Motorola MCP750 Specifications download pdf (Page 191)

Multithreading a Device Drive

11-1

#include <sys/types.h>

#include <sys/ksynch.h>

#include <sys/ddi.h>

bool_t SLEEP_LOCKOWNED(lockp)

lock_t *lockp;

where:

lockp is a pointer to the sleep lock to be queried.

The SLEEP_LOCKOWNED routine returns TRUE (a non-zero value) if the lock is currently

held by the calling context or FALSE (zero) if the lock is not currently held by the calling

context.

To release a sleep lock, use the SLEEP_UNLOCK routine:

#include <sys/ksynch.h>

#include <sys/ddi.h>

void SLEEP_UNLOCK(lockp)

lock_t *lockp;

where:

lockp is a pointer to the sleep lock to be unlocked.

The SLEEP_UNLOCK routine has no return value.

Finally, to deallocate an instance of a sleep lock, use the SLEEP_DEALLOC routine:

#include <sys/ksynch.h>

#include <sys/ddi.h>

void SLEEP_DEALLOC(lockp)

lock_t *lockp;

where:

lockp is a pointer to the sleep lock to be deallocated.

The SLEEP_DEALLOC routine has no return value.

Sleep locks automatically support priority inheritance. This means that an LWP that suc-

cessfully locks a sleep lock executes at a priority at least as high as the priorities of all

LWPs blocked on the sleep lock. When unlocked, the locking LWP’s priority is restored to

its original value. Priority inheritance is a means of preventing priority inversion which

could be a critical problem on real-time systems.

For additional information on the sleep lock interfaces, refer to the corresponding system

manual pages.

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Motorola MCP750 Specifications Page 191