diff options
Diffstat (limited to 'src/journal/journald-server.c')
| -rw-r--r-- | src/journal/journald-server.c | 130 |
1 files changed, 127 insertions, 3 deletions
diff --git a/src/journal/journald-server.c b/src/journal/journald-server.c index ecf7b7a476..299b0a848f 100644 --- a/src/journal/journald-server.c +++ b/src/journal/journald-server.c @@ -78,6 +78,8 @@ #define RECHECK_SPACE_USEC (30*USEC_PER_SEC) +#define NOTIFY_SNDBUF_SIZE (8*1024*1024) + static int determine_space_for( Server *s, JournalMetrics *metrics, @@ -1457,6 +1459,126 @@ static int server_open_hostname(Server *s) { return 0; } +static int dispatch_notify_event(sd_event_source *es, int fd, uint32_t revents, void *userdata) { + Server *s = userdata; + int r; + + assert(s); + assert(s->notify_event_source == es); + assert(s->notify_fd == fd); + + if (revents != EPOLLOUT) { + log_error("Invalid events on notify file descriptor."); + return -EINVAL; + } + + /* The $NOTIFY_SOCKET is writable again, now send exactly one + * message on it. Either it's the initial READY=1 event or an + * stdout stream event. If there's nothing to write anymore, + * turn our event source off. The next time there's something + * to send it will be turned on again. */ + + if (!s->sent_notify_ready) { + static const char p[] = + "READY=1\n" + "STATUS=Processing requests..."; + ssize_t l; + + l = send(s->notify_fd, p, strlen(p), MSG_DONTWAIT); + if (l < 0) { + if (errno == EAGAIN) + return 0; + + return log_error_errno(errno, "Failed to send READY=1 notification message: %m"); + } + + s->sent_notify_ready = true; + log_debug("Sent READY=1 notification."); + + } else if (s->stdout_streams_notify_queue) + /* Dispatch one stream notification event */ + stdout_stream_send_notify(s->stdout_streams_notify_queue); + + /* Leave us enabled if there's still more to to do. */ + if (s->stdout_streams_notify_queue) + return 0; + + /* There was nothing to do anymore, let's turn ourselves off. */ + r = sd_event_source_set_enabled(es, SD_EVENT_OFF); + if (r < 0) + return log_error_errno(r, "Failed to turn off notify event source: %m"); + + return 0; +} + +static int server_connect_notify(Server *s) { + union sockaddr_union sa = { + .un.sun_family = AF_UNIX, + }; + const char *e; + int r; + + assert(s); + assert(s->notify_fd < 0); + assert(!s->notify_event_source); + + /* + So here's the problem: we'd like to send notification + messages to PID 1, but we cannot do that via sd_notify(), + since that's synchronous, and we might end up blocking on + it. Specifically: given that PID 1 might block on + dbus-daemon during IPC, and dbus-daemon is logging to us, + and might hence block on us, we might end up in a deadlock + if we block on sending PID 1 notification messages -- by + generating a full blocking circle. To avoid this, let's + create a non-blocking socket, and connect it to the + notification socket, and then wait for POLLOUT before we + send anything. This should efficiently avoid any deadlocks, + as we'll never block on PID 1, hence PID 1 can safely block + on dbus-daemon which can safely block on us again. + + Don't think that this issue is real? It is, see: + https://github.com/systemd/systemd/issues/1505 + */ + + e = getenv("NOTIFY_SOCKET"); + if (!e) + return 0; + + if ((e[0] != '@' && e[0] != '/') || e[1] == 0) { + log_error("NOTIFY_SOCKET set to an invalid value: %s", e); + return -EINVAL; + } + + if (strlen(e) > sizeof(sa.un.sun_path)) { + log_error("NOTIFY_SOCKET path too long: %s", e); + return -EINVAL; + } + + s->notify_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); + if (s->notify_fd < 0) + return log_error_errno(errno, "Failed to create notify socket: %m"); + + (void) fd_inc_sndbuf(s->notify_fd, NOTIFY_SNDBUF_SIZE); + + strncpy(sa.un.sun_path, e, sizeof(sa.un.sun_path)); + if (sa.un.sun_path[0] == '@') + sa.un.sun_path[0] = 0; + + r = connect(s->notify_fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(e)); + if (r < 0) + return log_error_errno(errno, "Failed to connect to notify socket: %m"); + + r = sd_event_add_io(s->event, &s->notify_event_source, s->notify_fd, EPOLLOUT, dispatch_notify_event, s); + if (r < 0) + return log_error_errno(r, "Failed to watch notification socket: %m"); + + /* This should fire pretty soon, which we'll use to send the + * READY=1 event. */ + + return 0; +} + int server_init(Server *s) { _cleanup_fdset_free_ FDSet *fds = NULL; int n, r, fd; @@ -1465,7 +1587,7 @@ int server_init(Server *s) { assert(s); zero(*s); - s->syslog_fd = s->native_fd = s->stdout_fd = s->dev_kmsg_fd = s->audit_fd = s->hostname_fd = -1; + s->syslog_fd = s->native_fd = s->stdout_fd = s->dev_kmsg_fd = s->audit_fd = s->hostname_fd = s->notify_fd = -1; s->compress = true; s->seal = true; @@ -1511,8 +1633,6 @@ int server_init(Server *s) { if (r < 0) return log_error_errno(r, "Failed to create event loop: %m"); - sd_event_set_watchdog(s->event, true); - n = sd_listen_fds(true); if (n < 0) return log_error_errno(n, "Failed to read listening file descriptors from environment: %m"); @@ -1637,6 +1757,8 @@ int server_init(Server *s) { server_cache_boot_id(s); server_cache_machine_id(s); + (void) server_connect_notify(s); + return system_journal_open(s, false); } @@ -1685,6 +1807,7 @@ void server_done(Server *s) { sd_event_source_unref(s->sigterm_event_source); sd_event_source_unref(s->sigint_event_source); sd_event_source_unref(s->hostname_event_source); + sd_event_source_unref(s->notify_event_source); sd_event_unref(s->event); safe_close(s->syslog_fd); @@ -1693,6 +1816,7 @@ void server_done(Server *s) { safe_close(s->dev_kmsg_fd); safe_close(s->audit_fd); safe_close(s->hostname_fd); + safe_close(s->notify_fd); if (s->rate_limit) journal_rate_limit_free(s->rate_limit); |