 1;
+ /* But it is inconsistent unless marked otherwise. */
+ mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;
+
+ ENQUEUE_MUTEX (mutex);
+ THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
+
+ /* Note that we deliberately exit here. If we fall
+ through to the end of the function __nusers would be
+ incremented which is not correct because the old owner
+ has to be discounted. */
+ return EOWNERDEAD;
+ }
+
+ if (robust
+ && __builtin_expect (mutex->__data.__owner
+ == PTHREAD_MUTEX_NOTRECOVERABLE, 0))
+ {
+ /* This mutex is now not recoverable. */
+ mutex->__data.__count = 0;
+
+ INTERNAL_SYSCALL_DECL (__err);
+ INTERNAL_SYSCALL (futex, __err, 4, &mutex->__data.__lock,
+ FUTEX_UNLOCK_PI, 0, 0);
+
+ THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
+ return ENOTRECOVERABLE;
+ }
+
+ if (robust)
+ {
+ ENQUEUE_MUTEX_PI (mutex);
+ THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
+ }
+
+ mutex->__data.__owner = id;
+ ++mutex->__data.__nusers;
+ mutex->__data.__count = 1;
+
+ return 0;
+ }
+
+ case PTHREAD_MUTEX_PP_RECURSIVE_NP:
+ case PTHREAD_MUTEX_PP_ERRORCHECK_NP:
+ case PTHREAD_MUTEX_PP_NORMAL_NP:
+ case PTHREAD_MUTEX_PP_ADAPTIVE_NP:
+ {
+ int kind = mutex->__data.__kind & PTHREAD_MUTEX_KIND_MASK_NP;
+
+ oldval = mutex->__data.__lock;
+
+ /* Check whether we already hold the mutex. */
+ if (mutex->__data.__owner == id)
+ {
+ if (kind == PTHREAD_MUTEX_ERRORCHECK_NP)
+ return EDEADLK;
+
+ if (kind == PTHREAD_MUTEX_RECURSIVE_NP)
+ {
+ /* Just bump the counter. */
+ if (__builtin_expect (mutex->__data.__count + 1 == 0, 0))
+ /* Overflow of the counter. */
+ return EAGAIN;
+
+ ++mutex->__data.__count;
+
+ return 0;
+ }
+ }
+
+ int oldprio = -1, ceilval;
+ do
+ {
+ int ceiling = (oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK)
+ >> PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
+
+ if (__pthread_current_priority () > ceiling)
+ {
+ if (oldprio != -1)
+ __pthread_tpp_change_priority (oldprio, -1);
+ return EINVAL;
+ }
+
+ int retval = __pthread_tpp_change_priority (oldprio, ceiling);
+ if (retval)
+ return retval;
+
+ ceilval = ceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
+ oldprio = ceiling;
+
+ oldval
+ = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
+ ceilval | 1, ceilval);
+
+ if (oldval == ceilval)
+ break;
+ }
+ while ((oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK) != ceilval);
+
+ if (oldval != ceilval)
+ {
+ __pthread_tpp_change_priority (oldprio, -1);
+ break;
+ }
+
+ assert (mutex->__data.__owner == 0);
+ /* Record the ownership. */
+ mutex->__data.__owner = id;
+ ++mutex->__data.__nusers;
+ mutex->__data.__count = 1;
+
+ return 0;
+ }
+ break;
+
+ default:
+ /* Correct code cannot set any other type. */
+ return EINVAL;
}
return EBUSY;
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