Index: kernel/test/synch/rcu1.c
===================================================================
--- kernel/test/synch/rcu1.c	(revision 5b6c03370fd0afc552e341134e2e6161f611a180)
+++ kernel/test/synch/rcu1.c	(revision 5b6c03370fd0afc552e341134e2e6161f611a180)
@@ -0,0 +1,960 @@
+/*
+ * Copyright (c) 2012 Adam Hraska
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - 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.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * 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.
+ */
+
+#include <test.h>
+#include <arch.h>
+#include <atomic.h>
+#include <print.h>
+#include <proc/thread.h>
+#include <macros.h>
+
+#include <synch/rcu.h>
+
+#include "abi/errno.h"
+#include "time/delay.h"
+
+#define MAX_THREADS 32
+
+static int one_idx = 0;
+static thread_t *thread[MAX_THREADS] = {0};
+
+typedef struct {
+	rcu_item_t rcu;
+	bool exited;
+} exited_t;
+
+#define ERACE   123
+#define ECBLOST 432
+
+/*-------------------------------------------------------------------*/
+static void wait_for_cb_exit(size_t secs, exited_t *p, int *presult)
+{
+	size_t loops = 0;
+	/* 4 secs max */
+	size_t loop_ms_sec = 500;
+	size_t max_loops = ((secs * 1000 + loop_ms_sec - 1) / loop_ms_sec);
+
+	while (loops < max_loops && !p->exited) {
+		++loops;
+		thread_usleep(loop_ms_sec * 1000);
+		TPRINTF(".");
+	}
+	
+	if (!p->exited) {
+		*presult = ECBLOST;
+	}
+}
+
+static size_t get_thread_cnt(void)
+{
+	return min(MAX_THREADS, config.cpu_active * 4);
+}
+
+static void run_thread(size_t k, void (*func)(void*), void *arg)
+{
+	ASSERT(thread[k] == NULL);
+	
+	thread[k] = thread_create(func, arg, TASK, THREAD_FLAG_NONE, 
+		"test-rcu-thread");
+		
+	if(thread[k]) {
+		/* Try to distribute evenly but allow migration. */
+		thread[k]->cpu = &cpus[k % config.cpu_active];
+		thread_ready(thread[k]);
+	}
+}
+
+static void run_all(void (*func)(void*))
+{
+	size_t thread_cnt = get_thread_cnt();
+	
+	one_idx = 0;
+	
+	for (size_t i = 0; i < thread_cnt; ++i) {
+		run_thread(i, func, 0);
+	}
+}
+
+static void join_all(void)
+{
+	size_t thread_cnt = get_thread_cnt();
+	
+	one_idx = 0;
+	
+	for (size_t i = 0; i < thread_cnt; ++i) {
+		if (thread[i]) {
+			bool joined = false;
+			do {
+				int ret = thread_join_timeout(thread[i], 5 * 1000 * 1000, 0);
+				joined = (ret != ESYNCH_TIMEOUT);
+				
+				if (ret == ESYNCH_OK_BLOCKED) {
+					TPRINTF("%zu threads remain\n", thread_cnt - i - 1);
+				}
+			} while (!joined);
+			
+			thread_detach(thread[i]);
+			thread[i] = 0;
+		}
+	}
+}
+
+static void run_one(void (*func)(void*), void *arg)
+{
+	ASSERT(one_idx < MAX_THREADS);
+	run_thread(one_idx, func, arg);
+	++one_idx;
+}
+
+
+static void join_one(void)
+{
+	ASSERT(0 < one_idx && one_idx <= MAX_THREADS);
+
+	--one_idx;
+	
+	if (thread[one_idx]) {
+		thread_join(thread[one_idx]);
+		thread_detach(thread[one_idx]);
+		thread[one_idx] = 0;
+	}
+}
+
+/*-------------------------------------------------------------------*/
+
