1.\" $NetBSD: workqueue.9,v 1.12 2017/12/28 07:00:52 ozaki-r 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 December 28, 2017 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_wait \ 51"struct workqueue *wq" "struct work *wk" 52.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 53.Ft void 54.Fn workqueue_destroy \ 55"struct workqueue *wq" 56.\" ------------------------------------------------------------ 57.Sh DESCRIPTION 58The 59.Nm 60utility routines are provided to defer work which is needed to be 61processed in a thread context. 62.Pp 63.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 64.Fn workqueue_create 65creates a workqueue. 66It takes the following arguments: 67.Bl -tag -width flags 68.It Fa wqp 69Specify where to store the created workqueue. 70.It Fa name 71The name of the workqueue. 72.It Fa func 73The function to be called for each 74.Fa work . 75.It Fa arg 76An argument to be passed as a second argument of 77.Fa func . 78.It Fa prio 79The priority level for the worker threads. 80.It Fa ipl 81The highest IPL at which this workqueue is used. 82.It Fa flags 83The value of 0 indicates a standard create operation, however the following 84flags may be bitwise ORed together: 85.Bl -tag -width WQ_MPSAFE 86.It Dv WQ_MPSAFE 87Specifies that the workqueue is multiprocessor safe and does its own locking; 88otherwise the kernel lock will be held while processing work. 89.It Dv WQ_PERCPU 90Specifies that the workqueue should have a separate queue for each CPU, 91thus the work could be enqueued on concrete CPUs. 92.El 93.El 94.Pp 95.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 96.Fn workqueue_enqueue 97enqueues the work 98.Fa wk 99into the workqueue 100.Fa wq . 101.Pp 102If the 103.Dv WQ_PERCPU 104flag was set on workqueue creation, the 105.Fa ci 106argument may be used to specify the CPU on which the work should 107be enqueued. 108Also it may be 109.Dv NULL , 110then work will be enqueued on the current CPU. 111If 112.Dv WQ_PERCPU 113flag was not set, 114.Fa ci 115must be 116.Dv NULL . 117.Pp 118The enqueued work will be processed in a thread context. 119A work must not be enqueued again until the callback is called by 120the 121.Nm 122framework. 123.Pp 124.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 125.Fn workqueue_wait 126waits for a specified work 127.Fa wk 128on the workqueue 129.Fa wq 130to finish. 131The caller must ensure that no new work will be enqueued to the workqueue 132beforehand. 133Note that if the workqueue is 134.Dv WQ_PERCPU , 135the caller can enqueue a new work to another queue other than the waiting queue. 136.Pp 137.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 138.Fn workqueue_destroy 139destroys a workqueue and frees associated resources. 140The caller should ensure that the workqueue has no work enqueued beforehand. 141.\" ------------------------------------------------------------ 142.Sh RETURN VALUES 143.Fn workqueue_create 144returns 0 on success. 145Otherwise, it returns an 146.Xr errno 2 . 147.\" ------------------------------------------------------------ 148.Sh CODE REFERENCES 149The 150.Nm 151subsystem is implemented within the file 152.Pa sys/kern/subr_workqueue.c . 153.\" ------------------------------------------------------------ 154.Sh SEE ALSO 155.Xr callout 9 , 156.Xr condvar 9 , 157.Xr kthread 9 , 158.Xr softint 9 159