Date: Mon, 29 Sep 2014 19:31:39 GMT From: John Baldwin <jhb@FreeBSD.org> To: Perforce Change Reviews <perforce@FreeBSD.org> Subject: PERFORCE change 1200929 for review Message-ID: <201409291931.s8TJVduX015817@skunkworks.freebsd.org>
next in thread | raw e-mail | index | archive | help
http://p4web.freebsd.org/@@1200929?ac=10 Change 1200929 by jhb@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 ;
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201409291931.s8TJVduX015817>