Home | History | Annotate | Line # | Download | only in membar
t_spinlock.c revision 1.5 
      1 /*	$NetBSD: t_spinlock.c,v 1.5 2025/05/02 22:30:44 riastradh Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2022 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     17  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     18  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     19  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     20  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     26  * POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #include <sys/cdefs.h>
     30 __RCSID("$NetBSD: t_spinlock.c,v 1.5 2025/05/02 22:30:44 riastradh Exp $");
     31 
     32 #include <sys/types.h>
     33 
     34 #include <sys/atomic.h>
     35 #include <sys/param.h>
     36 #include <sys/sysctl.h>
     37 
     38 #include <assert.h>
     39 #include <atf-c.h>
     40 #include <err.h>
     41 #include <errno.h>
     42 #include <inttypes.h>
     43 #include <pthread.h>
     44 #include <stdint.h>
     45 #include <stdio.h>
     46 #include <unistd.h>
     47 
     48 #ifdef	BROKEN_ACQUIRE
     49 #undef	membar_acquire
     50 #define	membar_acquire()	asm volatile("" ::: "memory")
     51 #endif	/* BROKEN_ACQUIRE */
     52 
     53 #ifdef	BROKEN_RELEASE
     54 #undef	membar_release
     55 #define	membar_release()	asm volatile("" ::: "memory")
     56 #endif	/* BROKEN_RELEASE */
     57 
     58 volatile sig_atomic_t times_up;
     59 
     60 volatile unsigned lockbit __aligned(COHERENCY_UNIT);
     61 
     62 volatile struct {
     63 	uint64_t v;
     64 } __aligned(COHERENCY_UNIT) C[8];
     65 uint64_t TC[2];
     66 
     67 static void
     68 lock(void)
     69 {
     70 
     71 	while (atomic_swap_uint(&lockbit, 1))
     72 		continue;
     73 	membar_acquire();
     74 }
     75 
     76 static void
     77 unlock(void)
     78 {
     79 
     80 	membar_release();
     81 #ifdef __HAVE_HASHLOCKED_ATOMICS
     82 	(void)atomic_cas_uint(&lockbit, 1, 0);
     83 #else
     84 	lockbit = 0;
     85 #endif
     86 }
     87 
     88 static void *
     89 thread(void *cookie)
     90 {
     91 	unsigned me = (unsigned)(uintptr_t)cookie;
     92 	uint64_t C_local = 0, C0[__arraycount(C)];
     93 	unsigned i;
     94 
     95 	while (!times_up) {
     96 		C_local++;
     97 		lock();
     98 		for (i = 0; i < __arraycount(C); i++)
     99 			C0[i] = C[i].v;
    100 		__insn_barrier();
    101 		for (i = __arraycount(C); i --> 0;)
    102 			C[i].v = C0[i] + 1;
    103 		unlock();
    104 	}
    105 
    106 	TC[me] = C_local;
    107 
    108 	return NULL;
    109 }
    110 
    111 ATF_TC(spinlock);
    112 ATF_TC_HEAD(spinlock, tc)
    113 {
    114 	atf_tc_set_md_var(tc, "descr",
    115 	    "Verify membar_acquire/release work for spin locks");
    116 }
    117 ATF_TC_BODY(spinlock, tc)
    118 {
    119 	pthread_t t[2];
    120 	unsigned i;
    121 	int ncpu;
    122 	size_t ncpulen = sizeof(ncpu);
    123 	int error;
    124 
    125 	alarm(10);
    126 
    127 	if (sysctlbyname("hw.ncpu", &ncpu, &ncpulen, NULL, 0) == -1)
    128 		atf_tc_fail("hw.ncpu: (%d) %s", errno, strerror(errno));
    129 	assert(ncpulen == sizeof(ncpu));
    130 	if (ncpu == 1)
    131 		atf_tc_skip("membar tests are only for multicore systems");
    132 
    133 #ifdef __powerpc__
    134 	atf_tc_expect_fail("port-powerpc/59386: t_spinlock test is failing");
    135 #endif
    136 
    137 	for (i = 0; i < 2; i++) {
    138 		error = pthread_create(&t[i], NULL, &thread,
    139 		    (void *)(uintptr_t)i);
    140 		if (error)
    141 			errc(1, error, "pthread_create");
    142 	}
    143 	sleep(5);
    144 	times_up = 1;
    145 	for (i = 0; i < 2; i++) {
    146 		error = pthread_join(t[i], NULL);
    147 		if (error)
    148 			errc(1, error, "pthread_join");
    149 	}
    150 	for (i = 0; i < __arraycount(C); i++) {
    151 		ATF_CHECK_MSG(C[i].v == TC[0] + TC[1], "%d: "
    152 		    "%"PRIu64" != %"PRIu64" + %"PRIu64" (off by %"PRIdMAX")",
    153 		    i, C[i].v, TC[0], TC[1], TC[0] + TC[1] - C[i].v);
    154 	}
    155 }
    156 
    157 ATF_TP_ADD_TCS(tp)
    158 {
    159 
    160 	ATF_TP_ADD_TC(tp, spinlock);
    161 	return atf_no_error();
    162 }
    163