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systemd/src/test/test-barrier.c
Daniel Mack b26fa1a2fb tree-wide: remove Emacs lines from all files 
This should be handled fine now by .dir-locals.el, so need to carry that
stuff in every file.
2016-02-10 13:41:57 +01:00

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/***
This file is part of systemd.
Copyright 2014 David Herrmann <dh.herrmann@gmail.com>
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
/*
* IPC barrier tests
* These tests verify the correct behavior of the IPC Barrier implementation.
* Note that the tests use alarm-timers to verify dead-locks and timeouts. These
* might not work on slow machines where 20ms are too short to perform specific
* operations (though, very unlikely). In case that turns out true, we have to
* increase it at the slightly cost of lengthen test-duration on other machines.
*/
#include <stdio.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <unistd.h>
#include "barrier.h"
#include "util.h"
/* 20ms to test deadlocks; All timings use multiples of this constant as
* alarm/sleep timers. If this timeout is too small for slow machines to perform
* the requested operations, we have to increase it. On an i7 this works fine
* with 1ms base-time, so 20ms should be just fine for everyone. */
#define BASE_TIME (20 * USEC_PER_MSEC)
static void set_alarm(usec_t usecs) {
struct itimerval v = { };
timeval_store(&v.it_value, usecs);
assert_se(setitimer(ITIMER_REAL, &v, NULL) >= 0);
}
static void sleep_for(usec_t usecs) {
/* stupid usleep() might fail if >1000000 */
assert_se(usecs < USEC_PER_SEC);
usleep(usecs);
}
#define TEST_BARRIER(_FUNCTION, _CHILD_CODE, _WAIT_CHILD, _PARENT_CODE, _WAIT_PARENT) \
static void _FUNCTION(void) { \
Barrier b = BARRIER_NULL; \
pid_t pid1, pid2; \
\
assert_se(barrier_create(&b) >= 0); \
assert_se(b.me > 0); \
assert_se(b.them > 0); \
assert_se(b.pipe[0] > 0); \
assert_se(b.pipe[1] > 0); \
\
pid1 = fork(); \
assert_se(pid1 >= 0); \
if (pid1 == 0) { \
barrier_set_role(&b, BARRIER_CHILD); \
{ _CHILD_CODE; } \
exit(42); \
} \
\
pid2 = fork(); \
assert_se(pid2 >= 0); \
if (pid2 == 0) { \
barrier_set_role(&b, BARRIER_PARENT); \
{ _PARENT_CODE; } \
exit(42); \
} \
\
barrier_destroy(&b); \
set_alarm(999999); \
{ _WAIT_CHILD; } \
{ _WAIT_PARENT; } \
set_alarm(0); \
}
#define TEST_BARRIER_WAIT_SUCCESS(_pid) \
({ \
int pidr, status; \
pidr = waitpid(_pid, &status, 0); \
assert_se(pidr == _pid); \
assert_se(WIFEXITED(status)); \
assert_se(WEXITSTATUS(status) == 42); \
})
#define TEST_BARRIER_WAIT_ALARM(_pid) \
({ \
int pidr, status; \
pidr = waitpid(_pid, &status, 0); \
assert_se(pidr == _pid); \
assert_se(WIFSIGNALED(status)); \
assert_se(WTERMSIG(status) == SIGALRM); \
})
/*
* Test basic sync points
* This places a barrier in both processes and waits synchronously for them.
* The timeout makes sure the sync works as expected. The sleep_for() on one side
* makes sure the exit of the parent does not overwrite previous barriers. Due
* to the sleep_for(), we know that the parent already exited, thus there's a
* pending HUP on the pipe. However, the barrier_sync() prefers reads on the
* eventfd, thus we can safely wait on the barrier.
*/
TEST_BARRIER(test_barrier_sync,
({
set_alarm(BASE_TIME * 10);
assert_se(barrier_place(&b));
sleep_for(BASE_TIME * 2);
assert_se(barrier_sync(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid1),
({
set_alarm(BASE_TIME * 10);
assert_se(barrier_place(&b));
assert_se(barrier_sync(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid2));
/*
* Test wait_next()
* This places a barrier in the parent and syncs on it. The child sleeps while
* the parent places the barrier and then waits for a barrier. The wait will
* succeed as the child hasn't read the parent's barrier, yet. The following
* barrier and sync synchronize the exit.
*/
TEST_BARRIER(test_barrier_wait_next,
({
sleep_for(BASE_TIME);
set_alarm(BASE_TIME * 10);
assert_se(barrier_wait_next(&b));
assert_se(barrier_place(&b));
assert_se(barrier_sync(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid1),
({
set_alarm(BASE_TIME * 4);
assert_se(barrier_place(&b));
assert_se(barrier_sync(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid2));
/*
* Test wait_next() multiple times
* This places two barriers in the parent and waits for the child to exit. The
* child sleeps 20ms so both barriers _should_ be in place. It then waits for
* the parent to place the next barrier twice. The first call will fetch both
* barriers and return. However, the second call will stall as the parent does
* not place a 3rd barrier (the sleep caught two barriers). wait_next() is does
* not look at barrier-links so this stall is expected. Thus this test times
* out.
