Merge pull request #1745 from poettering/journal-deadlock

Make sure journald never blocks on sd_notify() to PID 1

1 files changed, 62 insertions, 6 deletions

diff --git a/src/journal/journald-stream.c b/src/journal/journald-stream.c
index 5300c61c02..fb6afee171 100644
--- a/src/journal/journald-stream.c
+++ b/src/journal/journald-stream.c
@@ -79,6 +79,7 @@ struct StdoutStream {
         bool forward_to_console:1;
 
         bool fdstore:1;
+        bool in_notify_queue:1;
 
         char buffer[LINE_MAX+1];
         size_t length;
@@ -88,6 +89,7 @@ struct StdoutStream {
         char *state_file;
 
         LIST_FIELDS(StdoutStream, stdout_stream);
+        LIST_FIELDS(StdoutStream, stdout_stream_notify_queue);
 };
 
 void stdout_stream_free(StdoutStream *s) {
@@ -98,6 +100,9 @@ void stdout_stream_free(StdoutStream *s) {
                 assert(s->server->n_stdout_streams > 0);
                 s->server->n_stdout_streams --;
                 LIST_REMOVE(stdout_stream, s->server->stdout_streams, s);
+
+                if (s->in_notify_queue)
+                        LIST_REMOVE(stdout_stream_notify_queue, s->server->stdout_streams_notify_queue, s);
         }
 
         if (s->event_source) {
@@ -121,7 +126,7 @@ static void stdout_stream_destroy(StdoutStream *s) {
                 return;
 
         if (s->state_file)
-                unlink(s->state_file);
+                (void) unlink(s->state_file);
 
         stdout_stream_free(s);
 }
@@ -200,11 +205,15 @@ static int stdout_stream_save(StdoutStream *s) {
                 goto fail;
         }
 
-        /* Store the connection fd in PID 1, so that we get it passed
-         * in again on next start */
-        if (!s->fdstore) {
-                sd_pid_notify_with_fds(0, false, "FDSTORE=1", &s->fd, 1);
-                s->fdstore = true;
+        if (!s->fdstore && !s->in_notify_queue) {
+                LIST_PREPEND(stdout_stream_notify_queue, s->server->stdout_streams_notify_queue, s);
+                s->in_notify_queue = true;
+
+                if (s->server->notify_event_source) {
+                        r = sd_event_source_set_enabled(s->server->notify_event_source, SD_EVENT_ON);
+                        if (r < 0)
+                                log_warning_errno(r, "Failed to enable notify event source: %m");
+                }
         }
 
         return 0;
@@ -729,3 +738,50 @@ int server_open_stdout_socket(Server *s) {
 
         return 0;
 }
+
+void stdout_stream_send_notify(StdoutStream *s) {
+        struct iovec iovec = {
+                .iov_base = (char*) "FDSTORE=1",
+                .iov_len = strlen("FDSTORE=1"),
+        };
+        struct msghdr msghdr = {
+                .msg_iov = &iovec,
+                .msg_iovlen = 1,
+        };
+        struct cmsghdr *cmsg;
+        ssize_t l;
+
+        assert(s);
+        assert(!s->fdstore);
+        assert(s->in_notify_queue);
+        assert(s->server);
+        assert(s->server->notify_fd >= 0);
+
+        /* Store the connection fd in PID 1, so that we get it passed
+         * in again on next start */
+
+        msghdr.msg_controllen = CMSG_SPACE(sizeof(int));
+        msghdr.msg_control = alloca0(msghdr.msg_controllen);
+
+        cmsg = CMSG_FIRSTHDR(&msghdr);
+        cmsg->cmsg_level = SOL_SOCKET;
+        cmsg->cmsg_type = SCM_RIGHTS;
+        cmsg->cmsg_len = CMSG_LEN(sizeof(int));
+
+        memcpy(CMSG_DATA(cmsg), &s->fd, sizeof(int));
+
+        l = sendmsg(s->server->notify_fd, &msghdr, MSG_DONTWAIT|MSG_NOSIGNAL);
+        if (l < 0) {
+                if (errno == EAGAIN)
+                        return;
+
+                log_error_errno(errno, "Failed to send stream file descriptor to service manager: %m");
+        } else {
+                log_debug("Successfully sent stream file descriptor to service manager.");
+                s->fdstore = 1;
+        }
+
+        LIST_REMOVE(stdout_stream_notify_queue, s->server->stdout_streams_notify_queue, s);
+        s->in_notify_queue = false;
+
+}