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QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running QNX Neutrino 7.1.
Utilities & Libraries
C Library Reference
P
pthread_spin_lock()
Lock a thread spinlock

QNX Momentics IDE User's Guide
This User's Guide describes version 7.1 of the Integrated Development Environment (IDE) that's part of the QNX Momentics tool suite.
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running QNX Neutrino 7.1.
- Quickstart Guide
- OS Components & Operations
- Audio & Graphics API
- Multimedia
- Networking Middleware
- Programming
- Sensor Framework
- System Security Guide
  The QNX System Security Guide is intended for both system integrators who are responsible for the security of a QNX Neutrino RTOS system and developers who want to create a QNX Neutrino resource manager free from vulnerabilities.
- Utilities & Libraries
  - Addon Interfaces Library Reference
  - C Library Reference
    - What's in a Function Description?
    - Manifests
    - Character Sets
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      - pathconf()
        Return the value of a configurable limit
      - pathfind(), pathfind_r()
        Search for a file in a list of directories
      - pathmgr_link()
        Create a node in the path space that represents the mountpoint of a device or filesystem
      - pathmgr_symlink()
        Create a symlink
      - pathmgr_unlink()
        Remove a link
      - pause()
        Suspend the calling thread until it runs a signal handler
      - pci_*()
        Connect to the PCI server
      - pclose()
        Close a pipe
      - perror()
        Print an error message associated with errno
      - pipe()
        Create a pipe
      - poll()
        Multiplex input/output over a set of file descriptors
      - popen()
        Execute a command, creating a pipe to it
      - posix_devctl()
        Control a device
      - posix_fadvise(), posix_fadvise64()
        Provide advisory information about the expected use of a file
      - posix_fallocate(), posix_fallocate64()
        Allocate space for a file on the filesystem
      - posix_madvise()
        Provide advisory information about the expected use of memory
      - posix_mem_offset(), posix_mem_offset64()
        Get the physical address and length of a mapped memory block
      - posix_memalign()
        Allocate aligned memory
      - posix_openpt()
        Open a pseudo-terminal device
      - posix_spawn(), posix_spawnp()
        Spawn a process
      - posix_spawn_file_actions_addclose()
        Add a close a file descriptor action to a spawn file actions object
      - posix_spawn_file_actions_adddup2()
        Add a duplicate a file descriptor action to a spawn file actions object
      - posix_spawn_file_actions_addopen()
        Add an open a file action to a spawn file action object
      - posix_spawn_file_actions_destroy()
        Destroy a spawn file actions object
      - posix_spawn_file_actions_init()
        Initialize a spawn file actions object
      - posix_spawnattr_destroy()
        Destroy a spawn attributes object
      - posix_spawnattr_getaslr()
        Return the Address Space Layout Randomization (ASLR) setting from a posix_spawn() attribute structure
      - posix_spawnattr_getcred()
        Get the user and group ID attributes from a spawn attributes object
      - posix_spawnattr_getflags()
        Get the POSIX flags from a spawn attributes object
      - posix_spawnattr_getnode()
        Get the remote node attribute from a spawn attributes object
      - posix_spawnattr_getpgroup()
        Get the process group attribute of a spawn attributes object
      - posix_spawnattr_getrunmask()
        Get the runmask attribute from a spawn attributes object
      - posix_spawnattr_getschedparam()
        Get the scheduling parameters attribute of a spawn attributes object
      - posix_spawnattr_getschedpolicy()
        Get the scheduling policy attribute of a spawn attributes object
      - posix_spawnattr_getsigdefault()
        Get the default signals attribute of a spawn attributes object
      - posix_spawnattr_getsigignore()
        Get the ignored signals attribute from a spawn attributes object
      - posix_spawnattr_getsigmask()
        Get the signal mask attribute of a spawn attributes object
      - posix_spawnattr_getstackmax()
        Get the maximum stack size attribute from a spawn attributes object
      - posix_spawnattr_gettypeid()
        Get the type identifier of a spawn attributes object
      - posix_spawnattr_getxflags()
