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Release the entire eventfs and tracefs hierarchy on trace_remote registration failure. Signed-off-by: Vincent Donnefort --- kernel/trace/trace_remote.c | 137 ++++++++++++++++++++++++------------ 1 file changed, 93 insertions(+), 44 deletions(-) diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c index e8cbbd01964d..a1b84290be2d 100644 --- a/kernel/trace/trace_remote.c +++ b/kernel/trace/trace_remote.c @@ -45,7 +45,8 @@ struct trace_remote { struct trace_buffer *trace_buffer; struct trace_buffer_desc *trace_buffer_desc; struct dentry *dentry; - struct eventfs_inode *eventfs; + struct eventfs_inode *eventfs_root; + struct eventfs_inode *eventfs_subdir; struct remote_event *events; unsigned long nr_events; unsigned long trace_buffer_size; @@ -60,6 +61,7 @@ struct trace_remote { static DEFINE_MUTEX(trace_remotes_lock); static LIST_HEAD(trace_remotes); +static struct dentry *trace_remotes_root; static bool trace_remote_loaded(struct trace_remote *remote) { @@ -865,23 +867,21 @@ static const struct file_operations trace_fops = { static int trace_remote_init_tracefs(const char *name, struct trace_remote *remote) { struct dentry *remote_d, *percpu_d, *d; - static struct dentry *root; - static DEFINE_MUTEX(lock); bool root_inited = false; int cpu; - guard(mutex)(&lock); + lockdep_assert_held(&trace_remotes_lock); - if (!root) { - root = tracefs_create_dir(TRACEFS_DIR, NULL); - if (!root) { + if (!trace_remotes_root) { + trace_remotes_root = tracefs_create_dir(TRACEFS_DIR, NULL); + if (!trace_remotes_root) { pr_err("Failed to create tracefs dir "TRACEFS_DIR"\n"); return -ENOMEM; } root_inited = true; } - remote_d = tracefs_create_dir(name, root); + remote_d = tracefs_create_dir(name, trace_remotes_root); if (!remote_d) { pr_err("Failed to create tracefs dir "TRACEFS_DIR"%s/\n", name); goto err; @@ -939,8 +939,8 @@ static int trace_remote_init_tracefs(const char *name, struct trace_remote *remo err: if (root_inited) { - tracefs_remove(root); - root = NULL; + tracefs_remove(trace_remotes_root); + trace_remotes_root = NULL; } else { tracefs_remove(remote_d); } @@ -948,8 +948,26 @@ static int trace_remote_init_tracefs(const char *name, struct trace_remote *remo return -ENOMEM; } +static void trace_remote_remove_tracefs(struct trace_remote *remote) +{ + lockdep_assert_held(&trace_remotes_lock); + + if (!remote->dentry) + return; + + tracefs_remove(remote->dentry); + remote->dentry = NULL; + + if (!list_empty(&trace_remotes)) + return; + + tracefs_remove(trace_remotes_root); + trace_remotes_root = NULL; +} + static int trace_remote_register_events(const char *remote_name, struct trace_remote *remote, struct remote_event *events, size_t nr_events); +static void trace_remote_unregister_events(struct trace_remote *remote); /** * trace_remote_register() - Register a Tracefs remote @@ -972,10 +990,9 @@ static int trace_remote_register_events(const char *remote_name, struct trace_re int trace_remote_register(const char *name, struct trace_remote_callbacks *cbs, void *priv, struct remote_event *events, size_t nr_events) { - struct trace_remote *remote; + struct trace_remote *remote __free(kfree) = kzalloc_obj(*remote); int ret; - remote = kzalloc_obj(*remote); if (!remote) return -ENOMEM; @@ -986,13 +1003,15 @@ int trace_remote_register(const char *name, struct trace_remote_callbacks *cbs, mutex_init(&remote->lock); init_rwsem(&remote->reader_lock); - if (trace_remote_init_tracefs(name, remote)) { - kfree(remote); - return -ENOMEM; - } + guard(mutex)(&trace_remotes_lock); + + ret = trace_remote_init_tracefs(name, remote); + if (ret) + return ret; ret = trace_remote_register_events(name, remote, events, nr_events); if (ret) { + trace_remote_remove_tracefs(remote); pr_err("Failed to register events for trace remote '%s' (%d)\n", name, ret); return ret; @@ -1000,13 +1019,16 @@ int trace_remote_register(const char *name, struct trace_remote_callbacks *cbs, ret = cbs->init ? cbs->init(remote->dentry, priv) : 0; if (ret) { + trace_remote_unregister_events(remote); + trace_remote_remove_tracefs(remote); pr_err("Init