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| .TH PTHREAD_SPIN_LOCK 3 2021-03-22 "Linux" "Linux Programmer's Manual" |
| .SH NAME |
| pthread_spin_lock, pthread_spin_trylock, pthread_spin_unlock \- |
| lock and unlock a spin lock |
| .SH SYNOPSIS |
| .nf |
| .B #include <pthread.h> |
| .PP |
| .BI "int pthread_spin_lock(pthread_spinlock_t *" lock ); |
| .BI "int pthread_spin_trylock(pthread_spinlock_t *" lock ); |
| .BI "int pthread_spin_unlock(pthread_spinlock_t *" lock ); |
| .fi |
| .PP |
| Compile and link with \fI\-pthread\fP. |
| .PP |
| .RS -4 |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .RE |
| .PP |
| .BR pthread_spin_lock (), |
| .BR pthread_spin_trylock (): |
| .nf |
| _POSIX_C_SOURCE >= 200112L |
| .fi |
| .SH DESCRIPTION |
| The |
| .BR pthread_spin_lock () |
| function locks the spin lock referred to by |
| .IR lock . |
| If the spin lock is currently unlocked, |
| the calling thread acquires the lock immediately. |
| If the spin lock is currently locked by another thread, |
| the calling thread spins, testing the lock until it becomes available, |
| at which point the calling thread acquires the lock. |
| .PP |
| Calling |
| .BR pthread_spin_lock () |
| on a lock that is already held by the caller |
| or a lock that has not been initialized with |
| .BR pthread_spin_init (3) |
| results in undefined behavior. |
| .PP |
| The |
| .BR pthread_spin_trylock () |
| function is like |
| .BR pthread_spin_lock (), |
| except that if the spin lock referred to by |
| .I lock |
| is currently locked, |
| then, instead of spinning, the call returns immediately with the error |
| .BR EBUSY . |
| .PP |
| The |
| .BR pthread_spin_unlock () |
| function unlocks the spin lock referred to |
| .IR lock . |
| If any threads are spinning on the lock, |
| one of those threads will then acquire the lock. |
| .PP |
| Calling |
| .BR pthread_spin_unlock () |
| on a lock that is not held by the caller results in undefined behavior. |
| .SH RETURN VALUE |
| On success, these functions return zero. |
| On failure, they return an error number. |
| .SH ERRORS |
| .BR pthread_spin_lock () |
| may fail with the following errors: |
| .TP |
| .B EDEADLOCK |
| .\" Not detected in glibc |
| The system detected a deadlock condition. |
| .PP |
| .BR pthread_spin_trylock () |
| fails with the following errors: |
| .TP |
| .B EBUSY |
| The spin lock is currently locked by another thread. |
| .SH VERSIONS |
| These functions first appeared in glibc in version 2.2. |
| .SH CONFORMING TO |
| POSIX.1-2001. |
| .SH NOTES |
| Applying any of the functions described on this page to |
| an uninitialized spin lock results in undefined behavior. |
| .PP |
| Carefully read NOTES in |
| .BR pthread_spin_init (3). |
| .SH SEE ALSO |
| .ad l |
| .nh |
| .\" FIXME . .BR pthread_mutex_lock (3), |
| .BR pthread_spin_destroy (3), |
| .BR pthread_spin_init (3), |
| .BR pthreads (7) |