*/
TEST_BARRIER(test_barrier_wait_next_twice,
({
sleep_for(BASE_TIME);
set_alarm(BASE_TIME);
assert_se(barrier_wait_next(&b));
assert_se(barrier_wait_next(&b));
assert_se(0);
}),
TEST_BARRIER_WAIT_ALARM(pid1),
({
set_alarm(BASE_TIME * 10);
assert_se(barrier_place(&b));
assert_se(barrier_place(&b));
sleep_for(BASE_TIME * 4);
}),
TEST_BARRIER_WAIT_SUCCESS(pid2));
/*
* Test wait_next() with local barriers
* This is the same as test_barrier_wait_next_twice, but places local barriers
* between both waits. This does not have any effect on the wait so it times out
* like the other test.
*/
TEST_BARRIER(test_barrier_wait_next_twice_local,
({
sleep_for(BASE_TIME);
set_alarm(BASE_TIME);
assert_se(barrier_wait_next(&b));
assert_se(barrier_place(&b));
assert_se(barrier_place(&b));
assert_se(barrier_wait_next(&b));
assert_se(0);
}),
TEST_BARRIER_WAIT_ALARM(pid1),
({
set_alarm(BASE_TIME * 10);
assert_se(barrier_place(&b));
assert_se(barrier_place(&b));
sleep_for(BASE_TIME * 4);
}),
TEST_BARRIER_WAIT_SUCCESS(pid2));
/*
* Test wait_next() with sync_next()
* This is again the same as test_barrier_wait_next_twice but uses a
* synced wait as the second wait. This works just fine because the local state
* has no barriers placed, therefore, the remote is always in sync.
*/
TEST_BARRIER(test_barrier_wait_next_twice_sync,
({
sleep_for(BASE_TIME);
set_alarm(BASE_TIME);
assert_se(barrier_wait_next(&b));
assert_se(barrier_sync_next(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid1),
({
set_alarm(BASE_TIME * 10);
assert_se(barrier_place(&b));
assert_se(barrier_place(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid2));
/*
* Test wait_next() with sync_next() and local barriers
* This is again the same as test_barrier_wait_next_twice_local but uses a
* synced wait as the second wait. This works just fine because the local state
* is in sync with the remote.
*/
TEST_BARRIER(test_barrier_wait_next_twice_local_sync,
({
sleep_for(BASE_TIME);
set_alarm(BASE_TIME);
assert_se(barrier_wait_next(&b));
assert_se(barrier_place(&b));
assert_se(barrier_place(&b));
assert_se(barrier_sync_next(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid1),
({
set_alarm(BASE_TIME * 10);
assert_se(barrier_place(&b));
assert_se(barrier_place(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid2));
/*
* Test sync_next() and sync()
* This tests sync_*() synchronizations and makes sure they work fine if the
* local state is behind the remote state.
*/
TEST_BARRIER(test_barrier_sync_next,
({
set_alarm(BASE_TIME * 10);
assert_se(barrier_sync_next(&b));
assert_se(barrier_sync(&b));
assert_se(barrier_place(&b));
assert_se(barrier_place(&b));
assert_se(barrier_sync_next(&b));
assert_se(barrier_sync_next(&b));
assert_se(barrier_sync(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid1),
({
set_alarm(BASE_TIME * 10);
sleep_for(BASE_TIME);
assert_se(barrier_place(&b));
assert_se(barrier_place(&b));
assert_se(barrier_sync(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid2));
/*
* Test sync_next() and sync() with local barriers
* This tests timeouts if sync_*() is used if local barriers are placed but the
* remote didn't place any.
*/
TEST_BARRIER(test_barrier_sync_next_local,
({
set_alarm(BASE_TIME);
assert_se(barrier_place(&b));
assert_se(barrier_sync_next(&b));
assert_se(0);
}),
TEST_BARRIER_WAIT_ALARM(pid1),
({
sleep_for(BASE_TIME * 2);
}),
TEST_BARRIER_WAIT_SUCCESS(pid2));
/*
* Test sync_next() and sync() with local barriers and abortion
* This is the same as test_barrier_sync_next_local but aborts the sync in the
* parent. Therefore, the sync_next() succeeds just fine due to the abortion.
*/
TEST_BARRIER(test_barrier_sync_next_local_abort,
({
set_alarm(BASE_TIME * 10);
assert_se(barrier_place(&b));
assert_se(!barrier_sync_next(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid1),
({
assert_se(barrier_abort(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid2));
/*
* Test matched wait_abortion()
* This runs wait_abortion() with remote abortion.
