X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=liblttng-ust%2Flttng-ust-comm.c;h=3a3e1d2827c82ea48ef6a79c1b89293ffbfce5b9;hb=4770bd47f35d74dd6825169bd2548d65df0217ae;hp=202ff1829c6b4746b8629c44df5fb411e9659079;hpb=321f235159b13a8a032d23fd60b9c3532790647e;p=lttng-ust.git

diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
index 202ff182..3a3e1d28 100644
--- a/liblttng-ust/lttng-ust-comm.c
+++ b/liblttng-ust/lttng-ust-comm.c
@@ -51,6 +51,7 @@
 #include "lttng-tracer-core.h"
 #include "compat.h"
 #include "../libringbuffer/tlsfixup.h"
+#include "lttng-ust-baddr.h"
 
 /*
  * Has lttng ust comm constructor been called ?
@@ -61,11 +62,119 @@ static int initialized;
  * The ust_lock/ust_unlock lock is used as a communication thread mutex.
  * Held when handling a command, also held by fork() to deal with
  * removal of threads, and by exit path.
+ *
+ * The UST lock is the centralized mutex across UST tracing control and
+ * probe registration.
+ *
+ * ust_exit_mutex must never nest in ust_mutex.
+ *
+ * ust_fork_mutex must never nest in ust_mutex.
+ *
+ * ust_mutex_nest is a per-thread nesting counter, allowing the perf
+ * counter lazy initialization called by events within the statedump,
+ * which traces while the ust_mutex is held.
+ *
+ * ust_lock nests within the dynamic loader lock (within glibc) because
+ * it is taken within the library constructor.
  */
+static pthread_mutex_t ust_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+/* Allow nesting the ust_mutex within the same thread. */
+static DEFINE_URCU_TLS(int, ust_mutex_nest);
+
+/*
+ * ust_exit_mutex protects thread_active variable wrt thread exit. It
+ * cannot be done by ust_mutex because pthread_cancel(), which takes an
+ * internal libc lock, cannot nest within ust_mutex.
+ *
+ * It never nests within a ust_mutex.
+ */
+static pthread_mutex_t ust_exit_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+/*
+ * ust_fork_mutex protects base address statedump tracing against forks. It
+ * prevents the dynamic loader lock to be taken (by base address statedump
+ * tracing) while a fork is happening, thus preventing deadlock issues with
+ * the dynamic loader lock.
+ */
+static pthread_mutex_t ust_fork_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 /* Should the ust comm thread quit ? */
 static int lttng_ust_comm_should_quit;
 
+/*
+ * Return 0 on success, -1 if should quit.
+ * The lock is taken in both cases.
+ * Signal-safe.
+ */
+int ust_lock(void)
+{
+	sigset_t sig_all_blocked, orig_mask;
+	int ret;
+
+	sigfillset(&sig_all_blocked);
+	ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
+	if (ret) {
+		ERR("pthread_sigmask: %s", strerror(ret));
+	}
+	if (!URCU_TLS(ust_mutex_nest)++)
+		pthread_mutex_lock(&ust_mutex);
+	ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
+	if (ret) {
+		ERR("pthread_sigmask: %s", strerror(ret));
+	}
+	if (lttng_ust_comm_should_quit) {
+		return -1;
+	} else {
+		return 0;
+	}
+}
+
+/*
+ * ust_lock_nocheck() can be used in constructors/destructors, because
+ * they are already nested within the dynamic loader lock, and therefore
+ * have exclusive access against execution of liblttng-ust destructor.
+ * Signal-safe.
+ */
+void ust_lock_nocheck(void)
+{
+	sigset_t sig_all_blocked, orig_mask;
+	int ret;
+
+	sigfillset(&sig_all_blocked);
+	ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
+	if (ret) {
+		ERR("pthread_sigmask: %s", strerror(ret));
+	}
+	if (!URCU_TLS(ust_mutex_nest)++)
+		pthread_mutex_lock(&ust_mutex);
+	ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
+	if (ret) {
+		ERR("pthread_sigmask: %s", strerror(ret));
+	}
+}
+
+/*
+ * Signal-safe.
+ */
+void ust_unlock(void)
+{
+	sigset_t sig_all_blocked, orig_mask;
+	int ret;
+
+	sigfillset(&sig_all_blocked);
+	ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
+	if (ret) {
+		ERR("pthread_sigmask: %s", strerror(ret));
+	}
+	if (!--URCU_TLS(ust_mutex_nest))
+		pthread_mutex_unlock(&ust_mutex);
+	ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
+	if (ret) {
+		ERR("pthread_sigmask: %s", strerror(ret));
+	}
+}
+
 /*
  * Wait for either of these before continuing to the main
  * program:
@@ -106,6 +215,8 @@ struct sock_info {
 
 	char wait_shm_path[PATH_MAX];
 	char *wait_shm_mmap;
+	/* Keep track of lazy state dump not performed yet. */
+	int statedump_pending;
 };
 
