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
Theworkqueue 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.