NAME
workq_add_task,
workq_queue_task,
workq_create, workq_destroy
— work queues
SYNOPSIS
#include
<sys/workq.h>
int
workq_add_task(struct
workq *wq, int
flags, void (*func)(void
*, void *), void
*arg1, void
*arg2);
void
workq_queue_task(struct
workq *wq, struct
workq_task *wqt, int
flags, void (*func)(void
*, void *), void
*arg1, void
*arg2);
struct workq *
workq_create(const
char *name, int
maxthreads, int
ipl);
void
workq_destroy(struct
workq *wq);
DESCRIPTION
The workq framework API provides a mechanism to defer tasks to a process context when it is impossible to run such a task in the current context.
workq_add_task()
adds a task to the workq specified by the wq argument.
If wq is NULL the task will be
run by the kernel's generic work queue. Tasks in the kernel's generic work
queue should not run for long periods of time, they should use their own
workq for task processing. A task is specified by the
func argument, and will be called with
arg1 and arg2. Two arguments are
allowed to provide additional flexibility to the called function. In many
cases, one may wish to perform an action on a target. Two arguments allow
both target and action to be passed without the need for a wrapper struct to
contain them in a single argument. The flags argument
specifies creation and runtime characteristics of the task. The possible
flags are:
WQ_WAITOK- Wait for resources to become available. If resources are not available and
this flag is not set then
workq_add_task() will returnENOMEM.
workq_queue_task()
adds a task to the workq specified by the wq argument,
using the memory provided by the wqt argument to store
that task's entry on the workq. The flags,
func, arg1, and
arg2 arguments are the same as those in the
workq_add_task() function. However, because the
caller is responsible for providing the memory needed to store the task on
the workq, workq_queue_task() is guaranteed to
succeed.
workq_create()
creates a workq to be used when tasks would unnecessarily block the kernel
workq. The name argument specifies the name of the
kernel threads that run the tasks. maxthreads
specifies the maximum number of worker threads that will service the work
queue. ipl specifies the interrupt protection level at
which the workq can be safely used. See
spl(9) for a list of the IPLs.
workq_destroy()
causes the resources associated with a previously created workq to be freed.
It will wait till all the tasks in the work queue are completed before
returning.
workq_add_task(),
workq_create(), and
workq_destroy() can be called during
autoconf(9) or from process context.
workq_add_task() can additionally be called from
interrupt context if WQ_WAITOK is not specified.
SEE ALSO
HISTORY
The workq framework was originally written by Ted Unangst <tedu@openbsd.org>, and heavily influenced by arguments with David Gwynne <dlg@openbsd.org>. The workq framework first appeared in OpenBSD 4.2.