###### (This is the legacy documentation for stable SDL2, the current stable version; [SDL3](https://wiki.libsdl.org/SDL3/) is the current development version.)
# SDL_UnlockMutex

Unlock the mutex.

## Header File

Defined in [SDL_mutex.h](https://github.com/libsdl-org/SDL/blob/SDL2/include/SDL_mutex.h), but apps should _only_ `#include "SDL.h"`!

## Syntax

```c
int SDL_UnlockMutex(SDL_mutex * mutex) SDL_RELEASE(mutex);

```

## Function Parameters

|               |                      |
| ------------- | -------------------- |
| **mutex**     | the mutex to unlock. |

## Return Value

Returns 0, or -1 on error.

## Remarks

It is legal for the owning thread to lock an already-locked mutex. It must
unlock it the same number of times before it is actually made available for
other threads in the system (this is known as a "recursive mutex").

It is an error to unlock a mutex that has not been locked by the current
thread, and doing so results in undefined behavior.

It is also an error to unlock a mutex that isn't locked at all.

## Version

This function is available since SDL 2.0.0.

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[CategoryAPI](CategoryAPI), [CategoryAPIFunction](CategoryAPIFunction)