OSUninterruptibleSpinLock_Acquire

Syntax

#include <cafe/os.h>

BOOL OSUninterruptibleSpinLock_Acquire(OSSpinLock* inSpinlock);

Parameters

inSpinlock Pointer to uninterruptible spinlock.

Return Values

BOOL indicating success or failure.

Description

WARNING:
Threads MUST NOT mix regular OSSpinLocks with OSUninterruptibleSpinLocks.

OSUninterruptibleSpinLock_Acquire busy-waits to acquire an OSUninterruptibleSpinLock if the spinlock has never been acquired. A thread may acquire an OSUninterruptibleSpinLock recursively. Upon acquiring an OSUninterruptibleSpinLock, interrupts are disabled. A thread must not leave interrupts disabled for long periods of time, typically no longer than 1-2 microseconds to avoid disrupting user-mode COS components.

An OSUninterruptibleSpinLock is approximately 5X faster to acquire and release than a regular OSSpinLock and creates no contention for internal COS locks. The major condition is that between acquiring and releasing the OSUninterruptibleSpinLock, interrupts are disabled and must remain disabled until the corresponding OSUninterruptibleSpinLock_Release is called.

OSUninterruptibleSpinLock_Acquire and OSUninterruptibleSpinLock_Release purposely have the same parameter lists and same-sized data structures as the OSSpinLock Acquire and Release functions. This is so that OSUninterruptibleSpinLock can serve as a drop-in replacement for regular OSSpinLock in many situations.

OSUninterruptibleSpinLocks do not participate in the thread canceling mechanism. If a thread wishes to benefit from both the faster OSUninterruptibleSpinLock and from the ability to cross-thread cancel a thread, OSTestThreadCancel should be called before OSUninterruptibleSpinLock_Acquire and after OSUninterruptibleSpinLock_Release.

Important usage notes while holding a spinlock:

OSUninterruptibleSpinlock is designed to handle thread priority inversion issues. However, OSUninterruptibleSpinlock still busy-waits. If a thread wants to sleep one needs to use an OSMutex.

Do Not Call From

None.

See Also

OSInitSpinLock
OSReleaseSpinLock
OSTryAcquireSpinLock
OSTryAcquireSpinLockWithTimeout
OSUninterruptibleSpinLock_Release
OSUninterruptibleSpinLock_TryAcquire
OSUninterruptibleSpinLock_TryAcquireWithTimeout
OSDisableInterrupts
OSEnableInterrupts
OSRestoreInterrupts
OSIsInterruptEnabled

Revision History

2013/05/08 Automated cleanup pass.
2012/08/01 Cleanup Pass.
2012/04/21 Initial version.


CONFIDENTIAL