In the vhost-user-blk-test, as of now there is nothing stoping vhost-user-blk in QEMU writing to the socket right after forking off the storage daemon before it has a chance to come up properly, leaving the test hanging forever. This intermittently hanging test has caused QEMU automation failures reported multiple times on the mailing list [1].
This change makes the storage-daemon notify the vhost-user-blk-test that it is fully initialized and ready to handle client connections by creating a pidfile on initialiation. This ensures that the storage-daemon backend won't miss vhost-user messages and thereby resolves the hang. [1] https://lore.kernel.org/qemu-devel/CAFEAcA8kYpz9LiPNxnWJAPSjc=nv532bedyfynabemeohqb...@mail.gmail.com/ Signed-off-by: Raphael Norwitz <raphael.norw...@nutanix.com> --- Accidentally left a raw free() in v3. Converted it to g_free() here. tests/qtest/vhost-user-blk-test.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-) diff --git a/tests/qtest/vhost-user-blk-test.c b/tests/qtest/vhost-user-blk-test.c index 6f108a1b62..6898f55f11 100644 --- a/tests/qtest/vhost-user-blk-test.c +++ b/tests/qtest/vhost-user-blk-test.c @@ -24,6 +24,7 @@ #define TEST_IMAGE_SIZE (64 * 1024 * 1024) #define QVIRTIO_BLK_TIMEOUT_US (30 * 1000 * 1000) #define PCI_SLOT_HP 0x06 +#define PIDFILE_RETRIES 5 typedef struct { pid_t pid; @@ -885,7 +886,8 @@ static void start_vhost_user_blk(GString *cmd_line, int vus_instances, int num_queues) { const char *vhost_user_blk_bin = qtest_qemu_storage_daemon_binary(); - int i; + int i, retries; + char *daemon_pidfile_path; gchar *img_path; GString *storage_daemon_command = g_string_new(NULL); QemuStorageDaemonState *qsd; @@ -898,6 +900,9 @@ static void start_vhost_user_blk(GString *cmd_line, int vus_instances, " -object memory-backend-memfd,id=mem,size=256M,share=on " " -M memory-backend=mem -m 256M "); + daemon_pidfile_path = g_strdup_printf("/tmp/daemon-%d", getpid()); + g_assert_cmpint((uintptr_t) daemon_pidfile_path, !=, (uintptr_t) NULL); + for (i = 0; i < vus_instances; i++) { int fd; char *sock_path = create_listen_socket(&fd); @@ -914,6 +919,9 @@ static void start_vhost_user_blk(GString *cmd_line, int vus_instances, i + 1, sock_path); } + g_string_append_printf(storage_daemon_command, "--pidfile %s ", + daemon_pidfile_path); + g_test_message("starting vhost-user backend: %s", storage_daemon_command->str); pid_t pid = fork(); @@ -930,7 +938,24 @@ static void start_vhost_user_blk(GString *cmd_line, int vus_instances, execlp("/bin/sh", "sh", "-c", storage_daemon_command->str, NULL); exit(1); } + + /* + * Ensure the storage-daemon has come up properly before allowing the + * test to proceed. + */ + retries = 0; + while (access(daemon_pidfile_path, F_OK) != 0) { + g_assert_cmpint(retries, <, PIDFILE_RETRIES); + + retries++; + g_usleep(1000); + } + g_string_free(storage_daemon_command, true); + if (access(daemon_pidfile_path, F_OK) == 0) { + unlink(daemon_pidfile_path); + } + g_free(daemon_pidfile_path); qsd = g_new(QemuStorageDaemonState, 1); qsd->pid = pid; -- 2.20.1
