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authorDavid Edmondson <david.edmondson@oracle.com>2021-03-25 12:29:41 +0100
committerStefan Hajnoczi <stefanha@redhat.com>2021-03-31 10:44:21 +0100
commitb6489ac06695e257ea0a9841364577e247fdee30 (patch)
tree99a6e235d356604850385ff49cce3b68e5b90c01 /tests
parent25bc2daed0482732a2dd258dde4386f505582fa9 (diff)
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 | | | | | <queued> | | | | | | rdlock | | | | | <queued> | | | | | | wrlock | | | | | <queued> | | unlock | | | | | yield | | | | | | <dequeued> | | | | | downgrade | | | | | ... | | | | | unlock | | | | | | <dequeued> | | | | | <queued> | | 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 <david.edmondson@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 20210325112941.365238-7-pbonzini@redhat.com Message-Id: <20210309144015.557477-5-david.edmondson@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'tests')
-rw-r--r--tests/unit/test-coroutine.c99
1 files changed, 99 insertions, 0 deletions
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 | | |
+ * | | <queued> | | |
+ * | | | rdlock | |
+ * | | | <queued> | |
+ * | | | | wrlock |
+ * | | | | <queued> |
+ * | unlock | | | |
+ * | yield | | | |
+ * | | <dequeued> | | |
+ * | | downgrade | | |
+ * | | | <dequeued> | |
+ * | | | unlock | |
+ * | | ... | | |
+ * | | unlock | | |
+ * | | | | <dequeued> |
+ * | | | | 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);