PERFORCE change 1200929 for review

[John Baldwin]

http://p4web.freebsd.org/@@1200929?ac=10

Change 1200929 by jhb at jhb_ralph on 2014/09/29 19:31:34

	More edits.

Affected files ...

.. //depot/projects/smpng/share/man/man9/timeout.9#16 edit

Differences ...

==== //depot/projects/smpng/share/man/man9/timeout.9#16 (text+ko) ====

@@ -132,8 +132,8 @@
 This is normally done by rescheduling the subsequent call within the called
 function.
 .Pp
-Callout functions are not permitted to sleep.
-They may not acquire any sleepable locks,
+Callout functions must not sleep.
+They may not acquire sleepable locks,
 wait on condition variables,
 perform blocking allocation requests,
 or invoke any other action that might sleep.
@@ -172,19 +172,16 @@
 or
 .Fa rw
 parameter.
+The associated lock must be held while stopping or rescheduling the
+callout.
 The callout subsystem acquires the associated lock before calling the
-callout function.
-The subsystem then checks if the pending callout was cancelled
-while it waited for the associated lock.
-If the callout was cancelled,
+callout function and releases it after the function returns.
+If the callout was cancelled while the callout subsystem waited for the
+associated lock,
 the callout function is not called and the associated lock is released.
-If the callout was not cancelled,
-the callout function is called and the associated lock is released by the
-subsystem after the callout function returns.
-The callout must only be cancelled or rescheduled while holding the
-associated lock.
-This guarantees that stopping or rescheduling a callout associated with a
-lock will not race with the callout function itself.
+This guarantees that stopping or rescheduling the callout will not race with
+the callout function itself because the associated lock must be held to
+stop or reschedule the callout.
 .Pp
 Only regular mutexes may be used with
 .Fn callout_init_mtx ;