.Fn vm_map_lock_read

.Fn vm_map_lock_read

macro obtains a read-lock on

macro obtains a read-lock on

.Fa map .

.Fa map .

.Pp

.Pp

The

The

.Fn vm_map_unlock_read

.Fn vm_map_unlock_read

.Fa map .

.Fa map .

It returns FALSE if the lock cannot be immediately acquired;

It returns FALSE if the lock cannot be immediately acquired;

otherwise return TRUE with the lock acquired.

otherwise return TRUE with the lock acquired.

.Pp

.Pp

The

The

.Fn vm_map_lock_upgrade

.Fn vm_map_lock_upgrade

macro attempts to atomically upgrade a read-lock on

macro attempts to atomically upgrade a read-lock on

.Fa map

.Fa map

to an exclusive lock.

to an exclusive lock.

.Pp

.Pp

The

The

.Fn vm_map_lock_downgrade

.Fn vm_map_lock_downgrade

macro attempts to downgrade an exclusive lock on

macro attempts to downgrade an exclusive lock on

.Fa map

.Fa map

to a read-lock.

to a read-lock.

.Sh IMPLEMENTATION NOTES

.Sh IMPLEMENTATION NOTES

Currently, all of the locking macros implement their locks as sleep locks.

Currently, all of the locking macros implement their locks as sleep locks.

.Sh SEE ALSO

.Sh SEE ALSO