Motorola MCP750 Specifications download pdf (Page 186)

evice Driver Programming

11-12

Upon acquiring the lock, the RW_TRYRDLOCK routine returns the previous priority level.

If the lock is not acquired, the RW_TRYRDLOCK routine returns the value invpl (invalid

IPL).

To acquire a read/write lock in write mode, invoke the RW_WRLOCK routine.

#include <sys/types.h>

#include <sys/ksynch.h>

#include <sys/ddi.h>

pl_t RW_WRLOCK(lockp, pl)

rwlock_t *lockp;

pl_t pl;

where:

lockp is a pointer to the read/write lock to be acquired.

pl is the interrupt priority level to be set while the lock is held by the caller.

Upon acquiring the lock, the RW_WRLOCK routine returns the previous priority level.

To try to acquire a read/write lock in read mode without causing a busy wait if the lock is

unavailable, invoke the RW_TRYWRLOCK routine.

#include <sys/types.h>

#include <sys/ksynch.h>

#include <sys/ddi.h>

pl_t RW_TRYWRLOCK(lockp, pl)

rwlock_t *lockp;

pl_t pl

;

where:

lockp is a pointer to the read/write lock to be acquired.

pl is the interrupt priority level to be set while the lock is held by the caller.

Upon acquiring the lock, the RW_TRYWRLOCK routine returns the previous priority level.

If the lock is not acquired, the RW_TRYWRLOCK routine returns the value invpl (invalid

IPL).

To release a read/write lock, there is a single routine: RW_UNLOCK.

#include <sys/types.h>

#include <sys/ksynch.h>

#include <sys/ddi.h>

void RW_UNLOCK(lockp

pl)

rwlock_t *lockp;

pl_t pl

;

where:

lockp is a pointer to the read/write lock to be released.

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Motorola MCP750 Specifications Page 186