LOCK(D3)LOCK(D3)NAMELOCK - acquire a basic lock
SYNOPSIS
#include <sys/types.h>
#include <sys/ksynch.h>
#include <sys/ddi.h>
int LOCK(lock_t *lockp, pl_t pl);
Arguments
lockp Pointer to the basic lock to be acquired.
pl The interrupt priority level to be set while the lock is held
by the caller.
DESCRIPTIONLOCK sets the interrupt priority level in accordance with the value
specified by pl and acquires the lock specified by lockp. If the lock is
not immediately available, the caller will busy-wait until the lock is
available.
Return Values
Upon acquiring the lock, LOCK returns the previous mask for use by
UNLOCK. Your driver should treat this return integer as an "opaque"
value and should not try to compare it with any other value or perform
any operation on it.
USAGE
Because some implementations require that interrupts that might attempt
to acquire the lock be blocked on the processor on which the lock is
held, portable drivers must specify a pl value that is sufficient to
block out any interrupt handler that might attempt to acquire this lock.
See the description of the min_pl argument to LOCK_ALLOC(D3) for
additional discussion and a list of the valid values for pl.
Level
Base or Interrupt.
Synchronization Constraints
Driver-defined sleep locks may be held across calls to this function.
Driver-defined basic locks and read/write locks may be held across calls
to this function subject to the hierarchy -- but basic locks must be
unlocked in the reverse order in which they were acquired (first-in,
last-out).
Warnings
Basic locks are not recursive. A call to LOCK attempting to acquire a
lock that is currently held by the calling context will result in
deadlock.
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LOCK(D3)LOCK(D3)
Calls to LOCK should honor the hierarchy ordering to avoid deadlock.
When called from interrupt level, the pl argument must not specify a
priority level below the level at which the interrupt handler is running.
REFERENCESLOCK_ALLOC(D3), LOCK_DEALLOC(D3), LOCK_DESTROY(D3), LOCK_INIT(D3),
TRYLOCK(D3), UNLOCK(D3).
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