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npf_worker.c revision 1.1 
      1 /*	$NetBSD: npf_worker.c,v 1.1 2013/06/02 02:20:04 rmind Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2010-2013 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This material is based upon work partially supported by The
      8  * NetBSD Foundation under a contract with Mindaugas Rasiukevicius.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 __KERNEL_RCSID(0, "$NetBSD: npf_worker.c,v 1.1 2013/06/02 02:20:04 rmind Exp $");
     34 
     35 #include <sys/param.h>
     36 #include <sys/types.h>
     37 
     38 #include <sys/mutex.h>
     39 #include <sys/kernel.h>
     40 #include <sys/kthread.h>
     41 
     42 #include "npf_impl.h"
     43 
     44 #define	NPF_MAX_WORKS		4
     45 #define	WORKER_INTERVAL		mstohz(5 * 1000)
     46 
     47 static kmutex_t		worker_lock;
     48 static kcondvar_t	worker_cv;
     49 static kcondvar_t	worker_event_cv;
     50 static lwp_t *		worker_lwp;
     51 static uint64_t		worker_loop;
     52 
     53 static npf_workfunc_t	work_funcs[NPF_MAX_WORKS];
     54 
     55 static void	npf_worker(void *) __dead;
     56 
     57 int
     58 npf_worker_sysinit(void)
     59 {
     60 	mutex_init(&worker_lock, MUTEX_DEFAULT, IPL_SOFTNET);
     61 	cv_init(&worker_cv, "npfgccv");
     62 	cv_init(&worker_event_cv, "npfevcv");
     63 	worker_lwp = (lwp_t *)0xdeadbabe;
     64 	worker_loop = 1;
     65 
     66 	if (kthread_create(PRI_NONE, KTHREAD_MPSAFE | KTHREAD_MUSTJOIN, NULL,
     67 	    npf_worker, NULL, &worker_lwp, "npfgc")) {
     68 		return ENOMEM;
     69 	}
     70 	return 0;
     71 }
     72 
     73 void
     74 npf_worker_sysfini(void)
     75 {
     76 	lwp_t *l = worker_lwp;
     77 
     78 	/* Notify the worker and wait for the exit. */
     79 	mutex_enter(&worker_lock);
     80 	worker_lwp = NULL;
     81 	cv_broadcast(&worker_cv);
     82 	mutex_exit(&worker_lock);
     83 	kthread_join(l);
     84 
     85 	/* LWP has exited, destroy the structures. */
     86 	cv_destroy(&worker_cv);
     87 	cv_destroy(&worker_event_cv);
     88 	mutex_destroy(&worker_lock);
     89 }
     90 
     91 void
     92 npf_worker_signal(void)
     93 {
     94 	mutex_enter(&worker_lock);
     95 	cv_signal(&worker_cv);
     96 	mutex_exit(&worker_lock);
     97 }
     98 
     99 static bool
    100 npf_worker_testset(npf_workfunc_t find, npf_workfunc_t set)
    101 {
    102 	for (u_int i = 0; i < NPF_MAX_WORKS; i++) {
    103 		if (work_funcs[i] == find) {
    104 			work_funcs[i] = set;
    105 			return true;
    106 		}
    107 	}
    108 	return false;
    109 }
    110 
    111 void
    112 npf_worker_register(npf_workfunc_t func)
    113 {
    114 	mutex_enter(&worker_lock);
    115 	npf_worker_testset(NULL, func);
    116 	mutex_exit(&worker_lock);
    117 }
    118 
    119 void
    120 npf_worker_unregister(npf_workfunc_t func)
    121 {
    122 	uint64_t l = worker_loop;
    123 
    124 	mutex_enter(&worker_lock);
    125 	npf_worker_testset(func, NULL);
    126 	while (worker_loop == l) {
    127 		cv_signal(&worker_cv);
    128 		cv_wait(&worker_event_cv, &worker_lock);
    129 	}
    130 	mutex_exit(&worker_lock);
    131 }
    132 
    133 static void
    134 npf_worker(void *arg)
    135 {
    136 	for (;;) {
    137 		const bool finish = (worker_lwp == NULL);
    138 		u_int i = NPF_MAX_WORKS;
    139 		npf_workfunc_t work;
    140 
    141 		/* Run the jobs. */
    142 		while (i--) {
    143 			if ((work = work_funcs[i]) != NULL) {
    144 				work();
    145 			}
    146 		}
    147 
    148 		/* Exit if requested and all jobs are done. */
    149 		if (finish) {
    150 			break;
    151 		}
    152 
    153 		/* Sleep and periodically wake up, unless we get notified. */
    154 		mutex_enter(&worker_lock);
    155 		worker_loop++;
    156 		cv_broadcast(&worker_event_cv);
    157 		cv_timedwait(&worker_cv, &worker_lock, WORKER_INTERVAL);
    158 		mutex_exit(&worker_lock);
    159 	}
    160 	kthread_exit(0);
    161 }
    162