---
name: "pthread_mutex_unlock"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd", "macos"]
url: "https://new.carta.tech/pthread_mutex_unlock"
---

# pthread\_mutex\_unlock(3)

unlock a mutex

## NAME

**pthread\_mutex\_unlock** – unlock a mutex

## LIBRARY

POSIX Threads Library (libpthread, -lpthread)

## SYNOPSIS

**#include \<pthread.h\>**

*int*\

**pthread\_mutex\_unlock**(*pthread\_mutex\_t \*mutex*);

## DESCRIPTION

If the current thread holds the lock on *mutex*, then the **pthread\_mutex\_unlock**() function unlocks *mutex*.

If the argument pointed by the *mutex* is a robust mutex in the inconsistent state, and the call to **pthread\_mutex\_consistent**() function was not done prior to unlocking, further locking attempts on the mutex *mutex* are denied and locking functions return ENOTRECOVERABLE error.

## RETURN VALUES

If successful, **pthread\_mutex\_unlock**() will return zero, otherwise an error number will be returned to indicate the error.

## ERRORS

The **pthread\_mutex\_unlock**() function will fail if:

- \[EINVAL\]

  The value specified by *mutex* is invalid.

- \[EPERM\]

  The current thread does not hold a lock on *mutex*.

## SEE ALSO

[pthread\_mutex\_destroy(3)](/pthread_mutex_destroy/3.md), [pthread\_mutex\_init(3)](/pthread_mutex_init/3.md), [pthread\_mutex\_lock(3)](/pthread_mutex_lock/3.md), [pthread\_mutex\_trylock(3)](/pthread_mutex_trylock/3.md)

## STANDARDS

The **pthread\_mutex\_unlock**() function conforms to ISO/IEC 9945-1:1996 (“POSIX.1”).