151 lines
4.8 KiB
Groff
151 lines
4.8 KiB
Groff
.\" $NetBSD: workqueue.9,v 1.8 2009/08/04 18:59:05 wiz Exp $
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.\"
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.\" Copyright (c)2005 YAMAMOTO Takashi,
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" ------------------------------------------------------------
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.Dd August 3, 2009
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.Dt WORKQUEUE 9
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.Os
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.\" ------------------------------------------------------------
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.Sh NAME
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.Nm workqueue
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.Nd simple do-it-in-thread-context framework
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.\" ------------------------------------------------------------
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.Sh SYNOPSIS
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.In sys/workqueue.h
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.Ft int
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.Fn workqueue_create \
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"struct workqueue **wqp" "const char *name" \
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"void (*func)(struct work *, void *)" "void *arg" \
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"pri_t prio" "int ipl" "int flags"
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.Ft void
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.Fn workqueue_enqueue \
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"struct workqueue *wq" "struct work *wk" "struct cpu_info *ci"
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.Ft void
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.Fn workqueue_destroy \
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"struct workqueue *wq"
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.\" ------------------------------------------------------------
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.Sh DESCRIPTION
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The
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.Nm
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utility routines are provided to defer work which is needed to be
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processed in a thread context.
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.Pp
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.Fn workqueue_create
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creates a workqueue.
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It takes the following arguments:
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.Bl -tag -width flags
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.It Fa wqp
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Specify where to store the created workqueue.
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.It Fa name
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The name of the workqueue.
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.It Fa func
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The function to be called for each
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.Fa work .
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.It Fa arg
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An argument to be passed as a second argument of
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.Fa func .
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.It Fa prio
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The process priority to be used when sleeping to wait requests.
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.It Fa ipl
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The highest IPL at which this workqueue is used.
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.It Fa flags
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The value of 0 indicates a standard create operation, however the following
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flags may be bitwise ORed together:
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.Bl -tag -width WQ_MPSAFE
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.It Dv WQ_MPSAFE
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Specifies that the workqueue is multiprocessor safe and does its own locking,
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otherwise the kernel lock will be held while work will be processed.
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.It Dv WQ_PERCPU
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Specifies that the workqueue should have a separate queue for each CPU,
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thus the work could be enqueued on concrete CPUs.
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.El
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.El
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.Pp
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.Fn workqueue_enqueue
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enqueues the work
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.Fa wk
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into the workqueue
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.Fa wq .
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.Pp
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If the
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.Dv WQ_PERCPU
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flag was set on workqueue creation, the
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.Fa ci
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argument may be used to specify the CPU on which the work should
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be enqueued.
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Also it may be
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.Dv NULL ,
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then work will be enqueued on the current CPU.
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If
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.Dv WQ_PERCPU
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flag was not set,
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.Fa ci
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must be
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.Dv NULL .
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.Pp
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The enqueued work will be processed in a thread context.
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A work must not be enqueued again until the callback is called by
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the
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.Nm
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framework.
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.Pp
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.Fn workqueue_destroy
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destroys a workqueue and frees associated resources.
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The caller should ensure that the workqueue has no work enqueued beforehand.
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.\" ------------------------------------------------------------
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.Sh RETURN VALUES
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.Fn workqueue_create
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returns 0 on success.
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Otherwise, it returns an
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.Xr errno 2 .
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.\" ------------------------------------------------------------
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.Sh CODE REFERENCES
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This section describes places within the
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.Nx
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source tree where actual code implementing the
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.Nm
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subsystem
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can be found.
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All pathnames are relative to
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.Pa /usr/src .
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.Pp
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The
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.Nm
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subsystem is implemented within the file
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.Pa sys/kern/subr_workqueue.c .
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.\" ------------------------------------------------------------
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.Sh SEE ALSO
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.Xr callout 9 ,
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.Xr condvar 9 ,
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.Xr kthread 9 ,
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.Xr softint 9
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