From: Robert Sanford <rsanf...@akamai.com>
Add new timer-manage race-condition test: We wrote a test to confirm
our suspicion that we could crash rte_timer_manage() under the right
circumstances. We repeatedly set several timers to expire at roughly
the same time on the master core. The master lcore just delays and runs
rte_timer_manage() about ten times per second. The slave lcores all
watch the first timer (timer-0) to see when rte_timer_manage() is
running on the master, i.e., timer-0's state is not PENDING.
At this point, each slave attempts to reset a subset of the timers to
a later expiration time. The goal here is to have the slaves moving
most of the timers to a different place in the master's pending-list,
while the master is traversing the same next-pointers (the slaves'
sl_next[0] pointers) and running callback functions. This eventually
results in the master traversing a corrupted linked-list.
In our observations, it results in an infinite loop.
Signed-off-by: Robert Sanford <rsanford at akamai.com>
---
app/test/Makefile | 1 +
app/test/test_timer_racecond.c | 209 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 210 insertions(+), 0 deletions(-)
create mode 100644 app/test/test_timer_racecond.c
diff --git a/app/test/Makefile b/app/test/Makefile
index caa359c..e7f148f 100644
--- a/app/test/Makefile
+++ b/app/test/Makefile
@@ -71,6 +71,7 @@ SRCS-y += test_rwlock.c
SRCS-$(CONFIG_RTE_LIBRTE_TIMER) += test_timer.c
SRCS-$(CONFIG_RTE_LIBRTE_TIMER) += test_timer_perf.c
+SRCS-$(CONFIG_RTE_LIBRTE_TIMER) += test_timer_racecond.c
SRCS-y += test_mempool.c
SRCS-y += test_mempool_perf.c
diff --git a/app/test/test_timer_racecond.c b/app/test/test_timer_racecond.c
new file mode 100644
index 0000000..32693d8
--- /dev/null
+++ b/app/test/test_timer_racecond.c
@@ -0,0 +1,209 @@
+/*-
+ * BSD LICENSE
+ *
+ * Copyright(c) 2015 Akamai Technologies.
+ * 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.
+ * * Neither the name of Intel Corporation nor the names of its
+ * contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "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 COPYRIGHT
+ * OWNER OR CONTRIBUTORS 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 <stdio.h>
+#include <unistd.h>
+#include <inttypes.h>
+#include <rte_cycles.h>
+#include <rte_timer.h>
+#include <rte_common.h>
+#include <rte_lcore.h>
+#include <rte_random.h>
+#include <rte_malloc.h>
+
+#undef TEST_TIMER_RACECOND_VERBOSE
+
+#ifdef RTE_EXEC_ENV_LINUXAPP
+#define usec_delay(us) usleep(us)
+#else
+#define usec_delay(us) rte_delay_us(us)
+#endif
+
+#define BILLION (1UL << 30)
+
+#define TEST_DURATION_S 20 /* in seconds */
+#define N_TIMERS 50
+
+static struct rte_timer timer[N_TIMERS];
+static unsigned timer_lcore_id[N_TIMERS];
+
+static unsigned master;
+static volatile unsigned stop_slaves;
+
+static int reload_timer(struct rte_timer *tim);
+
+static void
+timer_cb(struct rte_timer *tim, void *arg __rte_unused)
+{
+ /* Simulate slow callback function, 100 us. */
+ rte_delay_us(100);
+
+#ifdef TEST_TIMER_RACECOND_VERBOSE
+ if (tim == &timer[0])
+ printf("------------------------------------------------\n");
+ printf("timer_cb: core %u timer %lu\n",
+ rte_lcore_id(), tim - timer);
+#endif
+ (void)reload_timer(tim);
+}
+
+RTE_DEFINE_PER_LCORE(unsigned, n_reset_collisions);
+
+static int
+reload_timer(struct rte_timer *tim)
+{
+ /* Make timer expire roughly when the TSC hits the next BILLION
+ * multiple. Add in timer's index to make them expire in nearly
+ * sorted order. This makes all timers somewhat synchronized,
+ * firing ~2-3 times per second, assuming 2-3 GHz TSCs.