+
+static void nop_reader(void *arg)
+{
+	size_t nop_iters = (size_t)arg;
+	
+	TPRINTF("Enter nop-reader\n");
+	
+	for (size_t i = 0; i < nop_iters; ++i) {
+		rcu_read_lock();
+		rcu_read_unlock();
+	}
+	
+	TPRINTF("Exit nop-reader\n");
+}
+
+static void get_seq(size_t from, size_t to, size_t steps, size_t *seq)
+{
+	ASSERT(0 < steps && from <= to && 0 < to);
+	size_t inc = (to - from) / (steps - 1);
+	
+	for (size_t i = 0; i < steps - 1; ++i) {
+		seq[i] = i * inc + from;
+	}
+	
+	seq[steps - 1] = to;
+}
+
+static bool do_nop_readers(void)
+{
+	size_t seq[MAX_THREADS] = {0};
+	get_seq(100, 100000, get_thread_cnt(), seq);
+	
+	TPRINTF("\nRun %zu thr: repeat empty no-op reader sections\n", get_thread_cnt());
+	
+	for (size_t k = 0; k < get_thread_cnt(); ++k)
+		run_one(nop_reader, (void*)seq[k]);
+	
+	TPRINTF("\nJoining %zu no-op readers\n", get_thread_cnt());
+	join_all();
+	
+	return true;
+}
+
+/*-------------------------------------------------------------------*/
+
+
+
+static void long_reader(void *arg)
+{
+	const size_t iter_cnt = 100 * 1000 * 1000;
+	size_t nop_iters = (size_t)arg;
+	size_t outer_iters = iter_cnt / nop_iters;
+	
+	TPRINTF("Enter long-reader\n");
+	
+	for (size_t i = 0; i < outer_iters; ++i) {
+		rcu_read_lock();
+		
+		for (volatile size_t k = 0; k < nop_iters; ++k) {
+			// nop, but increment volatile k			
+		}
+		
+		rcu_read_unlock();
+	}
+	
+	TPRINTF("Exit long-reader\n");
+}
+
+static bool do_long_readers(void)
+{
+	size_t seq[MAX_THREADS] = {0};
+	get_seq(10, 1000 * 1000, get_thread_cnt(), seq);
+	
+	TPRINTF("\nRun %zu thr: repeat long reader sections, will preempt, no cbs.\n", 
+		get_thread_cnt());
+	
+	for (size_t k = 0; k < get_thread_cnt(); ++k)
+		run_one(long_reader, (void*)seq[k]);
+	
+	TPRINTF("\nJoining %zu readers with long reader sections.\n", get_thread_cnt());
+	join_all();
+	
+	return true;
+}
+
+/*-------------------------------------------------------------------*/
+
+
+static atomic_t nop_callbacks_cnt = {0};
+static const int nop_updater_iters = 10000;
+
+static void count_cb(rcu_item_t *item)
+{
+	atomic_inc(&nop_callbacks_cnt);
+	free(item);
+}
+
+static void nop_updater(void *arg)
+{
+	for (int i = 0; i < nop_updater_iters; ++i){
+		rcu_item_t *a = malloc(sizeof(rcu_item_t), 0);
+		rcu_item_t *b = malloc(sizeof(rcu_item_t), 0);
+		
+		if (a && b) {
+			rcu_call(a, count_cb);
+			rcu_call(b, count_cb);
+		} else {
+			free(a);
+			free(b);
+		}
+	}
+}
+
+static bool do_nop_callbacks(void)
+{
+	atomic_set(&nop_callbacks_cnt, 0);
+	
+	TPRINTF("\nRun %zu thr: post many no-op callbacks, no readers.\n", 
+		get_thread_cnt());
+	
+	run_all(nop_updater);
+	TPRINTF("\nJoining %zu no-op callback threads\n", get_thread_cnt());
+	join_all();
+	
+	size_t loop_cnt = 0, max_loops = 15;
+	size_t exp_cnt = 2 * nop_updater_iters * get_thread_cnt();
+
+	while (exp_cnt != atomic_get(&nop_callbacks_cnt) && loop_cnt < max_loops) {
+		++loop_cnt;
+		TPRINTF(".");
+		thread_sleep(1);
+	}
+	
