Unix/Linux Go Back    


NetBSD 6.1.5 - man page for pthread_spin (netbsd section 3)

Linux & Unix Commands - Search Man Pages
Man Page or Keyword Search:   man
Select Man Page Set:       apropos Keyword Search (sections above)


PTHREAD_SPIN(3) 		   BSD Library Functions Manual 		  PTHREAD_SPIN(3)

NAME
     pthread_spin -- spin lock interface

LIBRARY
     POSIX Threads Library (libpthread, -lpthread)

SYNOPSIS
     #include <pthread.h>

     int
     pthread_spin_init(pthread_spinlock_t *lock, int pshared);

     int
     pthread_spin_destroy(pthread_spinlock_t *lock);

     int
     pthread_spin_lock(pthread_spinlock_t *lock);

     int
     pthread_spin_trylock(pthread_spinlock_t *lock);

     int
     pthread_spin_unlock(pthread_spinlock_t *lock);

DESCRIPTION
     The pthread_spin_init() function is used to initialize a spin lock.  In the NetBSD implemen-
     tation the pshared parameter is currently unused and all spin locks exhibit the
     PTHREAD_PROCESS_SHARED property, implying that all spin locks may be accessed by threads of
     multiple processes.  The results of calling pthread_spin_init() with an already initialized
     lock are undefined.

     The pthread_spin_destroy() function is used to destroy a spin lock previously created with
     pthread_spin_init().  It is undefined what happens if the function is called when a thread
     holds the lock, or if the function is called with an uninitialized spin lock.

     The pthread_spin_lock() function acquires a spin lock on lock, provided that lock is not
     presently held.  If the lock cannot be immediately acquired, the calling thread repeatedly
     retries until it can acquire the lock.  Undefined behavior may follow if the calling thread
     holds the lock at the time the call is made.

     The pthread_spin_trylock() function performs the same locking action, but does not block if
     the lock cannot be immediately obtained; if the lock is held, the call fails.

     The pthread_spin_unlock() function is used to release the read/write lock previously
     obtained by pthread_spin_lock() or pthread_spin_trylock().  The results are undefined if the
     lock is not held by the calling thread.

RETURN VALUES
     If successful, all described functions return zero.  Otherwise an error number will be
     returned to indicate the error.

ERRORS
     The pthread_spin_init() function shall fail if:

     [ENOMEM]		Insufficient memory exists to initialize the lock.

     The pthread_spin_init() function may fail if:

     [EINVAL]		The lock parameter was NULL or the pshared parameter was neither
			PTHREAD_PROCESS_SHARED nor PTHREAD_PROCESS_PRIVATE.

     The pthread_spin_destroy() function may fail if:

     [EBUSY]		The system has detected an attempt to destroy the object referenced by
			lock while it is locked.

     [EINVAL]		The value specified by lock is invalid.

     The pthread_spin_trylock() function shall fail if:

     [EBUSY]		The lock could not be acquired because a writer holds the lock or was
			blocked on it.

     The pthread_spin_lock() function may fail if:

     [EDEADLK]		The current thread already owns lock for writing.

     The pthread_spin_lock() and pthread_spin_trylock() functions may fail if:

     [EINVAL]		The value specified by lock is invalid.

     The pthread_spin_unlock() function may fail if:

     [EINVAL]		The value specified by lock is invalid.

SEE ALSO
     pthread(3), pthread_barrier(3), pthread_cond(3), pthread_mutex(3), pthread_rwlock(3)

STANDARDS
     These functions conform to IEEE Std 1003.1-2001 (``POSIX.1'').

CAVEATS
     Applications using spin locks are vulnerable to the effects of priority inversion.  Applica-
     tions using real-time threads (SCHED_FIFO), (SCHED_RR) should not use these interfaces.
     Outside carefully controlled environments, priority inversion with spin locks can lead to
     system deadlock.  Mutexes are preferable in nearly every possible use case.

BSD					   July 8, 2010 				      BSD
Unix & Linux Commands & Man Pages : ©2000 - 2018 Unix and Linux Forums


All times are GMT -4. The time now is 07:50 PM.