lock_read(9r)															     lock_read(9r)

NAME

       lock_read - General: Asserts a complex lock with read-only access

SYNOPSIS

       #include <kern/lock.h>

       void lock_read(
	       lock_t lock_structptr );

ARGUMENTS

       Specifies  a  pointer  to  the  complex	lock structure, lock. This is the lock structure associated with the resource on which you want to
       assert a complex lock with read-only access. The lock structure is an opaque data structure; that is, its associated members are referenced
       and manipulated by the operating system and not by the user of the complex lock mechanism.

DESCRIPTION

       The  lock_read  routine	asserts  a  lock  with read-only access for the resource associated with the specified lock structure pointer. The
       lock_read routine allows multiple kernel threads to access the resource read-only at the same time. When a read lock is asserted, the  pro-
       tected resource is guaranteed not to change.

       To release a previously asserted read lock, call the lock_done routine.

NOTES

       You must call lock_init (once only) prior to calling lock_read to initialize the lock structure pointer for the resource.  A resource, from
       the kernel module's standpoint, is data that more than one kernel thread can manipulate. You can store the resource in global variables and
       in data structure members.

RETURN VALUES

       None

FILES

SEE ALSO

       Routines: lock_done(9r), lock_terminate(9r), lock_try_read(9r), lock_try_write(9r), lock_write(9r)

       Data Structures: lock(9s)

																     lock_read(9r)