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
  67 or a lock that has not been initialized with
  68 .BR pthread_spin_init (3)
  69 results in undefined behavior.
  70 .PP
  71 The
  72 .BR pthread_spin_trylock ()
  73 function is like
  74 .BR pthread_spin_lock (),
  75 except that if the spin lock referred to by
  76 .I lock
  77 is currently locked,
  78 then, instead of spinning, the call returns immediately with the error
  79 .BR EBUSY .
  80 .PP
  81 The
  82 .BR pthread_spin_unlock ()
  83 function unlocks the spin lock referred to
  84 .IR lock .
  85 If any threads are spinning on the lock,
  86 one of those threads will then acquire the lock.
  87 .PP
  88 Calling
  89 .BR pthread_spin_unlock ()
  90 on a lock that is not held by the caller results in undefined behavior.
  91 .SH RETURN VALUE
  92 On success, these functions return zero.
  93 On failure, they return an error number.
  94 .SH ERRORS
  95 .BR pthread_spin_lock ()
  96 may fail with the following errors:
  97 .TP
  98 .B EDEADLOCK
  99 .\" Not detected in glibc
 100 The system detected a deadlock condition.
 101 .PP
 102 .BR pthread_spin_trylock ()
 103 fails with the following errors:
 104 .TP
 105 .B EBUSY
 106 The spin lock is currently locked by another thread.
 107 .SH VERSIONS
 108 These functions first appeared in glibc in version 2.2.
 109 .SH CONFORMING TO
 110 POSIX.1-2001.
 111 .SH NOTES
 112 Applying any of the functions described on this page to
 113 an uninitialized spin lock results in undefined behavior.
 114 .PP
 115 Carefully read NOTES in
 116 .BR pthread_spin_init (3).
 117 .SH SEE ALSO
 118 .ad l
 119 .nh
 120 .\" FIXME . .BR pthread_mutex_lock (3),
 121 .BR pthread_spin_destroy (3),
 122 .BR pthread_spin_init (3),
 123 .BR pthreads (7)