X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=libust%2Flttng-ust-comm.c;h=d88c4afb2346c000dedd5a96c9fa5239f37bb265;hb=381c0f1ef474e0ae8a96b3753470ca4bda45c764;hp=a5f2b0b0069de494f0fb44dd14fdde78537002e6;hpb=80e2814bbd91e86984f24a74cc75f9cc4aaa6824;p=lttng-ust.git

diff --git a/libust/lttng-ust-comm.c b/libust/lttng-ust-comm.c
index a5f2b0b0..d88c4afb 100644
--- a/libust/lttng-ust-comm.c
+++ b/libust/lttng-ust-comm.c
@@ -119,6 +119,8 @@ struct sock_info local_apps = {
 	.socket = -1,
 };
 
+static int wait_poll_fallback;
+
 extern void ltt_ring_buffer_client_overwrite_init(void);
 extern void ltt_ring_buffer_client_discard_init(void);
 extern void ltt_ring_buffer_metadata_client_init(void);
@@ -215,6 +217,9 @@ int handle_register_done(struct sock_info *sock_info)
 	if (sock_info->constructor_sem_posted)
 		return 0;
 	sock_info->constructor_sem_posted = 1;
+	if (uatomic_read(&sem_count) <= 0) {
+		return 0;
+	}
 	ret = uatomic_add_return(&sem_count, -1);
 	if (ret == 0) {
 		ret = sem_post(&constructor_wait);
@@ -277,8 +282,33 @@ end:
 	} else {
 		lur.ret_code = LTTCOMM_SESSION_FAIL;
 	}
+	if (lum->cmd == LTTNG_UST_STREAM) {
+		/*
+		 * Special-case reply to send stream info.
+		 * Use lum.u output.
+		 */
+		lur.u.stream.memory_map_size = lum->u.stream.memory_map_size;
+	}
 	ret = send_reply(sock, &lur);
 
+	if (lum->cmd == LTTNG_UST_STREAM && ret >= 0) {
+		/* we also need to send the file descriptors. */
+		ret = lttcomm_send_fds_unix_sock(sock,
+			&lum->u.stream.shm_fd, &lum->u.stream.shm_fd,
+			1, sizeof(int));
+		if (ret < 0) {
+			perror("send shm_fd");
+			goto error;
+		}
+		ret = lttcomm_send_fds_unix_sock(sock,
+			&lum->u.stream.wait_fd, &lum->u.stream.wait_fd,
+			1, sizeof(int));
+		if (ret < 0) {
+			perror("send wait_fd");
+			goto error;
+		}
+	}
+error:
 	ust_unlock();
 	return ret;
 }
@@ -485,6 +515,9 @@ void wait_for_sessiond(struct sock_info *sock_info)
 	if (lttng_ust_comm_should_quit) {
 		goto quit;
 	}
+	if (wait_poll_fallback) {
+		goto error;
+	}
 	if (!sock_info->wait_shm_mmap) {
 		sock_info->wait_shm_mmap = get_map_shm(sock_info);
 		if (!sock_info->wait_shm_mmap)
@@ -497,13 +530,17 @@ void wait_for_sessiond(struct sock_info *sock_info)
 	if (uatomic_read((int32_t *) sock_info->wait_shm_mmap) == 0) {
 		ret = futex_async((int32_t *) sock_info->wait_shm_mmap,
 			FUTEX_WAIT, 0, NULL, NULL, 0);
-		/*
-		 * FIXME: Currently, futexes on read-only shm seems to
-		 * EFAULT.
-		 */
 		if (ret < 0) {
+			if (errno == EFAULT) {
+				wait_poll_fallback = 1;
+				ERR(
+"Linux kernels 2.6.33 to 3.0 (with the exception of stable versions) "
+"do not support FUTEX_WAKE on read-only memory mappings correctly. "
+"Please upgrade your kernel "
+"(fix is commit 9ea71503a8ed9184d2d0b8ccc4d269d05f7940ae in Linux kernel "
+"mainline). LTTng-UST will use polling mode fallback.");
+			}
 			PERROR("futex");
-			sleep(5);
 		}
 	}
 	return;
@@ -514,8 +551,6 @@ quit:
 
 error:
 	ust_unlock();
-	/* Error handling: fallback on a 5 seconds sleep. */
-	sleep(5);
 	return;
 }
 
@@ -530,10 +565,25 @@ static
 void *ust_listener_thread(void *arg)
 {
 	struct sock_info *sock_info = arg;
-	int sock, ret;
+	int sock, ret, prev_connect_failed = 0, has_waited = 0;
 
 	/* Restart trying to connect to the session daemon */
 restart:
+	if (prev_connect_failed) {
+		/* Wait for sessiond availability with pipe */
+		wait_for_sessiond(sock_info);
+		if (has_waited) {
+			has_waited = 0;
+			/*
+			 * Sleep for 5 seconds before retrying after a
+			 * sequence of failure / wait / failure. This
+			 * deals with a killed or broken session daemon.
+			 */
+			sleep(5);
+		}
+		has_waited = 1;
+		prev_connect_failed = 0;
+	}
 	ust_lock();
 
 	if (lttng_ust_comm_should_quit) {
@@ -553,6 +603,7 @@ restart:
 	ret = lttcomm_connect_unix_sock(sock_info->sock_path);
 	if (ret < 0) {
 		ERR("Error connecting to %s apps socket", sock_info->name);
+		prev_connect_failed = 1;
 		/*
 		 * If we cannot find the sessiond daemon, don't delay
 		 * constructor execution.
@@ -560,9 +611,6 @@ restart:
 		ret = handle_register_done(sock_info);
 		assert(!ret);
 		ust_unlock();
-
-		/* Wait for sessiond availability with pipe */
-		wait_for_sessiond(sock_info);
 		goto restart;
 	}
 
@@ -585,6 +633,7 @@ restart:
 	ret = register_app_to_sessiond(sock);
 	if (ret < 0) {
 		ERR("Error registering to %s apps socket", sock_info->name);
+		prev_connect_failed = 1;
 		/*
 		 * If we cannot register to the sessiond daemon, don't
 		 * delay constructor execution.
@@ -592,7 +641,6 @@ restart:
 		ret = handle_register_done(sock_info);
 		assert(!ret);
 		ust_unlock();
-		wait_for_sessiond(sock_info);
 		goto restart;
 	}
 	ust_unlock();