man3/pthread_spin_lock.3

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  25 .TH PTHREAD_SPIN_LOCK 3 2017-09-30 "Linux" "Linux Programmer's Manual"
  26 .SH NAME
  27 pthread_spin_lock, pthread_spin_trylock, pthread_spin_unlock \-
  28 lock and unlock a spin lock
  29 .SH SYNOPSIS
  30 .nf
  31 .B #include <pthread.h>
  32 .PP
  33 .BI "int pthread_spin_lock(pthread_spinlock_t *" lock );
  34 .BI "int pthread_spin_trylock(pthread_spinlock_t *" lock );
  35 .BI "int pthread_spin_unlock(pthread_spinlock_t *" lock );
  36 .fi
  37 .PP
  38 Compile and link with \fI\-pthread\fP.
  39 .PP
  40 .in -4n
  41 Feature Test Macro Requirements for glibc (see
  42 .BR feature_test_macros (7)):
  43 .in
  44 .PP
  45 .BR pthread_spin_lock (),
  46 .BR pthread_spin_trylock ():
  47 .br
  48 .RS 4
  49 .ad l
  50 _POSIX_C_SOURCE >= 200112L
  51 .RE
  52 .ad
  53 .SH DESCRIPTION
  54 The
  55 .BR pthread_spin_lock ()
  56 function locks the spin lock referred to by
  57 .IR lock .
  58 If the spin lock is currently unlocked,
  59 the calling thread acquires the lock immediately.
  60 If the spin lock is currently locked by another thread,
  61 the calling thread spins, testing the lock until it becomes available,
  62 at which point the calling thread acquires the lock.
  63 .PP
  64 Calling
  65 .BR pthread_spin_lock ()
  66 on a lock that is already held by the caller results in undefined behavior.
  67 .PP
  68 The
  69 .BR pthread_spin_trylock ()
  70 function is like
  71 .BR pthread_spin_lock (),
  72 except that if the spin lock referred to by
  73 .I lock
  74 is currently locked,
  75 then, instead of spinning, the call returns immediately with the error
  76 .BR EBUSY .
  77 .PP
  78 The
  79 .BR pthread_spin_unlock ()
  80 function unlocks the spin lock referred to
  81 .IR lock .
  82 If any threads are spinning on the lock,
  83 one of those threads will then acquire the lock.
  84 .PP
  85 Calling
  86 .BR pthread_spin_unlock ()
  87 on a lock that is not held by the caller results in undefined behavior.
  88 .SH RETURN VALUE
  89 On success, there functions return zero.
  90 On failure, they return an error number.
  91 .SH ERRORS
  92 .BR pthread_spin_lock ()
  93 may fail with the following errors:
  94 .TP
  95 .B EDEADLOCK
  96 .\" Not detected in glibc
  97 The system detected a deadlock condition.
  98 .PP
  99 .BR pthread_spin_trylock ()
 100 can fail with the following errors:
 101 .TP
 102 .B EBUSY
 103 The spin lock is currently locked by another thread.
 104 .SH VERSIONS
 105 These functions first appeared in glibc in version 2.2.
 106 .SH CONFORMING TO
 107 POSIX.1-2001.
 108 .SH NOTES
 109 Applying any of the functions described on this page to
 110 an uninitialized spin lock results in undefined behavior.
 111 .SH SEE ALSO
 112 .ad l
 113 .nh
 114 .\" FIXME . .BR pthread_mutex_lock (3),
 115 .BR pthread_spin_destroy (3),
 116 .BR pthread_spin_init (3),
 117 .BR pthreads (7)