 /* Socket from app (connect) to session daemon (listen) for communication */
@@ -122,6 +233,8 @@ struct sock_info global_apps = {
 	.notify_socket = -1,
 
 	.wait_shm_path = "/" LTTNG_UST_WAIT_FILENAME,
+
+	.statedump_pending = 0,
 };
 
 /* TODO: allow global_apps_sock_path override */
@@ -135,6 +248,8 @@ struct sock_info local_apps = {
 
 	.socket = -1,
 	.notify_socket = -1,
+
+	.statedump_pending = 0,
 };
 
 static int wait_poll_fallback;
@@ -172,6 +287,7 @@ static const char *cmd_name_mapping[] = {
 
 	/* Event FD commands */
 	[ LTTNG_UST_FILTER ] = "Create Filter",
+	[ LTTNG_UST_EXCLUSION ] = "Add exclusions to event",
 };
 
 static const char *str_timeout;
@@ -213,6 +329,12 @@ void lttng_fixup_nest_count_tls(void)
 	asm volatile ("" : : "m" (URCU_TLS(lttng_ust_nest_count)));
 }
 
+static
+void lttng_fixup_ust_mutex_nest_tls(void)
+{
+	asm volatile ("" : : "m" (URCU_TLS(ust_mutex_nest)));
+}
+
 int lttng_get_notify_socket(void *owner)
 {
 	struct sock_info *info = owner;
@@ -379,6 +501,30 @@ int handle_register_done(struct sock_info *sock_info)
 	return 0;
 }
 
+/*
+ * Only execute pending statedump after the constructor semaphore has
+ * been posted by each listener thread. This means statedump will only
+ * be performed after the "registration done" command is received from
+ * each session daemon the application is connected to.
+ *
+ * This ensures we don't run into deadlock issues with the dynamic
+ * loader mutex, which is held while the constructor is called and
+ * waiting on the constructor semaphore. All operations requiring this
+ * dynamic loader lock need to be postponed using this mechanism.
+ */
+static
+void handle_pending_statedump(struct sock_info *sock_info)
+{
+	int ctor_passed = sock_info->constructor_sem_posted;
+
+	if (ctor_passed && sock_info->statedump_pending) {
+		pthread_mutex_lock(&ust_fork_mutex);
+		sock_info->statedump_pending = 0;
+		lttng_handle_pending_statedump(sock_info);
+		pthread_mutex_unlock(&ust_fork_mutex);
+	}
+}
+
 static
 int handle_message(struct sock_info *sock_info,
 		int sock, struct ustcomm_ust_msg *lum)
@@ -389,11 +535,9 @@ int handle_message(struct sock_info *sock_info,
 	union ust_args args;
 	ssize_t len;
 
-	ust_lock();
-
 	memset(&lur, 0, sizeof(lur));
 