+	return loop_cnt < max_loops;
+}
+
+/*-------------------------------------------------------------------*/
+
+typedef struct {
+	rcu_item_t rcu_item;
+	int cookie;
+} item_w_cookie_t;
+
+const int magic_cookie = 0x01234567;
+static int one_cb_is_done = 0;
+
+static void one_cb_done(rcu_item_t *item)
+{
+	ASSERT( ((item_w_cookie_t *)item)->cookie == magic_cookie);
+	one_cb_is_done = 1;
+	TPRINTF("Callback()\n");
+	free(item);
+}
+
+static void one_cb_reader(void *arg)
+{
+	TPRINTF("Enter one-cb-reader\n");
+	
+	rcu_read_lock();
+	
+	item_w_cookie_t *item = malloc(sizeof(item_w_cookie_t), 0);
+	item->cookie = magic_cookie;
+	
+	rcu_call(&item->rcu_item, one_cb_done);
+	
+	thread_sleep(1);
+	
+	rcu_read_unlock();
+	
+	TPRINTF("Exit one-cb-reader\n");
+}
+
+static bool do_one_cb(void)
+{
+	one_cb_is_done = 0;
+	
+	TPRINTF("\nRun a single reader that posts one callback.\n");
+	run_one(one_cb_reader, 0);
+	join_one();
+	
+	TPRINTF("\nJoined one-cb reader, wait for cb.\n");
+	size_t loop_cnt = 0;
+	size_t max_loops = 4;
+	
+	while (!one_cb_is_done && loop_cnt < max_loops) {
+		thread_usleep(50 * 1000);
+		++loop_cnt;
+	}
+	
+	return one_cb_is_done;
+}
+
+/*-------------------------------------------------------------------*/
+
+typedef struct {
+	size_t update_cnt;
+	size_t read_cnt;
+	size_t iters;
+} seq_work_t;
+
+typedef struct {
+	rcu_item_t rcu;
+	atomic_count_t start_time;
+} seq_item_t;
+
+
+static int seq_test_result = EOK;
+
+static atomic_t cur_time = {1};
+static atomic_count_t max_upd_done_time = {0};
+
+static void seq_cb(rcu_item_t *rcu_item)
+{
+	seq_item_t *item = member_to_inst(rcu_item, seq_item_t, rcu);
+	
+	/* Racy but errs to the conservative side, so it is ok. */
+	if (max_upd_done_time < item->start_time) {
+		max_upd_done_time = item->start_time;
+		
+		/* Make updated time visible */
+		memory_barrier();
+	}
+
+	free(item);
+}
+
+static void seq_func(void *arg)
+{
+	seq_work_t *work = (seq_work_t*)arg;
+	
+	/* Alternate between reader and updater roles. */
+	for (size_t k = 0; k < work->iters; ++k) {
+		/* Reader */
+		for (size_t i = 0; i < work->read_cnt; ++i) {
+			rcu_read_lock();
+			atomic_count_t start_time = atomic_postinc(&cur_time);
+			
+			for (volatile size_t d = 0; d < 10*i; ++d ){
+				/* no-op */
+			}
+			
+			/* Get most recent max_upd_done_time. */
+			memory_barrier();
+			
+			if (start_time < max_upd_done_time) {
+				seq_test_result = ERACE;
+			}
+			
+			rcu_read_unlock();
+			
+			if (seq_test_result != EOK) 
+				return;
+		}
+		
+		/* Updater */
+		for (size_t i = 0; i < work->update_cnt; i += 2) {
+			seq_item_t *a = malloc(sizeof(seq_item_t), 0);
+			seq_item_t *b = malloc(sizeof(seq_item_t), 0);
+			
+			if (a && b) {
+				a->start_time = atomic_postinc(&cur_time);
+				rcu_call(&a->rcu, seq_cb);
+				
+				b->start_time = atomic_postinc(&cur_time);
+				rcu_call(&b->rcu, seq_cb);
+			} else {
+				/* can leak a bit of mem */
+				TPRINTF("\n[out-of-mem]\n");
+				seq_test_result = ENOMEM;
