diff options
Diffstat (limited to 'libpthread/nptl/pthread_mutex_trylock.c')
| -rw-r--r-- | libpthread/nptl/pthread_mutex_trylock.c | 334 |
1 files changed, 320 insertions, 14 deletions
diff --git a/libpthread/nptl/pthread_mutex_trylock.c b/libpthread/nptl/pthread_mutex_trylock.c index 2eb88db53..5555afcb7 100644 --- a/libpthread/nptl/pthread_mutex_trylock.c +++ b/libpthread/nptl/pthread_mutex_trylock.c @@ -1,4 +1,4 @@ -/* Copyright (C) 2002, 2003 Free Software Foundation, Inc. +/* Copyright (C) 2002, 2003, 2005-2007, 2008 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper <drepper@redhat.com>, 2002. @@ -17,21 +17,25 @@ 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> int -__pthread_mutex_trylock (pthread_mutex_t *mutex) +__pthread_mutex_trylock ( + 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)) + switch (__builtin_expect (PTHREAD_MUTEX_TYPE (mutex), + 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) { @@ -44,7 +48,7 @@ __pthread_mutex_trylock (pthread_mutex_t *mutex) return 0; } - if (lll_mutex_trylock (mutex->__data.__lock) == 0) + if (lll_trylock (mutex->__data.__lock) == 0) { /* Record the ownership. */ mutex->__data.__owner = id; @@ -55,20 +59,322 @@ __pthread_mutex_trylock (pthread_mutex_t *mutex) break; case PTHREAD_MUTEX_ERRORCHECK_NP: - /* Error checking mutex. We do not check for deadlocks. */ - default: - /* Correct code cannot set any other type. */ case PTHREAD_MUTEX_TIMED_NP: case PTHREAD_MUTEX_ADAPTIVE_NP: /* Normal mutex. */ - if (lll_mutex_trylock (mutex->__data.__lock) == 0) + if (lll_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)) + { + int kind = PTHREAD_MUTEX_TYPE (mutex); + if (kind == PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP) + { + THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, + NULL); + return EDEADLK; + } + + if (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_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_unlock (mutex->__data.__lock, + PTHREAD_ROBUST_MUTEX_PSHARED (mutex)); + 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. */ + int private = (robust + ? PTHREAD_ROBUST_MUTEX_PSHARED (mutex) + : PTHREAD_MUTEX_PSHARED (mutex)); + INTERNAL_SYSCALL_DECL (__err); + int e = INTERNAL_SYSCALL (futex, __err, 4, &mutex->__data.__lock, + __lll_private_flag (FUTEX_TRYLOCK_PI, + private), 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, + __lll_private_flag (FUTEX_UNLOCK_PI, + PTHREAD_ROBUST_MUTEX_PSHARED (mutex)), + 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; |