-	if (lttng_ust_comm_should_quit) {
+	if (ust_lock()) {
 		ret = -LTTNG_UST_ERR_EXITING;
 		goto end;
 	}
@@ -487,6 +631,68 @@ int handle_message(struct sock_info *sock_info,
 		}
 		break;
 	}
+	case LTTNG_UST_EXCLUSION:
+	{
+		/* Receive exclusion names */
+		struct lttng_ust_excluder_node *node;
+		unsigned int count;
+
+		count = lum->u.exclusion.count;
+		if (count == 0) {
+			/* There are no names to read */
+			ret = 0;
+			goto error;
+		}
+		node = zmalloc(sizeof(*node) +
+				count * LTTNG_UST_SYM_NAME_LEN);
+		if (!node) {
+			ret = -ENOMEM;
+			goto error;
+		}
+		node->excluder.count = count;
+		len = ustcomm_recv_unix_sock(sock, node->excluder.names,
+				count * LTTNG_UST_SYM_NAME_LEN);
+		switch (len) {
+		case 0:	/* orderly shutdown */
+			ret = 0;
+			free(node);
+			goto error;
+		default:
+			if (len == count * LTTNG_UST_SYM_NAME_LEN) {
+				DBG("Exclusion data received");
+				break;
+			} else if (len < 0) {
+				DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
+				if (len == -ECONNRESET) {
+					ERR("%s remote end closed connection", sock_info->name);
+					ret = len;
+					free(node);
+					goto error;
+				}
+				ret = len;
+				free(node);
+				goto end;
+			} else {
+				DBG("Incorrect exclusion data message size: %zd", len);
+				ret = -EINVAL;
+				free(node);
+				goto end;
+			}
+		}
+		if (ops->cmd) {
+			ret = ops->cmd(lum->handle, lum->cmd,
+					(unsigned long) node,
+					&args, sock_info);
+			if (ret) {
+				free(node);
+			}
+			/* Don't free exclusion data if everything went fine. */
+		} else {
+			ret = -ENOSYS;
+			free(node);
+		}
+		break;
+	}
 	case LTTNG_UST_CHANNEL:
 	{
 		void *chan_data;
@@ -635,6 +841,14 @@ end:
 
 error:
 	ust_unlock();
+
+	/*
+	 * Performed delayed statedump operations outside of the UST
+	 * lock. We need to take the dynamic loader lock before we take
+	 * the UST lock internally within handle_pending_statedump().
+	  */
+	handle_pending_statedump(sock_info);
+
 	return ret;
 }
 
@@ -677,9 +891,14 @@ void cleanup_sock_info(struct sock_info *sock_info, int exiting)
 		sock_info->notify_socket = -1;
 	}
 	if (sock_info->wait_shm_mmap) {
-		ret = munmap(sock_info->wait_shm_mmap, sysconf(_SC_PAGE_SIZE));
-		if (ret) {
-			ERR("Error unmapping wait shm");
+		long page_size;
+
+		page_size = sysconf(_SC_PAGE_SIZE);
+		if (page_size > 0) {
+			ret = munmap(sock_info->wait_shm_mmap, page_size);
+			if (ret) {
+				ERR("Error unmapping wait shm");
+			}
 		}
 		sock_info->wait_shm_mmap = NULL;
 	}
@@ -705,6 +924,30 @@ int get_wait_shm(struct sock_info *sock_info, size_t mmap_size)
 	 */
 	wait_shm_fd = shm_open(sock_info->wait_shm_path, O_RDONLY, 0);
 	if (wait_shm_fd >= 0) {
+		int32_t tmp_read;
+		ssize_t len;
+		size_t bytes_read = 0;
+
+		/*
+		 * Try to read the fd. If unable to do so, try opening
+		 * it in write mode.
+		 */
+		do {
+			len = read(wait_shm_fd,
+				&((char *) &tmp_read)[bytes_read],
+				sizeof(tmp_read) - bytes_read);
+			if (len > 0) {
+				bytes_read += len;
+			}
+		} while ((len < 0 && errno == EINTR)
+			|| (len > 0 && bytes_read < sizeof(tmp_read)));
+		if (bytes_read != sizeof(tmp_read)) {
+			ret = close(wait_shm_fd);
+			if (ret) {
+				ERR("close wait_shm_fd");
+			}
+			goto open_write;
+		}
 		goto end;
 	} else if (wait_shm_fd < 0 && errno != ENOENT) {
 		/*
@@ -715,9 +958,11 @@ int get_wait_shm(struct sock_info *sock_info, size_t mmap_size)
 		ERR("Error opening shm %s", sock_info->wait_shm_path);
 		goto end;
 	}
+
+open_write:
 	/*
-	 * If the open failed because the file did not exist, try
-	 * creating it ourself.
+	 * If the open failed because the file did not exist, or because
+	 * the file was not truncated yet, try creating it ourself.
 	 */
 	URCU_TLS(lttng_ust_nest_count)++;
 	pid = fork();
@@ -826,15 +1071,20 @@ error_close:
 static
 char *get_map_shm(struct sock_info *sock_info)
 {
-	size_t mmap_size = sysconf(_SC_PAGE_SIZE);
+	long page_size;
 	int wait_shm_fd, ret;
 	char *wait_shm_mmap;
 
