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Some man pages.

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57
man/man3/lock.3
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@ -72,22 +72,16 @@ are spin locks,
.B QLocks
and
.B RWLocks
are different types of queueing rendezvous locks,
are different types of queueing locks,
and
.B Rendezes
are rendezvous points.
.PP
Locks and rendezvous points work in regular programs as
well as programs that use the thread library
Locks and rendezvous points have trivial implementations in programs
not using the thread library
(see
.IR thread (3)).
The thread library replaces the
.IR rendezvous (3)
system call
with its own implementation,
.IR threadrendezvous ,
so that threads as well as processes may be synchronized by locking calls
in threaded programs.
.IR thread (3)),
since such programs have no concurrency.
.PP
Used carelessly, spin locks can be expensive and can easily generate deadlocks.
Their use is discouraged, especially in programs that use the
@ -105,7 +99,7 @@ releases a lock.
.B QLocks
have the same interface but are not spin locks; instead if the lock is taken
.I qlock
will suspend execution of the calling task until it is released.
will suspend execution of the calling thread until it is released.
.PP
Although
.B Locks
@ -199,18 +193,39 @@ atomically decrements the
.B Ref
and returns zero if the resulting value is zero, non-zero otherwise.
.SH SOURCE
.B /usr/local/plan9/src/libc/port/lock.c
.B /usr/local/plan9/src/lib9/qlock.c
.br
.B /usr/local/plan9/src/libc/9sys/qlock.c
.br
.B /usr/local/plan9/src/libthread/ref.c
.SH SEE ALSO
.I rfork
in
.IR fork (3)
.B /usr/local/plan9/src/libthread
.SH BUGS
.B Locks
are not strictly spin locks.
are not always spin locks.
Instead they are usually implemented using the
.I pthreads
library's
.BR pthread_mutex_t ,
whose implementation method is not defined.
.PP
On
.IR pthreads -based
systems, the implementation of
.B Lock
never calls
.I pthread_mutex_destroy
to free the
.BR pthread_mutex_t 's.
This leads to resource leaks on FreeBSD 5
(though not on Linux 2.6, where
.I pthread_mutex_destroy
is a no-op).
.BR
.PP
On systems that do not have a usable
.I pthreads
implementation, the
.B Lock
implementation provided by
.I libthread
is still not exactly a spin lock.
After each unsuccessful attempt,
.I lock
calls