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klock.c revision 1.3 
      1 /*	$NetBSD: klock.c,v 1.3 2010/12/01 14:59:38 pooka Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 2007-2010 Antti Kantee.  All Rights Reserved.
      5  *
      6  * Development of this software was supported by the
      7  * Finnish Cultural Foundation.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
     19  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     20  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     21  * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
     24  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     28  * SUCH DAMAGE.
     29  */
     30 
     31 #include <sys/cdefs.h>
     32 __KERNEL_RCSID(0, "$NetBSD: klock.c,v 1.3 2010/12/01 14:59:38 pooka Exp $");
     33 
     34 #include <sys/param.h>
     35 #include <sys/systm.h>
     36 
     37 #include <rump/rumpuser.h>
     38 
     39 #include "rump_private.h"
     40 
     41 /*
     42  * giant lock
     43  */
     44 
     45 struct rumpuser_mtx *rump_giantlock;
     46 static int giantcnt;
     47 static struct lwp *giantowner;
     48 
     49 void
     50 rump_kernel_bigwrap(int *nlocks)
     51 {
     52 
     53 	KASSERT(giantcnt > 0 && curlwp == giantowner);
     54 	giantowner = NULL;
     55 	*nlocks = giantcnt;
     56 	giantcnt = 0;
     57 }
     58 
     59 void
     60 rump_kernel_bigunwrap(int nlocks)
     61 {
     62 
     63 	KASSERT(giantowner == NULL);
     64 	giantowner = curlwp;
     65 	giantcnt = nlocks;
     66 }
     67 
     68 void
     69 _kernel_lock(int nlocks)
     70 {
     71 	struct lwp *l = curlwp;
     72 
     73 	while (nlocks) {
     74 		if (giantowner == l) {
     75 			giantcnt += nlocks;
     76 			nlocks = 0;
     77 		} else {
     78 			if (!rumpuser_mutex_tryenter(rump_giantlock)) {
     79 				rump_unschedule_cpu1(l, NULL);
     80 				rumpuser_mutex_enter_nowrap(rump_giantlock);
     81 				rump_schedule_cpu(l);
     82 			}
     83 			giantowner = l;
     84 			giantcnt = 1;
     85 			nlocks--;
     86 		}
     87 	}
     88 }
     89 
     90 void
     91 _kernel_unlock(int nlocks, int *countp)
     92 {
     93 
     94 	if (giantowner != curlwp) {
     95 		KASSERT(nlocks == 0);
     96 		if (countp)
     97 			*countp = 0;
     98 		return;
     99 	}
    100 
    101 	if (countp)
    102 		*countp = giantcnt;
    103 	if (nlocks == 0)
    104 		nlocks = giantcnt;
    105 	if (nlocks == -1) {
    106 		KASSERT(giantcnt == 1);
    107 		nlocks = 1;
    108 	}
    109 	KASSERT(nlocks <= giantcnt);
    110 	while (nlocks--) {
    111 		giantcnt--;
    112 	}
    113 
    114 	if (giantcnt == 0) {
    115 		giantowner = NULL;
    116 		rumpuser_mutex_exit(rump_giantlock);
    117 	}
    118 }
    119 
    120 void
    121 rump_user_unschedule(int nlocks, int *countp, void *interlock)
    122 {
    123 
    124 	_kernel_unlock(nlocks, countp);
    125 	/*
    126 	 * XXX: technically we should unschedule_cpu1() here, but that
    127 	 * requires rump_intr_enter/exit to be implemented.
    128 	 */
    129 	rump_unschedule_cpu_interlock(curlwp, interlock);
    130 }
    131 
    132 void
    133 rump_user_schedule(int nlocks, void *interlock)
    134 {
    135 
    136 	rump_schedule_cpu_interlock(curlwp, interlock);
    137 
    138 	if (nlocks)
    139 		_kernel_lock(nlocks);
    140 }
    141