From b6489ac06695e257ea0a9841364577e247fdee30 Mon Sep 17 00:00:00 2001 From: David Edmondson Date: Thu, 25 Mar 2021 12:29:41 +0100 Subject: [PATCH] test-coroutine: Add rwlock downgrade test Test that downgrading an rwlock does not result in a failure to schedule coroutines queued on the rwlock. The diagram associated with test_co_rwlock_downgrade() describes the intended behaviour, but what was observed previously corresponds to: | c1 | c2 | c3 | c4 | |--------+------------+------------+----------| | rdlock | | | | | yield | | | | | | wrlock | | | | | | | | | | | rdlock | | | | | | | | | | | wrlock | | | | | | | unlock | | | | | yield | | | | | | | | | | | downgrade | | | | | ... | | | | | unlock | | | | | | | | | | | | | This results in a failure... ERROR:../tests/test-coroutine.c:369:test_co_rwlock_downgrade: assertion failed: (c3_done) Bail out! ERROR:../tests/test-coroutine.c:369:test_co_rwlock_downgrade: assertion failed: (c3_done) ...as a result of the c3 coroutine failing to run to completion. Signed-off-by: David Edmondson Signed-off-by: Paolo Bonzini Message-id: 20210325112941.365238-7-pbonzini@redhat.com Message-Id: <20210309144015.557477-5-david.edmondson@oracle.com> Signed-off-by: Paolo Bonzini Signed-off-by: Stefan Hajnoczi --- tests/unit/test-coroutine.c | 99 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 99 insertions(+) diff --git a/tests/unit/test-coroutine.c b/tests/unit/test-coroutine.c index 6e6f51d480..aa77a3bcb3 100644 --- a/tests/unit/test-coroutine.c +++ b/tests/unit/test-coroutine.c @@ -325,6 +325,104 @@ static void test_co_rwlock_upgrade(void) g_assert(c2_done); } +static void coroutine_fn rwlock_rdlock_yield(void *opaque) +{ + qemu_co_rwlock_rdlock(&rwlock); + qemu_coroutine_yield(); + + qemu_co_rwlock_unlock(&rwlock); + qemu_coroutine_yield(); + + *(bool *)opaque = true; +} + +static void coroutine_fn rwlock_wrlock_downgrade(void *opaque) +{ + qemu_co_rwlock_wrlock(&rwlock); + + qemu_co_rwlock_downgrade(&rwlock); + qemu_co_rwlock_unlock(&rwlock); + *(bool *)opaque = true; +} + +static void coroutine_fn rwlock_rdlock(void *opaque) +{ + qemu_co_rwlock_rdlock(&rwlock); + + qemu_co_rwlock_unlock(&rwlock); + *(bool *)opaque = true; +} + +static void coroutine_fn rwlock_wrlock(void *opaque) +{ + qemu_co_rwlock_wrlock(&rwlock); + + qemu_co_rwlock_unlock(&rwlock); + *(bool *)opaque = true; +} + +/* + * Check that downgrading a reader-writer lock does not cause a hang. + * + * Four coroutines are used to produce a situation where there are + * both reader and writer hopefuls waiting to acquire an rwlock that + * is held by a reader. + * + * The correct sequence of operations we aim to provoke can be + * represented as: + * + * | c1 | c2 | c3 | c4 | + * |--------+------------+------------+------------| + * | rdlock | | | | + * | yield | | | | + * | | wrlock | | | + * | | | | | + * | | | rdlock | | + * | | | | | + * | | | | wrlock | + * | | | | | + * | unlock | | | | + * | yield | | | | + * | | | | | + * | | downgrade | | | + * | | | | | + * | | | unlock | | + * | | ... | | | + * | | unlock | | | + * | | | | | + * | | | | unlock | + */ +static void test_co_rwlock_downgrade(void) +{ + bool c1_done = false; + bool c2_done = false; + bool c3_done = false; + bool c4_done = false; + Coroutine *c1, *c2, *c3, *c4; + + qemu_co_rwlock_init(&rwlock); + + c1 = qemu_coroutine_create(rwlock_rdlock_yield, &c1_done); + c2 = qemu_coroutine_create(rwlock_wrlock_downgrade, &c2_done); + c3 = qemu_coroutine_create(rwlock_rdlock, &c3_done); + c4 = qemu_coroutine_create(rwlock_wrlock, &c4_done); + + qemu_coroutine_enter(c1); + qemu_coroutine_enter(c2); + qemu_coroutine_enter(c3); + qemu_coroutine_enter(c4); + + qemu_coroutine_enter(c1); + + g_assert(c2_done); + g_assert(c3_done); + g_assert(c4_done); + + qemu_coroutine_enter(c1); + + g_assert(c1_done); +} + /* * Check that creation, enter, and return work */ @@ -563,6 +661,7 @@ int main(int argc, char **argv) g_test_add_func("/locking/co-mutex", test_co_mutex); g_test_add_func("/locking/co-mutex/lockable", test_co_mutex_lockable); g_test_add_func("/locking/co-rwlock/upgrade", test_co_rwlock_upgrade); + g_test_add_func("/locking/co-rwlock/downgrade", test_co_rwlock_downgrade); if (g_test_perf()) { g_test_add_func("/perf/lifecycle", perf_lifecycle); g_test_add_func("/perf/nesting", perf_nesting); -- 2.11.4.GIT