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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 19:16:34 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 19:16:34 +0000 |
commit | a398d2c2b5fd6ab0545d8bb019f9a970b2309404 (patch) | |
tree | 272fc7ab226258d7ceddee12c8c682c8e711c2b0 /lib/glthread/lock.c | |
parent | Initial commit. (diff) | |
download | parted-a398d2c2b5fd6ab0545d8bb019f9a970b2309404.tar.xz parted-a398d2c2b5fd6ab0545d8bb019f9a970b2309404.zip |
Adding upstream version 3.6.upstream/3.6upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | lib/glthread/lock.c | 749 |
1 files changed, 749 insertions, 0 deletions
diff --git a/lib/glthread/lock.c b/lib/glthread/lock.c new file mode 100644 index 0000000..82fb755 --- /dev/null +++ b/lib/glthread/lock.c @@ -0,0 +1,749 @@ +/* Locking in multithreaded situations. + Copyright (C) 2005-2023 Free Software Foundation, Inc. + + This file is free software: you can redistribute it and/or modify + it under the terms of the GNU Lesser General Public License as + published by the Free Software Foundation; either version 2.1 of the + License, or (at your option) any later version. + + This file is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with this program. If not, see <https://www.gnu.org/licenses/>. */ + +/* Written by Bruno Haible <bruno@clisp.org>, 2005. + Based on GCC's gthr-posix.h, gthr-posix95.h. */ + +#include <config.h> + +#include "glthread/lock.h" + +/* ========================================================================= */ + +#if USE_ISOC_THREADS || USE_ISOC_AND_POSIX_THREADS + +/* -------------------------- gl_lock_t datatype -------------------------- */ + +int +glthread_lock_init (gl_lock_t *lock) +{ + if (mtx_init (&lock->mutex, mtx_plain) != thrd_success) + return ENOMEM; + lock->init_needed = 0; + return 0; +} + +int +glthread_lock_lock (gl_lock_t *lock) +{ + if (lock->init_needed) + call_once (&lock->init_once, lock->init_func); + if (mtx_lock (&lock->mutex) != thrd_success) + return EAGAIN; + return 0; +} + +int +glthread_lock_unlock (gl_lock_t *lock) +{ + if (lock->init_needed) + call_once (&lock->init_once, lock->init_func); + if (mtx_unlock (&lock->mutex) != thrd_success) + return EINVAL; + return 0; +} + +int +glthread_lock_destroy (gl_lock_t *lock) +{ + if (lock->init_needed) + call_once (&lock->init_once, lock->init_func); + mtx_destroy (&lock->mutex); + return 0; +} + +/* ------------------------- gl_rwlock_t datatype ------------------------- */ + +int +glthread_rwlock_init (gl_rwlock_t *lock) +{ + if (mtx_init (&lock->lock, mtx_plain) != thrd_success + || cnd_init (&lock->waiting_readers) != thrd_success + || cnd_init (&lock->waiting_writers) != thrd_success) + return ENOMEM; + lock->waiting_writers_count = 0; + lock->runcount = 0; + lock->init_needed = 0; + return 0; +} + +int +glthread_rwlock_rdlock (gl_rwlock_t *lock) +{ + if (lock->init_needed) + call_once (&lock->init_once, lock->init_func); + if (mtx_lock (&lock->lock) != thrd_success) + return EAGAIN; + /* Test whether only readers are currently running, and whether the runcount + field will not overflow, and whether no writer is waiting. The latter + condition is because POSIX recommends that "write locks shall take + precedence over read locks", to avoid "writer starvation". */ + while (!