Zephyr API Documentation  3.7.0-rc3
A Scalable Open Source RTOS
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FUTEX APIs

Functions

int k_futex_wait (struct k_futex *futex, int expected, k_timeout_t timeout)
 Pend the current thread on a futex.
 
int k_futex_wake (struct k_futex *futex, bool wake_all)
 Wake one/all threads pending on a futex.
 

Detailed Description

Function Documentation

◆ k_futex_wait()

int k_futex_wait ( struct k_futex futex,
int  expected,
k_timeout_t  timeout 
)

#include <zephyr/kernel.h>

Pend the current thread on a futex.

Tests that the supplied futex contains the expected value, and if so, goes to sleep until some other thread calls k_futex_wake() on it.

Parameters
futexAddress of the futex.
expectedExpected value of the futex, if it is different the caller will not wait on it.
timeoutWaiting period on the futex, or one of the special values K_NO_WAIT or K_FOREVER.
Return values
-EACCESCaller does not have read access to futex address.
-EAGAINIf the futex value did not match the expected parameter.
-EINVALFutex parameter address not recognized by the kernel.
-ETIMEDOUTThread woke up due to timeout and not a futex wakeup.
0if the caller went to sleep and was woken up. The caller should check the futex's value on wakeup to determine if it needs to block again.

◆ k_futex_wake()

int k_futex_wake ( struct k_futex futex,
bool  wake_all 
)

#include <zephyr/kernel.h>

Wake one/all threads pending on a futex.

Wake up the highest priority thread pending on the supplied futex, or wakeup all the threads pending on the supplied futex, and the behavior depends on wake_all.

Parameters
futexFutex to wake up pending threads.
wake_allIf true, wake up all pending threads; If false, wakeup the highest priority thread.
Return values
-EACCESCaller does not have access to the futex address.
-EINVALFutex parameter address not recognized by the kernel.
Numberof threads that were woken up.