Date: Fri, 14 Feb 2014 15:03:55 +0000 (UTC) From: Andriy Gapon <avg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r261890 - head/share/man/man9 Message-ID: <201402141503.s1EF3tWr087576@svn.freebsd.org>
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Author: avg Date: Fri Feb 14 15:03:55 2014 New Revision: 261890 URL: http://svnweb.freebsd.org/changeset/base/261890 Log: update taskqueue(9) manual page Many thanks to bjk, gjb and pluknet for improvements and suggestions. MFC after: 5 days Sponsored by: HybridCluster Modified: head/share/man/man9/Makefile head/share/man/man9/taskqueue.9 Modified: head/share/man/man9/Makefile ============================================================================== --- head/share/man/man9/Makefile Fri Feb 14 14:44:34 2014 (r261889) +++ head/share/man/man9/Makefile Fri Feb 14 15:03:55 2014 (r261890) @@ -1350,6 +1350,7 @@ MLINKS+=sysctl_ctx_init.9 sysctl_ctx_ent MLINKS+=SYSINIT.9 SYSUNINIT.9 MLINKS+=taskqueue.9 TASK_INIT.9 \ taskqueue.9 TASK_INITIALIZER.9 \ + taskqueue.9 taskqueue_block.9 \ taskqueue.9 taskqueue_cancel.9 \ taskqueue.9 taskqueue_create.9 \ taskqueue.9 taskqueue_create_fast.9 \ @@ -1357,13 +1358,15 @@ MLINKS+=taskqueue.9 TASK_INIT.9 \ taskqueue.9 TASKQUEUE_DEFINE.9 \ taskqueue.9 TASKQUEUE_DEFINE_THREAD.9 \ taskqueue.9 taskqueue_drain.9 \ + taskqueue.9 taskqueue_drain_all.9 \ taskqueue.9 taskqueue_enqueue.9 \ taskqueue.9 taskqueue_enqueue_fast.9 \ taskqueue.9 TASKQUEUE_FAST_DEFINE.9 \ taskqueue.9 TASKQUEUE_FAST_DEFINE_THREAD.9 \ taskqueue.9 taskqueue_free.9 \ taskqueue.9 taskqueue_member.9 \ - taskqueue.9 taskqueue_run.9 + taskqueue.9 taskqueue_run.9 \ + taskqueue.9 taskqueue_unblock.9 MLINKS+=time.9 boottime.9 \ time.9 time_second.9 \ time.9 time_uptime.9 Modified: head/share/man/man9/taskqueue.9 ============================================================================== --- head/share/man/man9/taskqueue.9 Fri Feb 14 14:44:34 2014 (r261889) +++ head/share/man/man9/taskqueue.9 Fri Feb 14 15:03:55 2014 (r261890) @@ -28,7 +28,7 @@ .\" .\" $FreeBSD$ .\" -.Dd December 4, 2012 +.Dd January 24, 2014 .Dt TASKQUEUE 9 .Os .Sh NAME @@ -86,6 +86,12 @@ struct timeout_task; .Fn taskqueue_drain "struct taskqueue *queue" "struct task *task" .Ft void .Fn taskqueue_drain_timeout "struct taskqueue *queue" "struct timeout_task *timeout_task" +.Ft void +.Fn taskqueue_drain_all "struct taskqueue *queue" +.Ft void +.Fn taskqueue_block "struct taskqueue *queue" +.Ft void +.Fn taskqueue_unblock "struct taskqueue *queue" .Ft int .Fn taskqueue_member "struct taskqueue *queue" "struct thread *td" .Ft void @@ -255,6 +261,73 @@ function is used to wait for the schedul There is no guarantee that the task will not be enqueued after call to .Fn taskqueue_drain . +If the caller wants to put the task into a known state, +then before calling +.Fn taskqueue_drain +the caller should use out-of-band means to ensure that the task +would not be enqueued. +For example, if the task is enqueued by an interrupt filter, then +the interrupt could be disabled. +.Pp +The +.Fn taskqueue_drain_all +function is used to wait for all pending and running tasks that +are enqueued on the taskqueue to finish. +The caller must arrange that the tasks are not re-enqueued. +Note that +.Fn taskqueue_drain_all +currently does not handle tasks with delayed enqueueing. +.Pp +The +.Fn taskqueue_block +function blocks the taskqueue. +It prevents any enqueued but not running tasks from being executed. +Future calls to +.Fn taskqueue_enqueue +will enqueue tasks, but the tasks will not be run until +.Fn taskqueue_unblock +is called. +Please note that +.Fn taskqueue_block +does not wait for any currently running tasks to finish. +Thus, the +.Fn taskqueue_block +does not provide a guarantee that +.Fn taskqueue_run +is not running after +.Fn taskqueue_block +returns, but it does provide a guarantee that +.Fn taskqueue_run +will not be called again +until +.Fn taskqueue_unblock +is called. +If the caller requires a guarantee that +.Fn taskqueue_run +is not running, then this must be arranged by the caller. +Note that if +.Fn taskqueue_drain +is called on a task that is enqueued on a taskqueue that is blocked by +.Fn taskqueue_block , +then +.Fn taskqueue_drain +can not return until the taskqueue is unblocked. +This can result in a deadlock if the thread blocked in +.Fn taskqueue_drain +is the thread that is supposed to call +.Fn taskqueue_unblock . +Thus, use of +.Fn taskqueue_drain +after +.Fn taskqueue_block +is discouraged, because the state of the task can not be known in advance. +The same caveat applies to +.Fn taskqueue_drain_all . +.Pp +The +.Fn taskqueue_unblock +function unblocks the previously blocked taskqueue. +All enqueued tasks can be run after this call. .Pp The .Fn taskqueue_member
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