        Get the POSIX flags and the QNX Neutrino extended flags from a spawn attributes object
      - posix_spawnattr_init()
        Initialize a spawn attributes object
      - posix_spawnattr_setasid()
        Set the address space ID attribute in a spawn attributes object
      - posix_spawnattr_setaslr()
        Control how the Address Space Layout Randomization (ASLR) setting of a child is determined
      - posix_spawnattr_setcred()
        Set the user and group ID attributes in a spawn attributes object
      - posix_spawnattr_setcwd_np()
        Set the current working directory attribute in a spawn attributes object
      - posix_spawnattr_setflags()
        Set the POSIX flags in a spawn attributes object
      - posix_spawnattr_setnode()
        Set the remote node attribute in a spawn attributes object
      - posix_spawnattr_setpgroup()
        Set the process group attribute in a spawn attributes object
      - posix_spawnattr_setrunmask()
        Set the runmask attribute in a spawn attributes object
      - posix_spawnattr_setschedparam()
        Set the scheduling parameters attribute of a spawn attributes object
      - posix_spawnattr_setschedpolicy()
        Set the scheduling policy attribute of a spawn attributes object
      - posix_spawnattr_setsigdefault()
        Set the default signals attribute of a spawn attributes object
      - posix_spawnattr_setsigignore()
        Set the ignored signals attribute of a spawn attributes object
      - posix_spawnattr_setsigmask()
        Set the signal mask attribute of a spawn attributes object
      - posix_spawnattr_setstackmax()
        Set the maximum stack size attribute in a spawn attributes object
      - posix_spawnattr_settypeid()
        Set the type identifier of a spawn attributes object
      - posix_spawnattr_setxflags()
        Set the POSIX flags and the QNX Neutrino extended flags in a spawn attributes object
      - posix_typed_mem_get_info()
        Get information about a typed memory object
      - posix_typed_mem_open()
        Open a typed memory object
      - pow(), powf(), powl()
        Raise a number to a given power
      - PowerGetActive()
        Query the kernel for a CPU's active frequency parameter
      - PowerParameter()
        Get or set a power parameter
      - PowerSetActive()
        Inform the kernel that the system has switched to a new active frequency
      - pread(), pread64()
        Read from a file without moving the file pointer
      - printf()
        Write formatted output to stdout
      - prlimit(), prlimit64()
        Set and get the limit on a system resource
      - procmgr_ability()
        Control a process's ability to perform certain operations
      - procmgr_ability_create()
        Create a process-manager ability
      - procmgr_ability_lookup()
        Look up a process-manager ability
      - procmgr_ability_name()
        Get the name of a custom ability
      - procmgr_daemon()
        Run a process in the background
      - procmgr_event_notify()
        Ask to be notified of system-wide events
      - procmgr_event_notify_add()
        Add a request to be notified of system-wide events
      - procmgr_event_notify_delete()
        Delete a request to be notified of system-wide events
      - procmgr_event_trigger(), procmgr_event_trigger_updateable()
        Trigger a system-wide event
      - procmgr_guardian()
        Let a process take over as a parent
      - procmgr_session(), procmgr_session_ext()
        Provide process manager session support
      - procmgr_set_type_id()
        Allows a function to change its own type identifier
      - procmgr_timer_tolerance()
        Get or set the default timer tolerance for a process
      - procmgr_value_current()
        Get the current value of an item being monitored
      - procmgr_value_notify_add()
        Add an event to be triggered when a monitored value crosses a trigger point
      - __progname
        The basename of the program being executed
      - protoent
        Structure for information from the protocol database
      - pthread_abort()
        Unconditionally terminate the target thread
      - pthread_atfork()
        Register fork handlers
      - pthread_attr_destroy()
        Destroy a thread-attribute object
      - pthread_attr_getdetachstate()
        Get the thread detach state attribute
      - pthread_attr_getguardsize()
        Get the size of the thread's guard area
      - pthread_attr_getinheritsched()
        Get a thread's inherit-scheduling attribute
      - pthread_attr_getschedparam()
