NAME
workqueue —
simple
do-it-in-thread-context framework
SYNOPSIS
#include <sys/workqueue.h>
int
workqueue_create(
struct
workqueue **wqp,
const char
*name,
void (*func)(struct
work *, void *),
void
*arg,
pri_t prio,
int ipl,
int flags);
void
workqueue_enqueue(
struct
workqueue *wq,
struct work
*wk,
struct cpu_info
*ci);
void
workqueue_wait(
struct
workqueue *wq,
struct work
*wk);
void
workqueue_destroy(
struct
workqueue *wq);
DESCRIPTION
The
workqueue utility routines are provided to defer work
which is needed to be processed in a thread context.
workqueue_create() creates a workqueue. It takes the following
arguments:
-
-
- wqp
- Specify where to store the created workqueue.
-
-
- name
- The name of the workqueue.
-
-
- func
- The function to be called for each
work.
-
-
- arg
- An argument to be passed as a second argument of
func.
-
-
- prio
- The priority level for the worker threads.
-
-
- ipl
- The highest IPL at which this workqueue is used.
-
-
- flags
- The value of 0 indicates a standard create operation,
however the following flags may be bitwise ORed together:
-
-
WQ_MPSAFE
- Specifies that the workqueue is multiprocessor safe and
does its own locking; otherwise the kernel lock will be held while
processing work.
-
-
WQ_PERCPU
- Specifies that the workqueue should have a separate
queue for each CPU, thus the work could be enqueued on concrete
CPUs.
workqueue_enqueue() enqueues the work
wk
into the workqueue
wq.
If the
WQ_PERCPU
flag was set on workqueue creation, the
ci argument may be used to specify the CPU on which the
work should be enqueued. Also it may be
NULL
, then
work will be enqueued on the current CPU. If
WQ_PERCPU
flag was not set,
ci must be
NULL
.
The enqueued work will be processed in a thread context. A work must not be
enqueued again until the callback is called by the
workqueue
framework.
workqueue_wait() waits for a specified work
wk on the workqueue
wq to finish.
The caller must ensure that no new work will be enqueued to the workqueue
beforehand. Note that if the workqueue is
WQ_PERCPU
,
the caller can enqueue a new work to another queue other than the waiting
queue.
workqueue_destroy() destroys a workqueue and frees associated
resources. The caller should ensure that the workqueue has no work enqueued
beforehand.
RETURN VALUES
workqueue_create() returns 0 on success. Otherwise, it returns
an
errno(2).
CODE REFERENCES
The
workqueue subsystem is implemented within the file
sys/kern/subr_workqueue.c.
SEE ALSO
callout(9),
condvar(9),
kthread(9),
softint(9)