Add 2 tests: test_main_and_then_iothread_drain ensures that if the main thread drains, the iothread cannot drain (and thus read the graph). test_main_and_iothread_drain instead lets main loop and iothread to drain together, and makes sure that no drain happens in parallel.
Note that we are using bdrv_subtree_drained_{begin/end}_unlocked to try avoid using the aiocontext lock as much as possible, since it will eventually go away. Signed-off-by: Emanuele Giuseppe Esposito <eespo...@redhat.com> --- tests/unit/test-bdrv-drain.c | 218 +++++++++++++++++++++++++++++++++++ 1 file changed, 218 insertions(+) diff --git a/tests/unit/test-bdrv-drain.c b/tests/unit/test-bdrv-drain.c index 36be84ae55..bf7fdcb568 100644 --- a/tests/unit/test-bdrv-drain.c +++ b/tests/unit/test-bdrv-drain.c @@ -1534,6 +1534,219 @@ static void test_set_aio_context(void) iothread_join(b); } +typedef struct ParallelDrainJob { + BlockJob common; + BlockBackend *blk; + BlockDriverState *bs; + IOThread *a; + bool should_fail; + bool allowed_to_run; + bool conclude_test; + bool job_started; +} ParallelDrainJob; + +typedef struct BDRVParallelTestState { + ParallelDrainJob *job; +} BDRVParallelTestState; + +static void coroutine_fn bdrv_test_par_co_drain(BlockDriverState *bs) +{ + BDRVParallelTestState *s = bs->opaque; + ParallelDrainJob *job = s->job; + assert(!qatomic_read(&job->should_fail)); +} + +static int parallel_run_test(Job *job, Error **errp) +{ + ParallelDrainJob *s = container_of(job, ParallelDrainJob, common.job); + s->job_started = true; + + while (!s->conclude_test) { + if (s->allowed_to_run) { + bdrv_subtree_drained_begin_unlocked(s->bs); + bdrv_subtree_drained_end_unlocked(s->bs); + } + job_pause_point(&s->common.job); + } + s->job_started = false; + + return 0; +} + +static BlockDriver bdrv_test_parallel = { + .format_name = "test", + .instance_size = sizeof(BDRVParallelTestState), + .supports_backing = true, + + .bdrv_co_drain_begin = bdrv_test_par_co_drain, + .bdrv_co_drain_end = bdrv_test_par_co_drain, + + .bdrv_child_perm = bdrv_default_perms, +}; + +static bool parallel_drained_poll(BlockJob *job) +{ + /* need to return false otherwise a drain in coroutine deadlocks */ + return false; +} + +static const BlockJobDriver test_block_job_driver_parallel = { + .job_driver = { + .instance_size = sizeof(ParallelDrainJob), + .run = parallel_run_test, + .user_resume = block_job_user_resume, + .free = block_job_free, + }, + .drained_poll = parallel_drained_poll, +}; + +static ParallelDrainJob *setup_job_test(void) +{ + BlockBackend *blk; + BlockDriverState *bs; + Error *err = NULL; + IOThread *a = iothread_new(); + AioContext *ctx_a = iothread_get_aio_context(a); + ParallelDrainJob *s; + BDRVParallelTestState *p; + int ret; + + blk = blk_new(qemu_get_aio_context(), + BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL); + blk_set_allow_aio_context_change(blk, true); + + bs = bdrv_new_open_driver(&bdrv_test_parallel, "parent", 0, + &error_abort); + p = bs->opaque; + + ret = blk_insert_bs(blk, bs, &error_abort); + assert(ret == 0); + + s = block_job_create("job1", &test_block_job_driver_parallel, + NULL, blk_bs(blk), 0, BLK_PERM_ALL, 0, JOB_DEFAULT, + NULL, NULL, &err); + s->bs = bs; + s->a = a; + s->blk = blk; + p->job = s; + + ret = bdrv_try_set_aio_context(bs, ctx_a, &error_abort); + assert(ret == 0); + assert(blk_get_aio_context(blk) == ctx_a); + assert(s->common.job.aio_context == ctx_a); + + return s; +} + +static void stop_and_tear_down_test(ParallelDrainJob *s) +{ + AioContext *ctx = iothread_get_aio_context(s->a); + + /* stop iothread */ + s->conclude_test = true; + + /* wait that it's stopped */ + while (s->job_started) { + aio_poll(qemu_get_current_aio_context(), false); + } + + aio_context_acquire(ctx); + bdrv_unref(s->bs); + blk_unref(s->blk); + aio_context_release(ctx); + iothread_join(s->a); +} + +/** + * test_main_and_then_iothread_drain: test that if the main + * loop drains, iothread cannot possibly drain. + * + * In this test, make sure that the main loop has firstly + * drained, and then allow the iothread to try and drain. + * + * Therefore, if the main loop drains, there is no way that + * the graph can be read or written by the iothread. + */ +static void test_main_and_then_iothread_drain(void) +{ + ParallelDrainJob *s = setup_job_test(); + + s->allowed_to_run = false; + job_start(&s->common.job); + + /* + * Wait that the iothread starts, even though it just + * loops without doing anything (allowed_to_run is false) + */ + while (!s->job_started) { + aio_poll(qemu_get_current_aio_context(), false); + } + + /* + * Drain in the main loop and ensure that no drain + * is performed by the iothread. + */ + bdrv_subtree_drained_begin_unlocked(s->bs); + /* iothread should be put */ + qatomic_set(&s->should_fail, true); + /* let the iothread do drains */ + s->allowed_to_run = true; + + /* [perform graph modifications here], as iothread is stopped */ + sleep(3); + + /* done with modifications, let the iothread drain once it resumes */ + qatomic_set(&s->should_fail, false); + + /* drained_end should resume the iothread */ + bdrv_subtree_drained_end_unlocked(s->bs); + + stop_and_tear_down_test(s); +} + +/** + * test_main_and_iothread_drain: test that if the main + * loop drains, iothread cannot possibly drain. + * + * In this test, simply let iothread and main loop concurrenly + * loop and drain together, making sure that iothread never + * reads the graph while main loop is draining. + * + * Therefore, if the main loop drains, there is no way that + * the graph can be read or written by the iothread. + */ +static void test_main_and_iothread_drain(void) +{ + ParallelDrainJob *s = setup_job_test(); + int i; + + /* let the iothread do drains from beginning */ + s->allowed_to_run = true; + job_start(&s->common.job); + + /* wait that the iothread starts and begins with drains. */ + while (!s->job_started) { + aio_poll(qemu_get_current_aio_context(), false); + } + + /* at the same time, also main loop performs drains */ + for (i = 0; i < 1000; i++) { + bdrv_subtree_drained_begin_unlocked(s->bs); + /* iothread should be put, regardless of when it drained */ + qatomic_set(&s->should_fail, true); + + /* [perform graph modifications here] */ + + /* done with modifications, let the iothread drain once it resumes */ + qatomic_set(&s->should_fail, false); + + /* drained_end should resume the iothread */ + bdrv_subtree_drained_end_unlocked(s->bs); + } + + stop_and_tear_down_test(s); +} + typedef struct TestDropBackingBlockJob { BlockJob common; @@ -2185,6 +2398,11 @@ int main(int argc, char **argv) g_test_add_func("/bdrv-drain/iothread/drain_subtree", test_iothread_drain_subtree); + g_test_add_func("/bdrv-drain/iothread/drain_main_and_then_iothread", + test_main_and_then_iothread_drain); + g_test_add_func("/bdrv-drain/iothread/drain_parallel", + test_main_and_iothread_drain); + g_test_add_func("/bdrv-drain/blockjob/drain_all", test_blockjob_drain_all); g_test_add_func("/bdrv-drain/blockjob/drain", test_blockjob_drain); g_test_add_func("/bdrv-drain/blockjob/drain_subtree", -- 2.31.1