pthread_mutexattr_setprotocol()

Set a mutex's scheduling protocol

Synopsis:

#include <pthread.h>

int pthread_mutexattr_setprotocol( 
            pthread_mutexattr * attr,
            int protocol );

Arguments:

attr

A pointer to the pthread_mutexattr_t object that you want to set the attribute in.

protocol

The new value of the scheduling protocol; one of:

• PTHREAD_PRIO_INHERIT — when a thread is blocking higher-priority threads by locking one or more mutexes with this attribute, raise the thread's priority to that of the highest priority thread waiting on the PTHREAD_PRIO_INHERIT mutex.
• PTHREAD_PRIO_PROTECT — execute the thread at the highest priority or priority ceilings of all the mutexes owned by the thread and initialized with PTHREAD_PRIO_PROTECT, whether other threads are blocked or not.
• PTHREAD_PRIO_NONE — owning the mutex doesn't affect the priority and scheduling of the thread.

Library:

libc

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

Description:

The pthread_mutexattr_setprotocol() function sets the mutex attribute attr's scheduling protocol to protocol. The structure pointed to by attr must have been previously created with pthread_mutexattr_init().

The protocol attribute defines the protocol for using mutexes. A thread holding a PTHREAD_PRIO_INHERIT mutex won't be moved to the tail of the scheduling queue if its original priority is changed (by a call to pthread_schedsetparam(), for example). This remains true if the thread unlocks the PTHREAD_PRIO_INHERIT mutex.

Returns:

EOK

Success.

ENOTSUP

The protocol argument is an unsupported or an invalid value.

Classification:

POSIX 1003.1 THR TPP|TPI

See also:

pthread_mutexattr_getprotocol(), pthread_mutexattr_getrecursive()

“Mutexes: mutual exclusion locks” in the QNX Neutrino Microkernel chapter of the System Architecture guide