.\" Copyright (c) 2004 Michael Telahun Makonnen
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.\" $FreeBSD: head/share/man/man3/pthread_spin_lock.3 172880 2007-10-22 10:08:01Z ru $
.\"
.Dd January 22, 2004
.Dt PTHREAD_SPIN_LOCK 3
.Os
.Sh NAME
.Nm pthread_spin_lock , pthread_spin_trylock , pthread_spin_unlock
.Nd "lock or unlock a spin lock"
.Sh LIBRARY
.Lb libpthread
.Sh SYNOPSIS
.In pthread.h
.Ft int
.Fn pthread_spin_lock "pthread_spinlock_t *lock"
.Ft int
.Fn pthread_spin_trylock "pthread_spinlock_t *lock"
.Ft int
.Fn pthread_spin_unlock "pthread_spinlock_t *lock"
.Sh DESCRIPTION
The
.Fn pthread_spin_lock
function will acquire
.Fa lock
if it is not currently owned by another thread.
If the lock cannot be acquired immediately, it will
spin attempting to acquire the lock (it will not sleep) until
it becomes available.
.Pp
The
.Fn pthread_spin_trylock
function is the same as
.Fn pthread_spin_lock
except that if it cannot acquire
.Fa lock
immediately it will return with an error.
.Pp
The
.Fn pthread_spin_unlock
function will release
.Fa lock ,
which must have been previously locked by a call to
.Fn pthread_spin_lock
or
.Fn pthread_spin_trylock .
.Sh RETURN VALUES
If successful, all these functions will return zero.
Otherwise, an error number will be returned to indicate the error.
.Pp
None of these functions will return
.Er EINTR .
.Sh ERRORS
The
.Fn pthread_spin_lock ,
.Fn pthread_spin_trylock
and
.Fn pthread_spin_unlock
functions will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The value specified by
.Fa lock
is invalid or is not initialized.
.El
.Pp
The
.Fn pthread_spin_lock
function may fail if:
.Bl -tag -width Er
.It Bq Er EDEADLK
The calling thread already owns the lock.
.El
.Pp
The
.Fn pthread_spin_trylock
function will fail if:
.Bl -tag -width Er
.It Bq Er EBUSY
Another thread currently holds
.Fa lock .
.El
.Pp
The
.Fn pthread_spin_unlock
function may fail if:
.Bl -tag -width Er
.It Bq Er EPERM
The calling thread does not own
.Fa lock .
.El
.Sh SEE ALSO
.Xr pthread_spin_destroy 3 ,
.Xr pthread_spin_init 3
.Sh HISTORY
The
.Fn pthread_spin_lock ,
.Fn pthread_spin_trylock
and
.Fn pthread_spin_unlock
functions first appeared in
.Lb libkse
in
.Fx 5.2 ,
and in
.Lb libthr
in
.Fx 5.3 .
.Sh BUGS
The implementation of
.Fn pthread_spin_lock ,
.Fn pthread_spin_trylock
and
.Fn pthread_spin_unlock
is expected to conform to
.St -p1003.2 .