(lock->runcount + 1 > 0 && lock->waiting_writers_count == 0)) + { + /* This thread has to wait for a while. Enqueue it among the + waiting_readers. */ + if (cnd_wait (&lock->waiting_readers, &lock->lock) != thrd_success) + { + mtx_unlock (&lock->lock); + return EINVAL; + } + } + lock->runcount++; + if (mtx_unlock (&lock->lock) != thrd_success) + return EINVAL; + return 0; +} + +int +glthread_rwlock_wrlock (gl_rwlock_t *lock) +{ + if (lock->init_needed) + call_once (&lock->init_once, lock->init_func); + if (mtx_lock (&lock->lock) != thrd_success) + return EAGAIN; + /* Test whether no readers or writers are currently running. */ + while (!(lock->runcount == 0)) + { + /* This thread has to wait for a while. Enqueue it among the + waiting_writers. */ + lock->waiting_writers_count++; + if (cnd_wait (&lock->waiting_writers, &lock->lock) != thrd_success) + { + lock->waiting_writers_count--; + mtx_unlock (&lock->lock); + return EINVAL; + } + lock->waiting_writers_count--; + } + lock->runcount--; /* runcount becomes -1 */ + if (mtx_unlock (&lock->lock) != thrd_success) + return EINVAL; + return 0; +} + +int +glthread_rwlock_unlock (gl_rwlock_t *lock) +{ + if (lock->init_needed) + call_once (&lock->init_once, lock->init_func); + if (mtx_lock (&lock->lock) != thrd_success) + return EAGAIN; + if (lock->runcount < 0) + { + /* Drop a writer lock. */ + if (!(lock->runcount == -1)) + { + mtx_unlock (&lock->lock); + return EINVAL; + } + lock->runcount = 0; + } + else + { + /* Drop a reader lock. */ + if (!(lock->runcount > 0)) + { + mtx_unlock (&lock->lock); + return EINVAL; + } + lock->runcount--; + } + if (lock->runcount == 0) + { + /* POSIX recommends that "write locks shall take precedence over read + locks", to avoid "writer starvation". */ + if (lock->waiting_writers_count > 0) + { + /* Wake up one of the waiting writers. */ + if (cnd_signal (&lock->waiting_writers) != thrd_success) + { + mtx_unlock (&lock->lock); + return EINVAL; + } + } + else + { + /* Wake up all waiting readers. */ + if (cnd_broadcast (&lock->waiting_readers) != thrd_success) + { + mtx_unlock (&lock->lock); + return EINVAL; + } + } + } + if (mtx_unlock (&lock->lock) != thrd_success) + return EINVAL; + return 0; +} + +int +glthread_rwlock_destroy (gl_rwlock_t *lock) +{ + if (lock->init_needed) + call_once (&lock->init_once, lock->init_func); + mtx_destroy (&lock->lock); + cnd_destroy (&lock->waiting_readers); + cnd_destroy (&lock->waiting_writers); + return 0; +} + +/* --------------------- gl_recursive_lock_t datatype --------------------- */ + +int +glthread_recursive_lock_init (gl_recursive_lock_t *lock) +{ + if (mtx_init (&lock->mutex, mtx_plain | mtx_recursive) != thrd_success) + return ENOMEM; + lock->init_needed = 0; + return 0; +} + +int +glthread_recursive_lock_lock (gl_recursive_lock_t *lock) +{ + if (lock->init_needed) + call_once (&lock->init_once, lock->init_func); + if (mtx_lock (&lock->mutex) != thrd_success) + return EAGAIN; + return 0; +} + +int +glthread_recursive_lock_unlock (gl_recursive_lock_t *lock) +{ + if (lock->init_needed) + call_once (&lock->init_once, lock->init_func); + if (mtx_unlock (&lock->mutex) != thrd_success) + return EINVAL; + return 0; +} + +int +glthread_recursive_lock_destroy (gl_recursive_lock_t *lock) +{ + if (lock->init_needed) + call_once (&lock->init_once, lock->init_func); + mtx_destroy (&lock->mutex); + return 0; +} + +/* -------------------------- gl_once_t datatype -------------------------- */ + +#endif + +/* ========================================================================= */ + +#if USE_POSIX_THREADS + +/* -------------------------- gl_lock_t datatype -------------------------- */ + +/* ------------------------- gl_rwlock_t datatype ------------------------- */ + +# if HAVE_PTHREAD_RWLOCK && (HAVE_PTHREAD_RWLOCK_RDLOCK_PREFER_WRITER || (defined PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP && (__GNU_LIBRARY__ > 1))) + +# if defined PTHREAD_RWLOCK_INITIALIZER || defined PTHREAD_RWLOCK_INITIALIZER_NP + +# if !HAVE_PTHREAD_RWLOCK_RDLOCK_PREFER_WRITER + /* glibc with bug https://sourceware.org/bugzilla/show_bug.cgi?id=13701 */ + +int +glthread_rwlock_init_for_glibc (pthread_rwlock_t *lock) +{ + pthread_rwlockattr_t attributes; + int err; + + err = pthread_rwlockattr_init (&attributes); + if (err != 0) + return err; + /* Note: PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP is the only value that + causes the writer to be preferred. PTHREAD_RWLOCK_PREFER_WRITER_NP does not + do this; see + http://man7.org/linux/man-pages/man3/pthread_rwlockattr_setkind_np.3.html */ + err = pthread_rwlockattr_setkind_np (&attributes, + PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP); + if (err == 0) + err = pthread_rwlock_init(lock, &attributes); + /* pthread_rwlockattr_destroy always returns 0. It cannot influence the + return value. */ + pthread_rwlockattr_destroy (&attributes); + return err; +} + +# endif +# else + +int +glthread_rwlock_init_multithreaded (gl_rwlock_t *lock) +{ + int err; + + err = pthread_rwlock_init (&lock->rwlock, NULL); + if (err != 0) + return err; + lock->initialized = 1; + return 0; +} + +int +glthread_rwlock_rdlock_multithreaded (gl_rwlock_t *lock) +{ + if (!lock->initialized) + { + int err; + + err = pthread_mutex_lock (&lock->guard); + if (err != 0) + return err; + if (!lock->initialized) + { + err = glthread_rwlock_init_multithreaded (lock); + if (err != 0) + { + pthread_mutex_unlock (&lock->guard); + return err; + } + } + err = pthread_mutex_unlock (&lock->guard); + if (err != 0) + return err; + } + return pthread_rwlock_rdlock (&lock->rwlock); +} + +int +glthread_rwlock_wrlock_multithreaded (gl_rwlock_t *lock) +{ + if (!lock->initialized) + { + int err; + + err = pthread_mutex_lock (&lock->guard); + if (err != 0) + return err; + if (!lock->initialized) + { + err = glthread_rwlock_init_multithreaded (lock); + if (err != 0) + { + pthread_mutex_unlock (&lock->guard); + return err; + } + } + err = pthread_mutex_unlock (&lock->guard); + if (err != 0) + return err; + } + return pthread_rwlock_wrlock (&lock->rwlock); +} + +int +glthread_rwlock_unlock_multithreaded (gl_rwlock_t *lock) +{ + if (!lock->initialized) + return EINVAL; + return pthread_rwlock_unlock (&lock->rwlock); +} + +int +glthread_rwlock_destroy_multithreaded (gl_rwlock_t *lock) +{ + int err; + + if (!lock->initialized) + return EINVAL; + err = pthread_rwlock_destroy (&lock->rwlock); + if (err != 0) + return err; + lock->initialized = 0; + return 0; +} + +# endif + +# else + +int +glthread_rwlock_init_multithreaded (gl_rwlock_t *lock) +{ + int err; + + err = pthread_mutex_init (&lock->lock, NULL); + if (err != 0) + return err; + err = pthread_cond_init (&lock->waiting_readers, NULL); + if (err != 0) + return err; + err = pthread_cond_init (&lock->waiting_writers, NULL); + if (err != 0) + return err; + lock->waiting_writers_count = 0; + lock->runcount = 0; + return 0; +} + +int +glthread_rwlock_rdlock_multithreaded (gl_rwlock_t *lock) +{ + int err; + + err = pthread_mutex_lock (&lock->lock); + if (err != 0) + return err; + /* Test whether only readers are currently running, and whether the runcount + field will not overflow, and whether no writer is waiting. The latter + condition is because POSIX recommends that "write locks shall take + precedence over read locks", to avoid "writer starvation". */ + while (!