-	wait_shm_fd = get_wait_shm(sock_info, mmap_size);
+	page_size = sysconf(_SC_PAGE_SIZE);
+	if (page_size < 0) {
+		goto error;
+	}
+
+	wait_shm_fd = get_wait_shm(sock_info, page_size);
 	if (wait_shm_fd < 0) {
 		goto error;
 	}
-	wait_shm_mmap = mmap(NULL, mmap_size, PROT_READ,
+	wait_shm_mmap = mmap(NULL, page_size, PROT_READ,
 		  MAP_SHARED, wait_shm_fd, 0);
 	/* close shm fd immediately after taking the mmap reference */
 	ret = close(wait_shm_fd);
@@ -856,8 +1106,7 @@ void wait_for_sessiond(struct sock_info *sock_info)
 {
 	int ret;
 
-	ust_lock();
-	if (lttng_ust_comm_should_quit) {
+	if (ust_lock()) {
 		goto quit;
 	}
 	if (wait_poll_fallback) {
@@ -962,9 +1211,7 @@ restart:
 		DBG("Info: sessiond not accepting connections to %s apps socket", sock_info->name);
 		prev_connect_failed = 1;
 
-		ust_lock();
-
-		if (lttng_ust_comm_should_quit) {
+		if (ust_lock()) {
 			goto quit;
 		}
 
@@ -979,9 +1226,7 @@ restart:
 	}
 	sock_info->socket = ret;
 
-	ust_lock();
-
-	if (lttng_ust_comm_should_quit) {
+	if (ust_lock()) {
 		goto quit;
 	}
 
@@ -1022,9 +1267,7 @@ restart:
 		DBG("Info: sessiond not accepting connections to %s apps socket", sock_info->name);
 		prev_connect_failed = 1;
 
-		ust_lock();
-
-		if (lttng_ust_comm_should_quit) {
+		if (ust_lock()) {
 			goto quit;
 		}
 
@@ -1061,9 +1304,7 @@ restart:
 		WARN("Unsupported timeout value %ld", timeout);
 	}
 
-	ust_lock();
-
-	if (lttng_ust_comm_should_quit) {
+	if (ust_lock()) {
 		goto quit;
 	}
 
@@ -1094,8 +1335,7 @@ restart:
 		switch (len) {
 		case 0:	/* orderly shutdown */
 			DBG("%s lttng-sessiond has performed an orderly shutdown", sock_info->name);
-			ust_lock();
-			if (lttng_ust_comm_should_quit) {
+			if (ust_lock()) {
 				goto quit;
 			}
 			/*
@@ -1134,8 +1374,7 @@ restart:
 
 	}
 end:
-	ust_lock();
-	if (lttng_ust_comm_should_quit) {
+	if (ust_lock()) {
 		goto quit;
 	}
 	/* Cleanup socket handles before trying to reconnect */
@@ -1144,11 +1383,22 @@ end:
 	goto restart;	/* try to reconnect */
 
 quit:
-	sock_info->thread_active = 0;
 	ust_unlock();
+
+	pthread_mutex_lock(&ust_exit_mutex);
+	sock_info->thread_active = 0;
+	pthread_mutex_unlock(&ust_exit_mutex);
 	return NULL;
 }
 
+/*
+ * Weak symbol to call when the ust malloc wrapper is not loaded.
+ */
+__attribute__((weak))
+void lttng_ust_malloc_wrapper_init(void)
+{
+}
+
 /*
  * sessiond monitoring thread: monitor presence of global and per-user
  * sessiond by polling the application common named pipe.
@@ -1173,6 +1423,7 @@ void __attribute__((constructor)) lttng_ust_init(void)
 	lttng_fixup_vtid_tls();
 	lttng_fixup_nest_count_tls();
 	lttng_fixup_procname_tls();
+	lttng_fixup_ust_mutex_nest_tls();
 
 	/*
 	 * We want precise control over the order in which we construct
@@ -1182,12 +1433,18 @@ void __attribute__((constructor)) lttng_ust_init(void)
 	 */
 	init_usterr();
 	init_tracepoint();
+	lttng_ust_baddr_statedump_init();
 	lttng_ring_buffer_metadata_client_init();
 	lttng_ring_buffer_client_overwrite_init();
 	lttng_ring_buffer_client_overwrite_rt_init();
 	lttng_ring_buffer_client_discard_init();
 	lttng_ring_buffer_client_discard_rt_init();
+	lttng_perf_counter_init();
 	lttng_context_init();
+	/*
+	 * Invoke ust malloc wrapper init before starting other threads.
+	 */
+	lttng_ust_malloc_wrapper_init();
 
 	timeout_mode = get_constructor_timeout(&constructor_timeout);
 