failed for trace remote '%s' (%d)\n", name, ret); - } else { - guard(mutex)(&trace_remotes_lock); - list_add(&remote->node, &trace_remotes); + return ret; } - return ret; + list_add(&remote->node, &trace_remotes); + retain_and_null_ptr(remote); + + return 0; } EXPORT_SYMBOL_GPL(trace_remote_register); @@ -1349,7 +1371,6 @@ static int remote_events_dir_callback(const char *name, umode_t *mode, void **da static int trace_remote_init_eventfs(const char *remote_name, struct trace_remote *remote, struct remote_event *evt) { - struct eventfs_inode *eventfs = remote->eventfs; static struct eventfs_entry dir_entries[] = { { .name = "enable", @@ -1374,35 +1395,37 @@ static int trace_remote_init_eventfs(const char *remote_name, struct trace_remot .callback = remote_event_callback, } }; - bool eventfs_create = false; + struct eventfs_inode *eventfs_root, *eventfs_subdir, *e; - if (!eventfs) { - eventfs = eventfs_create_events_dir("events", remote->dentry, dir_entries, - ARRAY_SIZE(dir_entries), remote); - if (IS_ERR(eventfs)) - return PTR_ERR(eventfs); + eventfs_root = remote->eventfs_root; + eventfs_subdir = remote->eventfs_subdir; + if (!eventfs_root) { + eventfs_root = eventfs_create_events_dir("events", remote->dentry, dir_entries, + ARRAY_SIZE(dir_entries), remote); + if (IS_ERR(eventfs_root)) + return PTR_ERR(eventfs_root); /* * Create similar hierarchy as local events even if a single system is supported at * the moment */ - eventfs = eventfs_create_dir(remote_name, eventfs, NULL, 0, NULL); - if (IS_ERR(eventfs)) - return PTR_ERR(eventfs); - - remote->eventfs = eventfs; - eventfs_create = true; - } - - eventfs = eventfs_create_dir(evt->name, eventfs, entries, ARRAY_SIZE(entries), evt); - if (IS_ERR(eventfs)) { - if (eventfs_create) { - eventfs_remove_events_dir(remote->eventfs); - remote->eventfs = NULL; + eventfs_subdir = eventfs_create_dir(remote_name, eventfs_root, NULL, 0, NULL); + if (IS_ERR(eventfs_subdir)) { + eventfs_remove_events_dir(eventfs_root); + return PTR_ERR(eventfs_subdir); } - return PTR_ERR(eventfs); } + e = eventfs_create_dir(evt->name, eventfs_subdir, entries, ARRAY_SIZE(entries), evt); + if (IS_ERR(e)) { + if (!remote->eventfs_root) + eventfs_remove_events_dir(eventfs_root); + return PTR_ERR(e); + } + + remote->eventfs_root = eventfs_root; + remote->eventfs_subdir = eventfs_subdir; + return 0; } @@ -1417,11 +1440,11 @@ static int trace_remote_attach_events(struct trace_remote *remote, struct remote if (evt->remote) return -EEXIST; - evt->remote = remote; - /* We need events to be sorted for efficient lookup */ if (i && evt->id <= events[i - 1].id) return -EINVAL; + + evt->remote = remote; } remote->events = events; @@ -1430,14 +1453,33 @@ static int trace_remote_attach_events(struct trace_remote *remote, struct remote return 0; } +static void trace_remote_detach_events(struct trace_remote *remote, struct remote_event *events, + size_t nr_events) +{ + int i; + + for (i = 0; i < nr_events; i++) { + struct remote_event *evt = &events[i]; + + if (evt->remote == remote) + evt->remote = NULL; + } + + remote->events = NULL; + remote->nr_events = 0; +} + static int trace_remote_register_events(const char *remote_name, struct trace_remote *remote, struct remote_event *events, size_t nr_events) { int i, ret; ret = trace_remote_attach_events(remote, events, nr_events); - if (ret) + if (ret) { + /* It is safe to call detach on a half-registered array */ + trace_remote_detach_events(remote, events, nr_events); return ret; + } for (i = 0; i < nr_events; i++) { struct remote_event *evt = &events[i]; @@ -1451,6 +1493,13 @@ static int trace_remote_register_events(const char *remote_name, struct trace_re return 0; } +static void trace_remote_unregister_events(struct trace_remote *remote) +{ + trace_remote_detach_events(remote, remote->events, remote->nr_events); + if (remote->eventfs_root) + eventfs_remove_events_dir(remote->eventfs_root); +} + static int __cmp_events(const void *key, const void *data) { const struct remote_event *evt = data; -- 2.56.0.rc1.310.g51773c2048-goog