1.\" $NetBSD: workqueue.9,v 1.11 2015/10/13 04:22:24 riastradh Exp $ 2.\" 3.\" Copyright (c)2005 YAMAMOTO Takashi, 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.\" ------------------------------------------------------------ 28.Dd October 24, 2011 29.Dt WORKQUEUE 9 30.Os 31.\" ------------------------------------------------------------ 32.Sh NAME 33.Nm workqueue 34.Nd simple do-it-in-thread-context framework 35.\" ------------------------------------------------------------ 36.Sh SYNOPSIS 37.In sys/workqueue.h 38.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 39.Ft int 40.Fn workqueue_create \ 41"struct workqueue **wqp" "const char *name" \ 42"void (*func)(struct work *, void *)" "void *arg" \ 43"pri_t prio" "int ipl" "int flags" 44.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 45.Ft void 46.Fn workqueue_enqueue \ 47"struct workqueue *wq" "struct work *wk" "struct cpu_info *ci" 48.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 49.Ft void 50.Fn workqueue_destroy \ 51"struct workqueue *wq" 52.\" ------------------------------------------------------------ 53.Sh DESCRIPTION 54The 55.Nm 56utility routines are provided to defer work which is needed to be 57processed in a thread context. 58.Pp 59.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 60.Fn workqueue_create 61creates a workqueue. 62It takes the following arguments: 63.Bl -tag -width flags 64.It Fa wqp 65Specify where to store the created workqueue. 66.It Fa name 67The name of the workqueue. 68.It Fa func 69The function to be called for each 70.Fa work . 71.It Fa arg 72An argument to be passed as a second argument of 73.Fa func . 74.It Fa prio 75The priority level for the worker threads. 76.It Fa ipl 77The highest IPL at which this workqueue is used. 78.It Fa flags 79The value of 0 indicates a standard create operation, however the following 80flags may be bitwise ORed together: 81.Bl -tag -width WQ_MPSAFE 82.It Dv WQ_MPSAFE 83Specifies that the workqueue is multiprocessor safe and does its own locking; 84otherwise the kernel lock will be held while processing work. 85.It Dv WQ_PERCPU 86Specifies that the workqueue should have a separate queue for each CPU, 87thus the work could be enqueued on concrete CPUs. 88.El 89.El 90.Pp 91.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 92.Fn workqueue_enqueue 93enqueues the work 94.Fa wk 95into the workqueue 96.Fa wq . 97.Pp 98If the 99.Dv WQ_PERCPU 100flag was set on workqueue creation, the 101.Fa ci 102argument may be used to specify the CPU on which the work should 103be enqueued. 104Also it may be 105.Dv NULL , 106then work will be enqueued on the current CPU. 107If 108.Dv WQ_PERCPU 109flag was not set, 110.Fa ci 111must be 112.Dv NULL . 113.Pp 114The enqueued work will be processed in a thread context. 115A work must not be enqueued again until the callback is called by 116the 117.Nm 118framework. 119.Pp 120.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 121.Fn workqueue_destroy 122destroys a workqueue and frees associated resources. 123The caller should ensure that the workqueue has no work enqueued beforehand. 124.\" ------------------------------------------------------------ 125.Sh RETURN VALUES 126.Fn workqueue_create 127returns 0 on success. 128Otherwise, it returns an 129.Xr errno 2 . 130.\" ------------------------------------------------------------ 131.Sh CODE REFERENCES 132The 133.Nm 134subsystem is implemented within the file 135.Pa sys/kern/subr_workqueue.c . 136.\" ------------------------------------------------------------ 137.Sh SEE ALSO 138.Xr callout 9 , 139.Xr condvar 9 , 140.Xr kthread 9 , 141.Xr softint 9 142