@@ -1219,24 +1476,24 @@ void __attribute__((constructor)) lttng_ust_init(void)
 		ERR("pthread_attr_setdetachstate: %s", strerror(ret));
 	}
 
-	ust_lock();
+	pthread_mutex_lock(&ust_exit_mutex);
 	ret = pthread_create(&global_apps.ust_listener, &thread_attr,
 			ust_listener_thread, &global_apps);
 	if (ret) {
 		ERR("pthread_create global: %s", strerror(ret));
 	}
 	global_apps.thread_active = 1;
-	ust_unlock();
+	pthread_mutex_unlock(&ust_exit_mutex);
 
 	if (local_apps.allowed) {
-		ust_lock();
+		pthread_mutex_lock(&ust_exit_mutex);
 		ret = pthread_create(&local_apps.ust_listener, &thread_attr,
 				ust_listener_thread, &local_apps);
 		if (ret) {
 			ERR("pthread_create local: %s", strerror(ret));
 		}
 		local_apps.thread_active = 1;
-		ust_unlock();
+		pthread_mutex_unlock(&ust_exit_mutex);
 	} else {
 		handle_register_done(&local_apps);
 	}
@@ -1291,11 +1548,13 @@ void lttng_ust_cleanup(int exiting)
 	lttng_ust_abi_exit();
 	lttng_ust_events_exit();
 	lttng_context_exit();
+	lttng_perf_counter_exit();
 	lttng_ring_buffer_client_discard_rt_exit();
 	lttng_ring_buffer_client_discard_exit();
 	lttng_ring_buffer_client_overwrite_rt_exit();
 	lttng_ring_buffer_client_overwrite_exit();
 	lttng_ring_buffer_metadata_client_exit();
+	lttng_ust_baddr_statedump_destroy();
 	exit_tracepoint();
 	if (!exiting) {
 		/* Reinitialize values for fork */
@@ -1320,9 +1579,11 @@ void __attribute__((destructor)) lttng_ust_exit(void)
 	 * mutexes to ensure it is not in a mutex critical section when
 	 * pthread_cancel is later called.
 	 */
-	ust_lock();
+	ust_lock_nocheck();
 	lttng_ust_comm_should_quit = 1;
+	ust_unlock();
 
+	pthread_mutex_lock(&ust_exit_mutex);
 	/* cancel threads */
 	if (global_apps.thread_active) {
 		ret = pthread_cancel(global_apps.ust_listener);
@@ -1342,7 +1603,7 @@ void __attribute__((destructor)) lttng_ust_exit(void)
 			local_apps.thread_active = 0;
 		}
 	}
-	ust_unlock();
+	pthread_mutex_unlock(&ust_exit_mutex);
 
 	/*
 	 * Do NOT join threads: use of sys_futex makes it impossible to
@@ -1381,7 +1642,10 @@ void ust_before_fork(sigset_t *save_sigset)
 	if (ret == -1) {
 		PERROR("sigprocmask");
 	}
-	ust_lock();
+
+	pthread_mutex_lock(&ust_fork_mutex);
+
+	ust_lock_nocheck();
 	rcu_bp_before_fork();
 }
 
@@ -1391,6 +1655,9 @@ static void ust_after_fork_common(sigset_t *restore_sigset)
 
 	DBG("process %d", getpid());
 	ust_unlock();
+
+	pthread_mutex_unlock(&ust_fork_mutex);
+
 	/* Restore signals */
 	ret = sigprocmask(SIG_SETMASK, restore_sigset, NULL);
 	if (ret == -1) {
@@ -1430,3 +1697,9 @@ void ust_after_fork_child(sigset_t *restore_sigset)
 	ust_after_fork_common(restore_sigset);
 	lttng_ust_init();
 }
+
+void lttng_ust_sockinfo_session_enabled(void *owner)
+{
+	struct sock_info *sock_info = owner;
+	sock_info->statedump_pending = 1;
+}