*/
TEST_BARRIER(test_barrier_wait_abortion,
({
set_alarm(BASE_TIME * 10);
assert_se(barrier_wait_abortion(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid1),
({
assert_se(barrier_abort(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid2));
/*
* Test unmatched wait_abortion()
* This runs wait_abortion() without any remote abortion going on. It thus must
* timeout.
*/
TEST_BARRIER(test_barrier_wait_abortion_unmatched,
({
set_alarm(BASE_TIME);
assert_se(barrier_wait_abortion(&b));
assert_se(0);
}),
TEST_BARRIER_WAIT_ALARM(pid1),
({
sleep_for(BASE_TIME * 2);
}),
TEST_BARRIER_WAIT_SUCCESS(pid2));
/*
* Test matched wait_abortion() with local abortion
* This runs wait_abortion() with local and remote abortion.
*/
TEST_BARRIER(test_barrier_wait_abortion_local,
({
set_alarm(BASE_TIME * 10);
assert_se(barrier_abort(&b));
assert_se(!barrier_wait_abortion(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid1),
({
assert_se(barrier_abort(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid2));
/*
* Test unmatched wait_abortion() with local abortion
* This runs wait_abortion() with only local abortion. This must time out.
*/
TEST_BARRIER(test_barrier_wait_abortion_local_unmatched,
({
set_alarm(BASE_TIME);
assert_se(barrier_abort(&b));
assert_se(!barrier_wait_abortion(&b));
assert_se(0);
}),
TEST_BARRIER_WAIT_ALARM(pid1),
({
sleep_for(BASE_TIME * 2);
}),
TEST_BARRIER_WAIT_SUCCESS(pid2));
/*
* Test child exit
* Place barrier and sync with the child. The child only exits()s, which should
* cause an implicit abortion and wake the parent.
*/
TEST_BARRIER(test_barrier_exit,
({
}),
TEST_BARRIER_WAIT_SUCCESS(pid1),
({
set_alarm(BASE_TIME * 10);
assert_se(barrier_place(&b));
assert_se(!barrier_sync(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid2));
/*
* Test child exit with sleep
* Same as test_barrier_exit but verifies the test really works due to the
* child-exit. We add a usleep() which triggers the alarm in the parent and
* causes the test to time out.
*/
TEST_BARRIER(test_barrier_no_exit,
({
sleep_for(BASE_TIME * 2);
}),
TEST_BARRIER_WAIT_SUCCESS(pid1),
({
set_alarm(BASE_TIME);
assert_se(barrier_place(&b));
assert_se(!barrier_sync(&b));
}),
TEST_BARRIER_WAIT_ALARM(pid2));
/*
* Test pending exit against sync
* The parent places a barrier *and* exits. The 20ms wait in the child
* guarantees both are pending. However, our logic prefers pending barriers over
* pending exit-abortions (unlike normal abortions), thus the wait_next() must
* succeed, same for the sync_next() as our local barrier-count is smaller than
* the remote. Once we place a barrier our count is equal, so the sync still
* succeeds. Only if we place one more barrier, we're ahead of the remote, thus
* we will fail due to HUP on the pipe.
*/
TEST_BARRIER(test_barrier_pending_exit,
({
set_alarm(BASE_TIME * 4);
sleep_for(BASE_TIME * 2);
assert_se(barrier_wait_next(&b));
assert_se(barrier_sync_next(&b));
assert_se(barrier_place(&b));
assert_se(barrier_sync_next(&b));
assert_se(barrier_place(&b));
assert_se(!barrier_sync_next(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid1),
({
assert_se(barrier_place(&b));
}),
TEST_BARRIER_WAIT_SUCCESS(pid2));
int main(int argc, char *argv[]) {
/*
* This test uses real-time alarms and sleeps to test for CPU races
* explicitly. This is highly fragile if your system is under load. We
* already increased the BASE_TIME value to make the tests more robust,
* but that just makes the test take significantly longer. Hence,
* disable the test by default, so it will not break CI.
*/
if (argc < 2)
return EXIT_TEST_SKIP;
log_parse_environment();
log_open();
test_barrier_sync();
test_barrier_wait_next();
test_barrier_wait_next_twice();
test_barrier_wait_next_twice_sync();
test_barrier_wait_next_twice_local();
test_barrier_wait_next_twice_local_sync();
test_barrier_sync_next();
test_barrier_sync_next_local();
test_barrier_sync_next_local_abort();
test_barrier_wait_abortion();
test_barrier_wait_abortion_unmatched();
test_barrier_wait_abortion_local();
test_barrier_wait_abortion_local_unmatched();
test_barrier_exit();
test_barrier_no_exit();
test_barrier_pending_exit();
return 0;
}
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