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klock.c revision 1.5 
      1 /*	$NetBSD: klock.c,v 1.5 2012/10/09 13:35:50 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 1.5 2012/10/09 13:35:50 pooka Exp $");
     33 
     34 #include <sys/param.h>
     35 #include <sys/systm.h>
     36 #include <sys/evcnt.h>
     37 
     38 #include <rump/rumpuser.h>
     39 
     40 #include "rump_private.h"
     41 
     42 /*
     43  * giant lock
     44  */
     45 
     46 struct rumpuser_mtx *rump_giantlock;
     47 static int giantcnt;
     48 static struct lwp *giantowner;
     49 
     50 static struct evcnt ev_biglock_fast;
     51 static struct evcnt ev_biglock_slow;
     52 static struct evcnt ev_biglock_recurse;
     53 
     54 void
     55 rump_biglock_init(void)
     56 {
     57 
     58 	evcnt_attach_dynamic(&ev_biglock_fast, EVCNT_TYPE_MISC, NULL,
     59 	    "rump biglock", "fast");
     60 	evcnt_attach_dynamic(&ev_biglock_slow, EVCNT_TYPE_MISC, NULL,
     61 	    "rump biglock", "slow");
     62 	evcnt_attach_dynamic(&ev_biglock_recurse, EVCNT_TYPE_MISC, NULL,
     63 	    "rump biglock", "recurse");
     64 }
     65 
     66 void
     67 rump_kernel_bigwrap(int *nlocks)
     68 {
     69 
     70 	KASSERT(giantcnt > 0 && curlwp == giantowner);
     71 	giantowner = NULL;
     72 	*nlocks = giantcnt;
     73 	giantcnt = 0;
     74 }
     75 
     76 void
     77 rump_kernel_bigunwrap(int nlocks)
     78 {
     79 
     80 	KASSERT(giantowner == NULL);
     81 	giantowner = curlwp;
     82 	giantcnt = nlocks;
     83 }
     84 
     85 void
     86 _kernel_lock(int nlocks)
     87 {
     88 	struct lwp *l = curlwp;
     89 
     90 	while (nlocks) {
     91 		if (giantowner == l) {
     92 			giantcnt += nlocks;
     93 			nlocks = 0;
     94 			ev_biglock_recurse.ev_count++;
     95 		} else {
     96 			if (!rumpuser_mutex_tryenter(rump_giantlock)) {
     97 				rump_unschedule_cpu1(l, NULL);
     98 				rumpuser_mutex_enter_nowrap(rump_giantlock);
     99 				rump_schedule_cpu(l);
    100 				ev_biglock_slow.ev_count++;
    101 			} else {
    102 				ev_biglock_fast.ev_count++;
    103 			}
    104 			giantowner = l;
    105 			giantcnt = 1;
    106 			nlocks--;
    107 		}
    108 	}
    109 }
    110 
    111 void
    112 _kernel_unlock(int nlocks, int *countp)
    113 {
    114 
    115 	if (giantowner != curlwp) {
    116 		KASSERT(nlocks == 0);
    117 		if (countp)
    118 			*countp = 0;
    119 		return;
    120 	}
    121 
    122 	if (countp)
    123 		*countp = giantcnt;
    124 	if (nlocks == 0)
    125 		nlocks = giantcnt;
    126 	if (nlocks == -1) {
    127 		KASSERT(giantcnt == 1);
    128 		nlocks = 1;
    129 	}
    130 	KASSERT(nlocks <= giantcnt);
    131 	while (nlocks--) {
    132 		giantcnt--;
    133 	}
    134 
    135 	if (giantcnt == 0) {
    136 		giantowner = NULL;
    137 		rumpuser_mutex_exit(rump_giantlock);
    138 	}
    139 }
    140 
    141 bool
    142 _kernel_locked_p(void)
    143 {
    144 
    145 	return giantowner == curlwp;
    146 }
    147 
    148 void
    149 rump_user_unschedule(int nlocks, int *countp, void *interlock)
    150 {
    151 
    152 	_kernel_unlock(nlocks, countp);
    153 	/*
    154 	 * XXX: technically we should unschedule_cpu1() here, but that
    155 	 * requires rump_intr_enter/exit to be implemented.
    156 	 */
    157 	rump_unschedule_cpu_interlock(curlwp, interlock);
    158 }
    159 
    160 void
    161 rump_user_schedule(int nlocks, void *interlock)
    162 {
    163 
    164 	rump_schedule_cpu_interlock(curlwp, interlock);
    165 
    166 	if (nlocks)
    167 		_kernel_lock(nlocks);
    168 }
    169