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.\" Copyright (c) 2003 Bruce M Simpson <bms@spc.org>
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.\" $FreeBSD: src/share/man/man9/vm_map_lock.9,v 1.5.2.1.6.1 2010/12/21 17:09:25 kensmith Exp $
.\"
.Dd July 19, 2003
.Dt VM_MAP_LOCK 9
.Os
.Sh NAME
.Nm vm_map_lock ,
.Nm vm_map_unlock ,
.Nm vm_map_lock_read ,
.Nm vm_map_unlock_read ,
.Nm vm_map_trylock ,
.Nm vm_map_trylock_read ,
.Nm vm_map_lock_upgrade ,
.Nm vm_map_lock_downgrade
.Nd vm_map locking macros
.Sh SYNOPSIS
.In sys/param.h
.In vm/vm.h
.In vm/vm_map.h
.Ft void
.Fn vm_map_lock "vm_map_t map"
.Ft void
.Fn vm_map_unlock "vm_map_t map"
.Ft void
.Fn vm_map_lock_read "vm_map_t map"
.Ft void
.Fn vm_map_unlock_read "vm_map_t map"
.Ft int
.Fn vm_map_trylock "vm_map_t map"
.Ft int
.Fn vm_map_trylock_read "vm_map_t map"
.Ft int
.Fn vm_map_lock_upgrade "vm_map_t map"
.Ft int
.Fn vm_map_lock_downgrade "vm_map_t map"
.Sh DESCRIPTION
The
.Fn vm_map_lock
macro obtains an exclusive lock on
.Fa map .
.Pp
The
.Fn vm_map_unlock
macro releases an exclusive lock on
.Fa map .
.Pp
The
.Fn vm_map_lock_read
macro obtains a read-lock on
.Fa map .
.Pp
The
.Fn vm_map_unlock_read
macro releases a read-lock on
.Fa map .
.Pp
The
.Fn vm_map_trylock
macro attempts to obtain an exclusive lock on
.Fa map .
It returns FALSE if the lock cannot be immediately acquired;
otherwise return TRUE with the lock acquired.
.Pp
The
.Fn vm_map_trylock_read
macro attempts to obtain a read-lock on
.Fa map .
It returns FALSE if the lock cannot be immediately acquired;
otherwise return TRUE with the lock acquired.
.Pp
The
.Fn vm_map_lock_upgrade
macro attempts to atomically upgrade a read-lock on
.Fa map
to an exclusive lock.
.Pp
The
.Fn vm_map_lock_downgrade
macro attempts to downgrade an exclusive lock on
.Fa map
to a read-lock.
.Sh IMPLEMENTATION NOTES
Currently, all of the locking macros implement their locks as sleep locks.
.Sh SEE ALSO
.Xr vm_map 9
.Sh AUTHORS
This manual page was written by
.An Bruce M Simpson Aq bms@spc.org .