+				return;
+			}
+		}
+		
+	} 
+}
+
+static bool do_seq_check(void)
+{
+	seq_test_result = EOK;
+	max_upd_done_time = 0;
+	atomic_set(&cur_time, 1);
+
+	const size_t iters = 100;
+	const size_t total_cnt = 1000;
+	size_t read_cnt[MAX_THREADS] = {0};
+	seq_work_t item[MAX_THREADS];
+	
+	get_seq(0, total_cnt, get_thread_cnt(), read_cnt);
+	
+	for (size_t i = 0; i < get_thread_cnt(); ++i) {
+		item[i].update_cnt = total_cnt - read_cnt[i];
+		item[i].read_cnt = read_cnt[i];
+		item[i].iters = iters;
+	}
+	
+	TPRINTF("\nRun %zu th: check callback completion time in readers. ~%zu cbs/"
+		"thread. Be patient.\n", get_thread_cnt(),	iters * total_cnt * 2);
+	
+	for (size_t i = 0; i < get_thread_cnt(); ++i) {
+		run_one(seq_func, &item[i]);
+	}
+	
+	TPRINTF("\nJoining %zu seq-threads\n", get_thread_cnt());
+	join_all();
+	
+	if (seq_test_result == ENOMEM) {
+		TPRINTF("\nErr: out-of mem\n");
+	} else if (seq_test_result == ERACE) {
+		TPRINTF("\nERROR: race detected!!\n");
+	} 
+	
+	return seq_test_result == EOK;
+}
+
+/*-------------------------------------------------------------------*/
+
+
+static void reader_unlocked(rcu_item_t *item)
+{
+	exited_t *p = (exited_t*)item;
+	p->exited = true;
+}
+
+static void reader_exit(void *arg)
+{
+	rcu_read_lock();
+	rcu_read_lock();
+	rcu_read_lock();
+	rcu_read_unlock();
+	
+	rcu_call((rcu_item_t*)arg, reader_unlocked);
+	
+	rcu_read_lock();
+	rcu_read_lock();
+	
+	/* Exit without unlocking the rcu reader section. */
+}
+
+static bool do_reader_exit(void)
+{
+	TPRINTF("\nReader exits thread with rcu_lock\n");
+	
+	exited_t *p = malloc(sizeof(exited_t), 0);
+	p->exited = false;
+	
+	run_one(reader_exit, p);	
+	join_one();
+	
+	int result = EOK;
+	wait_for_cb_exit(2, p, &result);
+	
+	if (result != EOK) {
+		TPRINTF("Err: RCU locked up after exiting from within a reader\n");
+		/* Leak the mem. */
+	} else {
+		free(p);
+	}
+	
+	return result == EOK;
+}
+
+/*-------------------------------------------------------------------*/
+
+/*-------------------------------------------------------------------*/
+
+typedef struct preempt_struct {
+	exited_t e;
+	int result;
+} preempt_t;
+
+
+static void preempted_unlocked(rcu_item_t *item)
+{
+	preempt_t *p = member_to_inst(item, preempt_t, e.rcu);
+	p->e.exited = true;
+	TPRINTF("Callback().\n");
+}
+
+static void preempted_reader_prev(void *arg)
+{
+	preempt_t *p = (preempt_t*)arg;
+	ASSERT(!p->e.exited);
+
+	TPRINTF("reader_prev{ ");
+	
+	rcu_read_lock();
+	scheduler();
+	rcu_read_unlock();
+
+	/* 
+	 * Start GP after exiting reader section w/ preemption. 
+	 * Just check that the callback does not lock up and is not lost.
+	 */
+	rcu_call(&p->e.rcu, preempted_unlocked);
+
+	TPRINTF("}reader_prev\n");
+}
+
+static void preempted_reader_inside_cur(void *arg)
+{
+	preempt_t *p = (preempt_t*)arg;
+	ASSERT(!p->e.exited);
+	
+	TPRINTF("reader_inside_cur{ ");
+	/* 
+	 * Start a GP and try to finish the reader before 
+	 * the GP ends (including preemption). 
