X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=src%2Fcommon%2Ffd-tracker%2Ffd-tracker.c;h=a9921fa847eff9d6c361b772ad34b224ac13e932;hb=ca806b0b247f89c62ac628a7779ae84049a8c2d7;hp=417859abe889e0e8b94eabe88dd9fd0d00376f9c;hpb=ab5be9fa2eb5ba9600a82cd18fd3cfcbac69169a;p=lttng-tools.git

diff --git a/src/common/fd-tracker/fd-tracker.c b/src/common/fd-tracker/fd-tracker.c
index 417859abe..a9921fa84 100644
--- a/src/common/fd-tracker/fd-tracker.c
+++ b/src/common/fd-tracker/fd-tracker.c
@@ -210,7 +210,7 @@ static void fs_handle_tracked_log(struct fs_handle_tracked *handle)
 	const char *path;
 
 	pthread_mutex_lock(&handle->lock);
-	lttng_inode_get_location(handle->inode, NULL, &path);
+	lttng_inode_borrow_location(handle->inode, NULL, &path);
 
 	if (handle->fd >= 0) {
 		DBG_NO_LOC("    %s [active, fd %d%s]", path, handle->fd,
@@ -230,8 +230,9 @@ static int fs_handle_tracked_suspend(struct fs_handle_tracked *handle)
 	const struct lttng_directory_handle *node_directory_handle;
 
 	pthread_mutex_lock(&handle->lock);
-	lttng_inode_get_location(handle->inode, &node_directory_handle, &path);
-	assert(handle->fd >= 0);
+	lttng_inode_borrow_location(
+			handle->inode, &node_directory_handle, &path);
+	LTTNG_ASSERT(handle->fd >= 0);
 	if (handle->in_use) {
 		/* This handle can't be suspended as it is currently in use. */
 		ret = -EAGAIN;
@@ -288,10 +289,11 @@ static int fs_handle_tracked_restore(struct fs_handle_tracked *handle)
 	const char *path;
 	const struct lttng_directory_handle *node_directory_handle;
 
-	lttng_inode_get_location(handle->inode, &node_directory_handle, &path);
+	lttng_inode_borrow_location(
+			handle->inode, &node_directory_handle, &path);
 
-	assert(handle->fd == -1);
-	assert(path);
+	LTTNG_ASSERT(handle->fd == -1);
+	LTTNG_ASSERT(path);
 	ret = open_from_properties(
 			node_directory_handle, path, &handle->properties);
 	if (ret < 0) {
@@ -455,6 +457,9 @@ int fd_tracker_destroy(struct fd_tracker *tracker)
 {
 	int ret = 0;
 
+	if (!tracker) {
+		goto end;
+	}
 	/*
 	 * Refuse to destroy the tracker as fs_handles may still old
 	 * weak references to the tracker.
@@ -472,7 +477,7 @@ int fd_tracker_destroy(struct fd_tracker *tracker)
 
 	if (tracker->unsuspendable_fds) {
 		ret = cds_lfht_destroy(tracker->unsuspendable_fds, NULL);
-		assert(!ret);
+		LTTNG_ASSERT(!ret);
 	}
 
 	lttng_inode_registry_destroy(tracker->inode_registry);
@@ -632,7 +637,7 @@ int fd_tracker_open_unsuspendable_fd(struct fd_tracker *tracker,
 		} else {
 			/*
 			 * There are not enough active suspendable file
-			 * descriptors to open a new fd and still accomodate the
+			 * descriptors to open a new fd and still accommodates the
 			 * tracker's capacity.
 			 */
 			WARN("Cannot open unsuspendable fd, too many unsuspendable file descriptors are opened (%u)",
@@ -829,7 +834,7 @@ static int fs_handle_tracked_get_fd(struct fs_handle *_handle)
 	 */
 	pthread_mutex_lock(&handle->tracker->lock);
 	pthread_mutex_lock(&handle->lock);
-	assert(!handle->in_use);
+	LTTNG_ASSERT(!handle->in_use);
 
 	handle->tracker->stats.uses++;
 	if (handle->fd >= 0) {
@@ -882,6 +887,7 @@ static int fs_handle_tracked_close(struct fs_handle *_handle)
 	const char *path = NULL;
 	struct fs_handle_tracked *handle =
 			container_of(_handle, struct fs_handle_tracked, parent);
+	struct lttng_directory_handle *inode_directory_handle = NULL;
 
 	if (!handle) {
 		ret = -EINVAL;
@@ -891,7 +897,29 @@ static int fs_handle_tracked_close(struct fs_handle *_handle)
 	pthread_mutex_lock(&handle->tracker->lock);
 	pthread_mutex_lock(&handle->lock);
 	if (handle->inode) {
-		lttng_inode_get_location(handle->inode, NULL, &path);
+		lttng_inode_borrow_location(handle->inode, NULL, &path);
+		/*
+		 * Here a reference to the inode's directory handle is acquired
+		 * to prevent the last reference to it from being released while
+		 * the tracker's lock is taken.
+		 *
+		 * If this wasn't done, the directory handle could attempt to
+		 * close its underlying directory file descriptor, which would
+		 * attempt to lock the tracker's lock, resulting in a deadlock.
+		 *
+		 * Since a new reference to the directory handle is taken within
+		 * the scope of this function, it is not possible for the last
+		 * reference to the inode's location directory handle to be
+		 * released during the call to lttng_inode_put().
+		 *
+		 * We wait until the tracker's lock is released to release the
+		 * reference. Hence, the call to the tracker is delayed just
+		 * enough to not attempt to recursively acquire the tracker's
+		 * lock twice.
+		 */
+		inode_directory_handle =
+				lttng_inode_get_location_directory_handle(
+						handle->inode);
 	}
 	fd_tracker_untrack(handle->tracker, handle);
 	if (handle->fd >= 0) {
@@ -900,7 +928,7 @@ static int fs_handle_tracked_close(struct fs_handle *_handle)
 		 * isn't much the user can do about it.
 		 */
 		if (close(handle->fd)) {
-			PERROR("Failed to close the file descritptor (%d) of fs handle to %s, close() returned",
+			PERROR("Failed to close the file descriptor (%d) of fs handle to %s, close() returned",
 					handle->fd, path ? path : "Unknown");
 		}
 		handle->fd = -1;
@@ -912,6 +940,7 @@ static int fs_handle_tracked_close(struct fs_handle *_handle)
 	pthread_mutex_destroy(&handle->lock);
 	pthread_mutex_unlock(&handle->tracker->lock);
 	free(handle);
+	lttng_directory_handle_put(inode_directory_handle);
 end:
 	return ret;
 }