        Get the thread scheduling parameters attribute
      - pthread_attr_getschedpolicy()
        Get the thread scheduling policy attribute
      - pthread_attr_getscope()
        Get the thread contention scope attribute
      - pthread_attr_getstack()
        Get the thread-creation stack attributes
      - pthread_attr_getstackaddr()
        Get the thread stack address attribute
      - pthread_attr_getstacklazy()
        Get the thread lazy-stack attribute
      - pthread_attr_getstackprealloc()
        Get the amount of memory to preallocate for a thread's MAP_LAZY stack
      - pthread_attr_getstacksize()
        Get the thread stack-size attribute
      - pthread_attr_getsuspendstate_np()
        Get the thread suspend state attribute
      - pthread_attr_init()
        Initialize a thread-attribute object
      - pthread_attr_setdetachstate()
        Set the thread detach state attribute
      - pthread_attr_setguardsize()
        Set the size of the thread's guard area
      - pthread_attr_setinheritsched()
        Set the thread's inherit-scheduling attribute
      - pthread_attr_setschedparam()
        Set a thread's scheduling parameters attribute
      - pthread_attr_setschedpolicy()
        Set the thread scheduling policy attribute
      - pthread_attr_setscope()
        Set the thread contention scope attribute
      - pthread_attr_setstack()
        Set the thread-creation stack attributes
      - pthread_attr_setstackaddr()
        Set the thread stack address attribute
      - pthread_attr_setstacklazy()
        Set the thread lazy-stack attribute
      - pthread_attr_setstackprealloc()
        Set the amount of memory to preallocate for a thread's MAP_LAZY stack
      - pthread_attr_setstacksize()
        Set the thread stack-size attribute
      - pthread_attr_setsuspendstate_np()
        Set the thread suspend state attribute
      - pthread_barrier_destroy()
        Destroy a barrier object
      - pthread_barrier_init()
        Initialize a barrier object
      - pthread_barrier_wait()
        Synchronize participating threads at the barrier
      - pthread_barrierattr_destroy()
        Destroy a barrier-attributes object
      - pthread_barrierattr_getpshared()
        Get the value of a barrier's process-shared attribute
      - pthread_barrierattr_init()
        Initialize a barrier attributes object
      - pthread_barrierattr_setpshared()
        Set the value of a barrier's process-shared attribute
      - pthread_cancel()
        Cancel a thread
      - pthread_cleanup_pop()
        Pop a function off of a thread's cancellation-cleanup stack
      - pthread_cleanup_push()
        Push a function onto a thread's cancellation-cleanup stack
      - pthread_cond_broadcast()
        Unblock threads waiting on a condition
      - pthread_cond_clockwait()
        Wait on a condition variable, with a time limit measured against a specific clock
      - pthread_cond_destroy()
        Destroy a condition variable
      - pthread_cond_init()
        Initialize a condition variable
      - pthread_cond_signal()
        Unblock a thread that's waiting on a condition variable
      - pthread_cond_timedwait()
        Wait on a condition variable, with a time limit
      - pthread_cond_wait()
        Wait on a condition variable
      - pthread_condattr_destroy()
        Destroy a condition-variable attribute object
      - pthread_condattr_getclock()
        Get the clock attribute from a condition-variable attribute object
      - pthread_condattr_getpshared()
        Get the process-shared attribute from a condition variable attribute object
      - pthread_condattr_init()
        Initialize the attribute object for creating condition variables
      - pthread_condattr_setclock()
        Set the clock attribute of a condition-variable attribute object
      - pthread_condattr_setpshared()
        Set the process-shared attribute in a condition variable attribute object
      - pthread_create()
        Create a thread
      - pthread_detach()
        Detach a thread from a process
      - pthread_equal()
        Compare two thread IDs
      - pthread_exit()
        Terminate a thread
      - pthread_getconcurrency()
        Get the level of thread concurrency
      - pthread_getcpuclockid()
        Return the clock ID of the CPU-time clock from a specified thread
      - pthread_getname_np()
        Retrieve the name of a thread
      - pthread_getschedparam()
        Get a thread's scheduling parameters
      - pthread_getspecific()
        Get a thread-specific data value
      - pthread_join()
        Join thread