+	 */
+	rcu_call(&p->e.rcu, preempted_unlocked);
+
+	/* Give RCU threads a chance to start up. */
+	scheduler();
+	scheduler();
+
+	rcu_read_lock();
+	/* Come back as soon as possible to complete before GP ends. */
+	thread_usleep(2);
+	rcu_read_unlock();
+
+	TPRINTF("}reader_inside_cur\n");
+}
+
+
+static void preempted_reader_cur(void *arg)
+{
+	preempt_t *p = (preempt_t*)arg;
+	ASSERT(!p->e.exited);
+	
+	TPRINTF("reader_cur{ ");
+	rcu_read_lock();
+
+	/* Start GP. */
+	rcu_call(&p->e.rcu, preempted_unlocked);
+
+	/* Preempt while cur GP detection is running */
+	thread_sleep(1);
+	
+	/* Err: exited before this reader completed. */
+	if (p->e.exited)
+		p->result = ERACE;
+
+	rcu_read_unlock();
+	TPRINTF("}reader_cur\n");
+}
+
+static void preempted_reader_next1(void *arg)
+{
+	preempt_t *p = (preempt_t*)arg;
+	ASSERT(!p->e.exited);
+	
+	TPRINTF("reader_next1{ ");
+	rcu_read_lock();
+
+	/* Preempt before cur GP detection starts. */
+	scheduler();
+	
+	/* Start GP. */
+	rcu_call(&p->e.rcu, preempted_unlocked);
+
+	/* Err: exited before this reader completed. */
+	if (p->e.exited)
+		p->result = ERACE;
+
+	rcu_read_unlock();
+	TPRINTF("}reader_next1\n");
+}
+
+static void preempted_reader_next2(void *arg)
+{
+	preempt_t *p = (preempt_t*)arg;
+	ASSERT(!p->e.exited);
+	
+	TPRINTF("reader_next2{ ");
+	rcu_read_lock();
+
+	/* Preempt before cur GP detection starts. */
+	scheduler();
+	
+	/* Start GP. */
+	rcu_call(&p->e.rcu, preempted_unlocked);
+
+	/* 
+	 * Preempt twice while GP is running after we've been known 
+	 * to hold up the GP just to make sure multiple preemptions
+	 * are properly tracked if a reader is delaying the cur GP.
+	 */
+	thread_sleep(1);
+	thread_sleep(1);
+
+	/* Err: exited before this reader completed. */
+	if (p->e.exited)
+		p->result = ERACE;
+
+	rcu_read_unlock();
+	TPRINTF("}reader_next2\n");
+}
+
+
+static bool do_one_reader_preempt(void (*f)(void*), const char *err)
+{
+	preempt_t *p = malloc(sizeof(preempt_t), 0);
+	ASSERT(p);
+	p->e.exited = false;
+	p->result = EOK;
+	
+	run_one(f, p);	
+	join_one();
+	
+	wait_for_cb_exit(4, &p->e, &p->result);
+	
+	if (p->result == EOK) {
+		free(p);
+		return true;
+	} else {
+		TPRINTF(err);
+		/* Leak a bit of mem. */
+		return false;
+	}
+}
+
+static bool do_reader_preempt(void)
+{
+	TPRINTF("\nReader preempts; after GP start, before GP, twice before GP\n");
+	
+	bool success = true;
+	bool ok = true;
+	
+	ok = do_one_reader_preempt(preempted_reader_prev, 
+		"Err: preempted_reader_prev()\n");
+	success = success && ok;
+	
+	ok = do_one_reader_preempt(preempted_reader_inside_cur, 
+		"Err: preempted_reader_inside_cur()\n");
+	success = success && ok;
+	
+	ok = do_one_reader_preempt(preempted_reader_cur, 
+		"Err: preempted_reader_cur()\n");
+	success = success && ok;
+	
+	ok = do_one_reader_preempt(preempted_reader_next1, 
+		"Err: preempted_reader_next1()\n");
+	success = success && ok;
+
+	ok = do_one_reader_preempt(preempted_reader_next2, 
+		"Err: preempted_reader_next2()\n");
+	success = success && ok;
+	
+	return success;
+}
+
+/*-------------------------------------------------------------------*/
+typedef struct {
+	bool reader_done;
+	bool reader_running;
+	bool synch_running;
+} synch_t;
+
+static void synch_reader(void *arg)
+{
+	synch_t *synch = (synch_t *) arg;
