#include <pthread.h> int pthread_spin_destroy(pthread_spinlock_t *lock); int pthread_spin_init(pthread_spinlock_t *lock, int pshared);
The pthread_spin_init() function shall allocate any resources required to use the spin lock referenced by lock and initialize the lock to an unlocked state.
If the Thread Process-Shared Synchronization option is supported and the value of pshared is PTHREAD_PROCESS_SHARED, the implementation shall permit the spin lock to be operated upon by any thread that has access to the memory where the spin lock is allocated, even if it is allocated in memory that is shared by multiple processes.
If the Thread Process-Shared Synchronization option is supported and the value of pshared is PTHREAD_PROCESS_PRIVATE, or if the option is not supported, the spin lock shall only be operated upon by threads created within the same process as the thread that initialized the spin lock. If threads of differing processes attempt to operate on such a spin lock, the behavior is undefined.
The results are undefined if pthread_spin_init() is called specifying an already initialized spin lock. The results are undefined if a spin lock is used without first being initialized.
If the pthread_spin_init() function fails, the lock is not initialized and the contents of lock are undefined.
Only the object referenced by lock may be used for performing synchronization.
The result of referring to copies of that object in calls to pthread_spin_destroy(), pthread_spin_lock(), pthread_spin_trylock(), or pthread_spin_unlock() is undefined.
These functions shall not return an error code of [EINTR].
The following sections are informative.
If an implementation detects that the value specified by the lock argument to pthread_spin_destroy() or pthread_spin_init() refers to a locked spin lock object, or detects that the value specified by the lock argument to pthread_spin_init() refers to an already initialized spin lock object, it is recommended that the function should fail and report an [EBUSY] error.
The Base Definitions volume of POSIX.1-2008, <pthread.h>
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