(lock->runcount + 1 > 0 && lock->waiting_writers_count == 0)) + { + /* This thread has to wait for a while. Enqueue it among the + waiting_readers. */ + err = pthread_cond_wait (&lock->waiting_readers, &lock->lock); + if (err != 0) + { + pthread_mutex_unlock (&lock->lock); + return err; + } + } + lock->runcount++; + return pthread_mutex_unlock (&lock->lock); +} + +int +glthread_rwlock_wrlock_multithreaded (gl_rwlock_t *lock) +{ + int err; + + err = pthread_mutex_lock (&lock->lock); + if (err != 0) + return err; + /* Test whether no readers or writers are currently running. */ + while (!(lock->runcount == 0)) + { + /* This thread has to wait for a while. Enqueue it among the + waiting_writers. */ + lock->waiting_writers_count++; + err = pthread_cond_wait (&lock->waiting_writers, &lock->lock); + if (err != 0) + { + lock->waiting_writers_count--; + pthread_mutex_unlock (&lock->lock); + return err; + } + lock->waiting_writers_count--; + } + lock->runcount--; /* runcount becomes -1 */ + return pthread_mutex_unlock (&lock->lock); +} + +int +glthread_rwlock_unlock_multithreaded (gl_rwlock_t *lock) +{ + int err; + + err = pthread_mutex_lock (&lock->lock); + if (err != 0) + return err; + if (lock->runcount < 0) + { + /* Drop a writer lock. */ + if (!(lock->runcount == -1)) + { + pthread_mutex_unlock (&lock->lock); + return EINVAL; + } + lock->runcount = 0; + } + else + { + /* Drop a reader lock. */ + if (!(lock->runcount > 0)) + { + pthread_mutex_unlock (&lock->lock); + return EINVAL; + } + lock->runcount--; + } + if (lock->runcount == 0) + { + /* POSIX recommends that "write locks shall take precedence over read + locks", to avoid "writer starvation". */ + if (lock->waiting_writers_count > 0) + { + /* Wake up one of the waiting writers. */ + err = pthread_cond_signal (&lock->waiting_writers); + if (err != 0) + { + pthread_mutex_unlock (&lock->lock); + return err; + } + } + else + { + /* Wake up all waiting readers. */ + err = pthread_cond_broadcast (&lock->waiting_readers); + if (err != 0) + { + pthread_mutex_unlock (&lock->lock); + return err; + } + } + } + return pthread_mutex_unlock (&lock->lock); +} + +int +glthread_rwlock_destroy_multithreaded (gl_rwlock_t *lock) +{ + int err; + + err = pthread_mutex_destroy (&lock->lock); + if (err != 0) + return err; + err = pthread_cond_destroy (&lock->waiting_readers); + if (err != 0) + return err; + err = pthread_cond_destroy (&lock->waiting_writers); + if (err != 0) + return err; + return 0; +} + +# endif + +/* --------------------- gl_recursive_lock_t datatype --------------------- */ + +# if HAVE_PTHREAD_MUTEX_RECURSIVE + +# if defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER || defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP + +int +glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock) +{ + pthread_mutexattr_t attributes; + int err; + + err = pthread_mutexattr_init (&attributes); + if (err != 0) + return err; + err = pthread_mutexattr_settype (&attributes, PTHREAD_MUTEX_RECURSIVE); + if (err != 0) + { + pthread_mutexattr_destroy (&attributes); + return err; + } + err = pthread_mutex_init (lock, &attributes); + if (err != 0) + { + pthread_mutexattr_destroy (&attributes); + return err; + } + err = pthread_mutexattr_destroy (&attributes); + if (err != 0) + return err; + return 0; +} + +# else + +int +glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock) +{ + pthread_mutexattr_t attributes; + int err; + + err = pthread_mutexattr_init (&attributes); + if (err != 0) + return err; + err = pthread_mutexattr_settype (&attributes, PTHREAD_MUTEX_RECURSIVE); + if (err != 0) + { + pthread_mutexattr_destroy (&attributes); + return err; + } + err = pthread_mutex_init (&lock->recmutex, &attributes); + if (err != 0) + { + pthread_mutexattr_destroy (&attributes); + return err; + } + err = pthread_mutexattr_destroy (&attributes); + if (err != 0) + return err; + lock->initialized = 1; + return 0; +} + +int +glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock) +{ + if (!lock->initialized) + { + int err; + + err = pthread_mutex_lock (&lock->guard); + if (err != 0) + return err; + if (!lock->initialized) + { + err = glthread_recursive_lock_init_multithreaded (lock); + if (err != 0) + { + pthread_mutex_unlock (&lock->guard); + return err; + } + } + err = pthread_mutex_unlock (&lock->guard); + if (err != 0) + return err; + } + return pthread_mutex_lock (&lock->recmutex); +} + +int +glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock) +{ + if (!lock->initialized) + return EINVAL; + return pthread_mutex_unlock (&lock->recmutex); +} + +int +glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock) +{ + int err; + + if (!lock->initialized) + return EINVAL; + err = pthread_mutex_destroy (&lock->recmutex); + if (err != 0) + return err; + lock->initialized = 0; + return 0; +} + +# endif + +# else + +int +glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock) +{ + int err; + + err = pthread_mutex_init (&lock->mutex, NULL); + if (err != 0) + return err; + lock->owner = (pthread_t) 0; + lock->depth = 0; + return 0; +} + +int +glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock) +{ + pthread_t self = pthread_self (); + if (lock->owner != self) + { + int err; + + err = pthread_mutex_lock (&lock->mutex); + if (err != 0) + return err; + lock->owner = self; + } + if (++(lock->depth) == 0) /* wraparound? */ + { + lock->depth--; + return EAGAIN; + } + return 0; +} + +int +glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock) +{ + if (lock->owner != pthread_self ()) + return EPERM; + if (lock->depth == 0) + return EINVAL; + if (--(lock->depth) == 0) + { + lock->owner = (pthread_t) 0; + return pthread_mutex_unlock (&lock->mutex); + } + else + return 0; +} + +int +glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock) +{ + if (lock->owner != (pthread_t) 0) + return EBUSY; + return pthread_mutex_destroy (&lock->mutex); +} + +# endif + +/* -------------------------- gl_once_t datatype -------------------------- */ + +static const pthread_once_t fresh_once = PTHREAD_ONCE_INIT; + +int +glthread_once_singlethreaded (pthread_once_t *once_control) +{ + /* We don't know whether pthread_once_t is an integer type, a floating-point + type, a pointer type, or a structure type. */ + char *firstbyte = (char *)once_control; + if (*firstbyte == *(const char *)&fresh_once) + { + /* First time use of once_control. Invert the first byte. */ + *firstbyte = ~ *(const char *)&fresh_once; + return 1; + } + else + return 0; +} + +# if !(PTHREAD_IN_USE_DETECTION_HARD || USE_POSIX_THREADS_WEAK) + +int +glthread_once_multithreaded (pthread_once_t *once_control, + void (*init_function) (void)) +{ + int err = pthread_once (once_control, init_function); + if (err == ENOSYS) + { + /* This happens on FreeBSD 11: The pthread_once function in libc returns + ENOSYS. */ + if (glthread_once_singlethreaded (once_control)) + init_function (); + return 0; + } + return err; +} + +# endif + +#endif + +/* ========================================================================= */ + +#if USE_WINDOWS_THREADS + +#endif + +/* ========================================================================= */ |