      - pthread_key_create()
        Create a thread-specific data key
      - pthread_key_delete()
        Delete a thread-specific data key
      - pthread_kill()
        Send a signal to a thread
      - pthread_mutex_clocklock()
        Lock a mutex with a time limit measured against a specific clock
      - pthread_mutex_consistent()
        Mark as consistent the state that's protected by a mutex
      - pthread_mutex_destroy()
        Destroy a mutex
      - pthread_mutex_getprioceiling()
        Get a mutex's priority ceiling
      - pthread_mutex_init()
        Initialize a mutex
      - pthread_mutex_lock()
        Lock a mutex
      - pthread_mutex_setprioceiling()
        Set a mutex's priority ceiling
      - pthread_mutex_timedlock(), pthread_mutex_timedlock_monotonic()
        Lock a mutex, with a time limit
      - pthread_mutex_trylock()
        Attempt to lock a mutex
      - pthread_mutex_unlock()
        Unlock a mutex
      - pthread_mutex_wakeup_np()
        Unblock any threads that are waiting on a mutex
      - pthread_mutexattr_destroy()
        Destroy mutex attribute object
      - pthread_mutexattr_getprioceiling()
        Get the priority ceiling of a mutex attribute object
      - pthread_mutexattr_getprotocol()
        Get a mutex's scheduling protocol
      - pthread_mutexattr_getpshared()
        Get the process-shared attribute from a mutex attribute object
      - pthread_mutexattr_getrecursive()
        Get the recursive attribute from a mutex attribute object
      - pthread_mutexattr_getrobust()
        Get the robust attribute from a mutex attribute object
      - pthread_mutexattr_gettype()
        Get a mutex type
      - pthread_mutexattr_getwakeup_np()
        Get the wake-up attribute of a mutex
      - pthread_mutexattr_init()
        Initialize a mutex attribute object
      - pthread_mutexattr_setprioceiling()
        Set the priority ceiling of a mutex attribute object
      - pthread_mutexattr_setprotocol()
        Set a mutex's scheduling protocol
      - pthread_mutexattr_setpshared()
        Set the process-shared attribute in mutex attribute object
      - pthread_mutexattr_setrecursive()
        Set the recursive attribute in mutex attribute object
      - pthread_mutexattr_setrobust()
        Set the robust attribute in a mutex attribute object
      - pthread_mutexattr_settype()
        Set a mutex type
      - pthread_mutexattr_setwakeup_np()
        Set the wake-up attribute of a mutex
      - pthread_once()
        Dynamic package initialization
      - pthread_rwlock_clockrdlock()
        Lock a read-write lock for reading with a time limit measured against a clock
      - pthread_rwlock_clockwrlock()
        Lock a read-write lock for writing with a time limit measured against a specific clock
      - pthread_rwlock_destroy()
        Destroy a read-write lock
      - pthread_rwlock_init()
        Initialize a read-write lock
      - pthread_rwlock_rdlock()
        Acquire a shared read lock on a read-write lock
      - pthread_rwlock_timedrdlock()
        Lock a read-write lock for reading
      - pthread_rwlock_timedwrlock()
        Lock a read-write lock for writing
      - pthread_rwlock_tryrdlock()
        Attempt to acquire a shared lock on a read-write lock
      - pthread_rwlock_trywrlock()
        Attempt to acquire an exclusive lock on a read-write lock
      - pthread_rwlock_unlock()
        Unlock a read-write lock
      - pthread_rwlock_wrlock()
        Acquire an exclusive write lock on a read-write lock
      - pthread_rwlockattr_destroy()
        Destroy a read-write lock attribute object
      - pthread_rwlockattr_getclock()
        Get the clock attribute from a read-write lock attribute object
      - pthread_rwlockattr_getpshared()
        Get the process-shared attribute of a read-write lock attribute object
      - pthread_rwlockattr_init()
        Create a read-write lock attribute object
      - pthread_rwlockattr_setclock()
        Set the clock attribute of a read-write lock attribute object
      - pthread_rwlockattr_setpshared()
        Set the process-shared attribute of a read-write lock attribute object
      - pthread_self()
        Get the calling thread's ID
      - pthread_setcancelstate()
        Set a thread's cancellation state
      - pthread_setcanceltype()
        Set a thread's cancellation type
      - pthread_setconcurrency()
        Set the concurrency level for a thread
      - pthread_setname_np()
        Name a thread
      - pthread_setschedparam()
        Set thread scheduling parameters
      - pthread_setschedprio()
