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Diffstat (limited to 'nptl/pthread_mutex_trylock.c')
-rw-r--r--nptl/pthread_mutex_trylock.c327
1 files changed, 11 insertions, 316 deletions
diff --git a/nptl/pthread_mutex_trylock.c b/nptl/pthread_mutex_trylock.c
index 66aca8e4b2..7008af3d97 100644
--- a/nptl/pthread_mutex_trylock.c
+++ b/nptl/pthread_mutex_trylock.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2002, 2003, 2005, 2006, 2007 Free Software Foundation, Inc.
+/* Copyright (C) 2002, 2003 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
@@ -17,9 +17,7 @@
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>
@@ -28,13 +26,13 @@ int
__pthread_mutex_trylock (mutex)
pthread_mutex_t *mutex;
{
- int oldval;
- pid_t id = THREAD_GETMEM (THREAD_SELF, tid);
+ pid_t id;
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)
{
@@ -58,323 +56,20 @@ __pthread_mutex_trylock (mutex)
break;
case PTHREAD_MUTEX_ERRORCHECK_NP:
- /* Check whether we already hold the mutex. */
- if (__builtin_expect (mutex->__data.__owner == id, 0))
- return EDEADLK;
-
- /* FALLTHROUGH */
-
+ /* 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)
- 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
+ if (lll_mutex_trylock (mutex->__data.__lock) == 0)
{
- again:
- if ((oldval & FUTEX_OWNER_DIED) != 0)
- {
- /* The previous owner died. Try locking the mutex. */
- int newval = id | (oldval & FUTEX_WAITERS);
-
- 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;
- }
+ /* Record the ownership. */
+ mutex->__data.__owner = THREAD_GETMEM (THREAD_SELF, tid);
+ ++mutex->__data.__nusers;
- 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;
- }
+ return 0;
}
- 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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