buf_lock(9r) [osf1 man page]

BUF_LOCK(9r)															      BUF_LOCK(9r)

NAME

       BUF_LOCK - General: Locks the specified I/O buffer

SYNOPSIS

       void BUF_LOCK(
	       struct buf *bp );

ARGUMENTS

       Specifies a pointer to a buf structure.

DESCRIPTION

       The BUF_LOCK routine locks the specified I/O buffer.  The routine masks all disk and tape controller interrupts (by calling the splbio rou-
       tine). It sets the mutual exclusion buffer lock member, b_lock, of the specified buf structure pointer.

       The BUF_LOCK routine then sets the b_flags member of the specified buf structure pointer to B_BUSY to indicate that this  buffer  is  being
       used. Finally, BUF_LOCK resets the CPU priority level (by calling the splx routine).

NOTES

       You  should  design  in	your kernel modules to hold the I/O buffer lock for as short a period of time as possible to allow maximum concur-
       rency. You should also release the I/O buffer lock by calling the BUF_UNLOCK routine before returning from the module's entry point.

RETURN VALUES

       None

SEE ALSO

       Routines: BUF_UNLOCK(9r)

																      BUF_LOCK(9r)

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)