kern/lock_mtx.h Kernel.framework

Allocates a mutex and initializes it in the manner of lck_mtx_init with the given group and attributes. The result is freed with lck_mtx_free.

Initializes a mutex, associating it with the given lock group and taking a reference on the group. A NULL attribute selects the defaults; LCK_ATTR_DEBUG in the attributes enables profiling for the lock. Mutexes are blocking locks with adaptive spin and priority inheritance; a destroyed or waited-on mutex must be re-initialized before reuse.

Locks the mutex for the current thread, blocking (after an adaptive spin) if it is owned by another thread. Contended acquisitions use turnstiles, propagating the waiters' priority to the owner. Must not be called from interrupt context; recursive acquisition by the owner is a deadlock/panic.

Unlocks the mutex, waking or handing the lock to a waiting thread and undoing any priority inheritance. Must be called by the owning thread.

Destroys a mutex initialized with lck_mtx_init, marking it unusable (LCK_MTX_TAG_DESTROYED) and dropping its reference on the lock group. Panics if the mutex still has waiters or is in an invalid state. Does not free the memory; for mutexes obtained from lck_mtx_alloc_init use lck_mtx_free.

Destroys a mutex allocated by lck_mtx_alloc_init and frees its memory, dropping the reference on the lock group.

Atomically releases the mutex and waits for the specified event, in the manner of assert_wait plus thread_block; on wakeup the mutex is re-acquired unless LCK_SLEEP_UNLOCK is set. lck_sleep_action may include: LCK_SLEEP_DEFAULT release and re-acquire the lock LCK_SLEEP_UNLOCK return with the lock released LCK_SLEEP_SPIN re-acquire in spin mode LCK_SLEEP_SPIN_ALWAYS re-acquire in spin-always mode LCK_SLEEP_PROMOTED_PRI hold a priority floor for the sleeping thread Returns the wait result (THREAD_AWAKENED, THREAD_TIMED_OUT, THREAD_INTERRUPTED, ...) per the interruptible argument. Panics on invalid action bits.

As lck_mtx_sleep, but the wait is bounded by an absolute deadline in mach_absolute_time units (via assert_wait_deadline); the wait result is THREAD_TIMED_OUT if the deadline expires before wakeup.

Asserts the ownership state of the mutex relative to the current thread: panics if type is LCK_MTX_ASSERT_OWNED and the current thread does not own the lock, or if type is LCK_MTX_ASSERT_NOTOWNED and it does. Panics on any other type value.

Asserts that the current thread owns the mutex, which may be held in spin mode (as after lck_mtx_lock_spin); panics otherwise. Wrapped by the LCK_MTX_ASSERT_OWNED_SPIN macro, compiled in only under MACH_ASSERT/DEBUG kernels. Implementation not present in the available xnu sources; semantics inferred from the header and the lck_mtx_assert family.