+ */
+ uint64_t ticks = BILLION - (rte_get_timer_cycles() % BILLION) +
+ (tim - timer);
+ int ret;
+
+ ret = rte_timer_reset(tim, ticks, PERIODICAL, master, timer_cb, NULL);
+ if (ret != 0) {
+#ifdef TEST_TIMER_RACECOND_VERBOSE
+ printf("- core %u failed to reset timer %lu (OK)\n",
+ rte_lcore_id(), tim - timer);
+#endif
+ RTE_PER_LCORE(n_reset_collisions) += 1;
+ }
+ return ret;
+}
+
+static int
+slave_main_loop(__attribute__((unused)) void *arg)
+{
+ unsigned lcore_id = rte_lcore_id();
+ unsigned i;
+
+ RTE_PER_LCORE(n_reset_collisions) = 0;
+
+ printf("Starting main loop on core %u\n", lcore_id);
+
+ while (!stop_slaves) {
+ /* Wait until the timer manager is running.
+ * We know it's running when we see timer[0] NOT pending.
+ */
+ if (rte_timer_pending(&timer[0])) {
+ rte_pause();
+ continue;
+ }
+
+ /* Now, go cause some havoc!
+ * Reload our timers.
+ */
+ for (i = 0; i < N_TIMERS; i++) {
+ if (timer_lcore_id[i] == lcore_id)
+ (void)reload_timer(&timer[i]);
+ }
+ usec_delay(100*1000); /* sleep 100 ms */
+ }
+
+ if (RTE_PER_LCORE(n_reset_collisions) != 0) {
+ printf("- core %u, %u reset collisions (OK)\n",
+ lcore_id, RTE_PER_LCORE(n_reset_collisions));
+ }
+ return 0;
+}
+
+static int
+test_timer_racecond(void)
+{
+ int ret;
+ uint64_t hz;
+ uint64_t cur_time;
+ uint64_t end_time;
+ int64_t diff = 0;
+ unsigned lcore_id;
+ unsigned i;
+
+ master = lcore_id = rte_lcore_id();
+ hz = rte_get_timer_hz();
+
+ /* init and start timers */
+ for (i = 0; i < N_TIMERS; i++) {
+ rte_timer_init(&timer[i]);
+ ret = reload_timer(&timer[i]);
+ TEST_ASSERT(ret == 0, "reload_timer failed");
+
+ /* Distribute timers to slaves.
+ * Note that we assign timer[0] to the master.
+ */
+ timer_lcore_id[i] = lcore_id;
+ lcore_id = rte_get_next_lcore(lcore_id, 1, 1);
+ }
+
+ /* calculate the "end of test" time */
+ cur_time = rte_get_timer_cycles();
+ end_time = cur_time + (hz * TEST_DURATION_S);
+
+ /* start slave cores */
+ stop_slaves = 0;
+ printf("Start timer manage race condition test (%u seconds)\n",
+ TEST_DURATION_S);
+ rte_eal_mp_remote_launch(slave_main_loop, NULL, SKIP_MASTER);
+
+ while (diff >= 0) {
+ /* run the timers */
+ rte_timer_manage();
+
+ /* wait 100 ms */
+ usec_delay(100*1000);
+
+ cur_time = rte_get_timer_cycles();
+ diff = end_time - cur_time;
+ }
+
+ /* stop slave cores */
+ printf("Stopping timer manage race condition test\n");
+ stop_slaves = 1;
+ rte_eal_mp_wait_lcore();
+
+ /* stop timers */
+ for (i = 0; i < N_TIMERS; i++) {
+ ret = rte_timer_stop(&timer[i]);
+ TEST_ASSERT(ret == 0, "rte_timer_stop failed");
+ }
+
+ return TEST_SUCCESS;
+}
+
+static struct test_command timer_racecond_cmd = {
+ .command = "timer_racecond_autotest",
+ .callback = test_timer_racecond,
+};
+REGISTER_TEST_COMMAND(timer_racecond_cmd);
--
1.7.1
