Implement a simple UMA SMR stress testing tool.

tools/uma/smrstress/Makefile

@@ -0,0 +1,8 @@
+#
+# $FreeBSD$
+#
+
+KMOD= smrstress
+SRCS= smrstress.c
+
+.include <bsd.kmod.mk>

tools/uma/smrstress/smrstress.c

@@ -0,0 +1,227 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2020 Jeffrey Roberson <jeff@FreeBSD.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice unmodified, this list of conditions, and the following
+ *    disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ *
+ */
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/libkern.h>
+#include <sys/module.h>
+#include <sys/mutex.h>
+#include <sys/proc.h>
+#include <sys/kthread.h>
+#include <sys/conf.h>
+#include <sys/mbuf.h>
+#include <sys/smp.h>
+#include <sys/smr.h>
+
+#include <vm/uma.h>
+
+#include <machine/stdarg.h>
+
+static uma_zone_t smrs_zone;
+static smr_t smrs_smr;
+
+static int smrs_cpus;
+static int smrs_writers;
+static int smrs_started;
+static int smrs_iterations = 10000000;
+static int smrs_failures = 0;
+static volatile int smrs_completed;
+
+struct smrs {
+	int		generation;
+	volatile u_int	count;
+};
+
+uintptr_t smrs_current;
+
+static void
+smrs_error(struct smrs *smrs, const char *fmt, ...)
+{
+	va_list ap;
+
+	atomic_add_int(&smrs_failures, 1);
+	printf("SMR ERROR: wr_seq %d, rd_seq %d, c_seq %d, generation %d, count %d ",
+	    smrs_smr->c_shared->s_wr_seq, smrs_smr->c_shared->s_rd_seq,
+	    zpcpu_get(smrs_smr)->c_seq, smrs->generation, smrs->count);
+	va_start(ap, fmt);
+	(void)vprintf(fmt, ap);
+	va_end(ap);
+}
+
+static void
+smrs_read(void)
+{
+	struct smrs *cur;
+	int cnt;
+
+	/* Wait for the writer to exit. */
+	while (smrs_completed == 0) {
+		smr_enter(smrs_smr);
+		cur = (void *)atomic_load_ptr(&smrs_current);
+		if (cur->generation == -1)
+			smrs_error(cur, "read early: Use after free!\n");
+		atomic_add_int(&cur->count, 1);
+		DELAY(100);
+		cnt = atomic_fetchadd_int(&cur->count, -1);
+		if (cur->generation == -1)
+			smrs_error(cur, "read late: Use after free!\n");
+		else if (cnt <= 0)
+			smrs_error(cur, "Invalid ref\n");
+		smr_exit(smrs_smr);
+		maybe_yield();
+	}
+}
+
+static void
+smrs_write(void)
+{
+	struct smrs *cur;
+	int i;
+
+	for (i = 0; i < smrs_iterations; i++) {
+		cur = uma_zalloc_smr(smrs_zone, M_WAITOK);
+		cur = (void *)atomic_swap_ptr(&smrs_current, (uintptr_t)cur);
+		uma_zfree_smr(smrs_zone, cur);
+	}
+}
+
+static void
+smrs_thread(void *arg)
+{
+	int rw = (intptr_t)arg;
+
+	if (rw < smrs_writers)
+		smrs_write();
+	else
+		smrs_read();
+	atomic_add_int(&smrs_completed, 1);
+}
+
+static void
+smrs_start(void)
+{
+	struct smrs *cur;
+	int i;
+
+	smrs_cpus = mp_ncpus;
+	if (mp_ncpus > 3)
+		smrs_writers = 2;
+	else
+		smrs_writers = 1;
+	smrs_started = smrs_cpus;
+	smrs_completed = 0;
+	atomic_store_rel_ptr(&smrs_current,
+	    (uintptr_t)uma_zalloc_smr(smrs_zone, M_WAITOK));
+	for (i = 0; i < smrs_started; i++)
+		kthread_add((void (*)(void *))smrs_thread,
+		    (void *)(intptr_t)i, curproc, NULL, 0, 0, "smrs-%d", i);
+
+	while (smrs_completed != smrs_started)
+		pause("prf", hz/2);
+
+	cur = (void *)smrs_current;
+	smrs_current = (uintptr_t)NULL;
+	uma_zfree_smr(smrs_zone, cur);
+
+	printf("Completed %d loops with %d failures\n",
+	    smrs_iterations, smrs_failures);
+}
+
+static int
+smrs_ctor(void *mem, int size, void *arg, int flags)
+{
+	static int smr_generation = 0;
+	struct smrs *smrs = mem;
+
+	if (smrs->generation != -1 && smrs->generation != 0)
+		smrs_error(smrs, "ctor: Invalid smr generation on ctor\n");
+	else if (smrs->count != 0)
+		smrs_error(smrs, "ctor: Invalid count\n");
+	smrs->generation = ++smr_generation;
+
+	return (0);
+}
+
+
+static void
+smrs_dtor(void *mem, int size, void *arg)
+{
+	struct smrs *smrs = mem;
+
+	if (smrs->generation == -1)
+		smrs_error(smrs, "dtor: Invalid generation");
+	smrs->generation = -1;
+	if (smrs->count != 0)
+		smrs_error(smrs, "dtor: Invalid count\n");
+}
+
+
+static void
+smrs_init(void)
+{
+
+	smrs_zone = uma_zcreate("smrs", sizeof(struct smrs),
+	    smrs_ctor,  smrs_dtor, NULL, NULL, UMA_ALIGN_PTR,
+	    UMA_ZONE_SMR | UMA_ZONE_ZINIT);
+        smrs_smr = uma_zone_get_smr(smrs_zone);
+}
+
+static void
+smrs_fini(void)
+{
+
+	uma_zdestroy(smrs_zone);
+}
+
+static int
+smrs_modevent(module_t mod, int what, void *arg)
+{
+
+	switch (what) {
+	case MOD_LOAD:
+		smrs_init();
+		smrs_start();
+		break;
+	case MOD_UNLOAD:
+		smrs_fini();
+		break;
+	default:
+		break;
+	}
+	return (0);
+}
+
+moduledata_t smrs_meta = {
+	"smrstress",
+	smrs_modevent,
+	NULL
+};
+DECLARE_MODULE(smrstress, smrs_meta, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
+MODULE_VERSION(smrstress, 1);