+	
+	rcu_read_lock();
+
+	/* Contain synch accessing after reader section beginning. */
+	memory_barrier();
+	
+	synch->reader_running = true;
+	
+	while (!synch->synch_running) {
+		/* 0.5 sec*/
+		delay(500 * 1000);
+	}
+	
+	/* Run for 1 sec */
+	delay(1000 * 1000);
+	/* thread_join() propagates done to do_synch() */
+	synch->reader_done = true;
+	
+	rcu_read_unlock();
+}
+
+
+static bool do_synch(void)
+{
+	TPRINTF("\nSynchronize with long reader\n");
+	
+	synch_t *synch = malloc(sizeof(synch_t), 0);
+	
+	if (!synch) {
+		return false;
+	}
+	
+	synch->reader_done = false;
+	synch->reader_running = false;
+	synch->synch_running = false;
+	
+	run_one(synch_reader, synch);	
+	
+	/* Wait for the reader to enter its critical section. */
+	scheduler();
+	while (!synch->reader_running) {
+		thread_usleep(500 * 1000);
+	}
+	
+	synch->synch_running = true;
+	
+	rcu_synchronize();
+	join_one();
+	
+	
+	if (synch->reader_done) {
+		free(synch);
+		return true;
+	} else {
+		TPRINTF("Err: synchronize() exited prematurely \n");
+		/* Leak some mem. */
+		return false;
+	}
+}
+
+/*-------------------------------------------------------------------*/
+
+typedef struct {
+	size_t iters;
+	bool master;
+} stress_t;
+
+
+static void stress_reader(void *arg)
+{
+	bool *done = (bool*) arg;
+	
+	while (!*done) {
+		rcu_read_lock();
+		rcu_read_unlock();
+		
+		/* 
+		 * Do some work outside of the reader section so we are not always
+		 * preempted in the reader section.
+		 */
+		delay(5);
+	}
+}
+
+static void stress_cb(rcu_item_t *item)
+{
+	/* 5 us * 1000 * 1000 iters == 5 sec per updater thread */
+	delay(5);
+}
+
+static void stress_updater(void *arg)
+{
+	stress_t *s = (stress_t *)arg;
+	
+	for (size_t i = 0; i < s->iters; ++i) {
+		rcu_item_t *item = malloc(sizeof(rcu_item_t), 0);
+		
+		if (item)
+			rcu_call(item, stress_cb);
+		
+		if (s->master && 0 == (i % (s->iters/100 + 1)))
+			TPRINTF(".");
+	}
+}
+
+static bool do_stress(void)
+{
+	//size_t cb_per_thread = 1000 * 1000;
+	size_t cb_per_thread = 1000 * 1000;
+	bool done = false;
+	stress_t master = { .iters = cb_per_thread, .master = true }; 
+	stress_t worker = { .iters = cb_per_thread, .master = false }; 
+	
+	size_t thread_cnt = min(MAX_THREADS, config.cpu_active);
+	/* Each cpu has one reader and one updater. */
+	size_t reader_cnt = thread_cnt;
+	size_t updater_cnt = thread_cnt;
+
+	TPRINTF("\nStress: Run %zu nop-readers and %zu updaters. %zu cbs/updater. "
+		"Be very patient.\n", reader_cnt, updater_cnt, cb_per_thread);
+	
+	for (size_t k = 0; k < reader_cnt; ++k) {
+		run_one(stress_reader, &done);
+	}
+
+	for (size_t k = 0; k < updater_cnt; ++k) {
+		run_one(stress_updater, k > 0 ? &worker : &master);
+	}
+	
+	TPRINTF("\nJoining %zu stress updaters.\n", updater_cnt);
+	
+	for (size_t k = 0; k < updater_cnt; ++k) {
+		join_one();
+	}
+	
+	done = true;
+
+	TPRINTF("\nJoining %zu stress nop-readers.\n", reader_cnt);
+	
+	join_all();
+	return true;
+}
+/*-------------------------------------------------------------------*/
+
+typedef struct {
+	rcu_item_t r;
+	size_t total_cnt;
+	size_t count_down;
+	bool expedite;
+} expedite_t;
+
+static void expedite_cb(rcu_item_t *arg)
+{
+	expedite_t *e = (expedite_t *)arg;
+	
+	if (1 < e->count_down) {
+		--e->count_down;
+		