        Set a thread's priority
      - pthread_setspecific()
        Set a thread-specific data value
      - pthread_sigmask()
        Modify or examine a thread's signal-blocked mask
      - pthread_sleepon_broadcast()
        Unblock waiting threads
      - pthread_sleepon_lock()
        Lock the pthread_sleepon* functions
      - pthread_sleepon_signal()
        Signal a sleeping thread
      - pthread_sleepon_timedwait()
        Make a thread sleep while waiting
      - pthread_sleepon_unlock()
        Unlock the pthread_sleepon*() functions
      - pthread_sleepon_wait()
        Make a thread sleep while waiting
      - pthread_spin_destroy()
        Destroy a thread spinlock
      - pthread_spin_init()
        Initialize a thread spinlock
      - pthread_spin_lock()
        Lock a thread spinlock
      - pthread_spin_trylock()
        Try to lock a thread spinlock
      - pthread_spin_unlock()
        Unlock a thread spinlock
      - pthread_testcancel()
        Test thread cancellation
      - pthread_timedjoin(), pthread_timedjoin_monotonic()
        Join a thread, with a time limit
      - ptsname()
        Get the name of a slave pseudo-terminal device
      - ptsname_r()
        Get the name of a slave pseudo-terminal device
      - _pulse
        Structure that describes a pulse
      - pulse_attach()
        Attach a handler function to a pulse code
      - pulse_detach()
        Detach a handler function from a pulse code
      - putc()
        Write a character to a stream
      - putc_unlocked()
        Write a character to an output stream
      - putchar()
        Write a character to standard output
      - putchar_unlocked()
        Write a character to stdout
      - putenv()
        Add, change or delete an environment variable
      - puts()
        Write a string to stdout
      - putspent()
        Put an entry into the shadow password database
      - pututline()
        Write an entry in the user-information file
      - putw()
        Put a word on a stream
      - putwc()
        Write a wide character to a stream
      - putwchar()
        Write a wide character to a stdout
      - pwrite(), pwrite64()
        Write into a file without changing the file pointer
    - Q
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    - V
    - W
    - X
    - Y
    - Z
    - Full Safety Information
    - Glossary
  - Devctl and Ioctl Commands
  - JSON Library Reference
  - PAM Reference
  - Utilities Reference
  - WPA Control Interface Reference
    This document provides a reference for the Wi-Fi Protected Access (WPA) control interface, which provides a C API for the WPA/IEEE 802.11i protocols in Wi-Fi client stations. Application developers who want to control WPA operations and get associated status and event data should read this reference.
QNX Hypervisor
The QNX Hypervisor allows you to run multiple OSs on a target system so you can separate critical and non-critical functions, support a wide variety of applications, and reduce hardware costs.
QNX Software in the Cloud
QNX Software in the Cloud enables developers to use the QNX software in Amazon Web Services (AWS) and Microsoft Azure (Azure).
QNX Advanced Virtualization Frameworks User's Guide
This User's Guide is aimed at all systems integrators and developers who want to design and build embedded systems using the QNX Advanced Virtualization Frameworks.
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation and explains how to obtain technical support.

pthread_spin_lock()

Lock a thread spinlock

Synopsis:

#include <pthread.h>

int pthread_spin_lock( pthread_spinlock_t * spinner );

Arguments:

spinner: A pointer to the pthread_spinlock_t object that you want to lock.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The pthread_spin_lock() function locks the thread spinlock specified by spinner. If spinner isn't immediately available, pthread_spin_lock() blocks until spinner can be locked.

If a thread attempts to lock a spinlock that's already locked via pthread_spin_lock() or pthread_spin_trylock(), the thread returns EDEADLK.

Returns:

EOK: Success.
EDEADLK: The calling thread already holds the lock in spinner.
EINVAL: The spinner object is invalid.

Classification:


Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	Yes
Thread	Yes

Caveats:

You may not get the desired behavior from this function because the current implementation is through mutexes. In the uncontested case, this gives the same behavior as spinlocks. In the contested case, this function makes a kernel call and may block.

Page updated: March 12, 2026