+		if (0 == (e->count_down % (e->total_cnt/100 + 1))) {
+			TPRINTF("*");
+		}
+		
+		_rcu_call(e->expedite, &e->r, expedite_cb);
+	} else {
+		memory_barrier();
+		e->count_down = 0;
+	}
+}
+
+static void run_expedite(bool exp, size_t cnt)
+{
+	expedite_t e;
+	e.total_cnt = cnt;
+	e.count_down = cnt;
+	e.expedite = exp;
+	
+	_rcu_call(e.expedite, &e.r, expedite_cb);
+	
+	while (0 < e.count_down) {
+		thread_sleep(1);
+		TPRINTF(".");
+	}
+}
+
+static bool do_expedite(void)
+{
+	size_t exp_cnt = 1000 * 1000;
+	size_t normal_cnt = 1 * 1000;
+	
+	TPRINTF("Expedited: sequence of %zu rcu_calls\n", exp_cnt);
+	run_expedite(true, exp_cnt);
+	TPRINTF("Normal/non-expedited: sequence of %zu rcu_calls\n", normal_cnt);
+	run_expedite(false, normal_cnt);
+	return true;
+}
+/*-------------------------------------------------------------------*/
+
+struct test_func {
+	bool include;
+	bool (*func)(void);
+	const char *desc;
+};
+
+
+const char *test_rcu1(void)
+{
+	struct test_func test_func[] = {
+		{ 1, do_one_cb, "do_one_cb" },
+		{ 1, do_reader_preempt, "do_reader_preempt" },
+		{ 1, do_synch, "do_synch" },
+		{ 1, do_reader_exit, "do_reader_exit" },
+		{ 1, do_nop_readers, "do_nop_readers" },
+		{ 1, do_seq_check, "do_seq_check" },
+		{ 0, do_long_readers, "do_long_readers" },
+		{ 1, do_nop_callbacks, "do_nop_callbacks" },
+		{ 0, do_expedite, "do_expedite" },
+		{ 1, do_stress, "do_stress" },
+		{ 0, 0, 0 }
+	};
+	
+	bool success = true;
+	bool ok = true;
+	uint64_t completed_gps = rcu_completed_gps();
+	uint64_t delta_gps = 0;
+	
+	for (int i = 0; test_func[i].func != 0; ++i) {
+		if (!test_func[i].include) {
+			TPRINTF("\nSubtest %s() skipped.\n", test_func[i].desc);
+			continue;
+		}
+		
+		ok = test_func[i].func();
+		success = success && ok;
+		
+		delta_gps = rcu_completed_gps() - completed_gps;
+		completed_gps += delta_gps;
+
+		if (ok) {  
+			TPRINTF("\nSubtest %s() ok (GPs: %" PRIu64 ").\n", 
+				test_func[i].desc, delta_gps);
+		} else {
+			TPRINTF("\nFailed: %s(). Pausing for 5 secs.\n", test_func[i].desc);
+			thread_sleep(5);
+		} 
+	}
+
+	if (success)
+		return 0;
+	else
+		return "One of the tests failed.";
+}
Index: kernel/test/synch/rcu1.def
===================================================================
--- kernel/test/synch/rcu1.def	(revision 5b6c03370fd0afc552e341134e2e6161f611a180)
+++ kernel/test/synch/rcu1.def	(revision 5b6c03370fd0afc552e341134e2e6161f611a180)
@@ -0,0 +1,6 @@
+{
+	"rcu1",
+	"Basic RCU test",
+	&test_rcu1,
+	true
+},
Index: kernel/test/test.c
===================================================================
--- kernel/test/test.c	(revision 0d567128e8779f20e00b0f9912a328a8bfdaf195)
+++ kernel/test/test.c	(revision 5b6c03370fd0afc552e341134e2e6161f611a180)
@@ -50,4 +50,5 @@
 #include <synch/semaphore1.def>
 #include <synch/semaphore2.def>
+#include <synch/rcu1.def>
 #include <synch/workqueue1.def>
 #include <synch/workqueue2.def>
Index: kernel/test/test.h
===================================================================
--- kernel/test/test.h	(revision 0d567128e8779f20e00b0f9912a328a8bfdaf195)
+++ kernel/test/test.h	(revision 5b6c03370fd0afc552e341134e2e6161f611a180)
@@ -81,4 +81,5 @@
 extern const char *test_workqueue3(void);
 extern const char *test_workqueue3quit(void);
+extern const char *test_rcu1(void);