diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 9c91c3531d83..d3cbe4bf4fab 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -468,6 +468,7 @@ enum { EVENT_FILE_FL_TRIGGER_COND_BIT, EVENT_FILE_FL_PID_FILTER_BIT, EVENT_FILE_FL_WAS_ENABLED_BIT, + EVENT_FILE_FL_FREED_BIT, }; extern struct trace_event_file *trace_get_event_file(const char *instance, @@ -606,6 +607,7 @@ extern int __kprobe_event_add_fields(struct dynevent_cmd *cmd, ...); * TRIGGER_COND - When set, one or more triggers has an associated filter * PID_FILTER - When set, the event is filtered based on pid * WAS_ENABLED - Set when enabled to know to clear trace on module removal + * FREED - File descriptor is freed, all fields should be considered invalid */ enum { EVENT_FILE_FL_ENABLED = (1 << EVENT_FILE_FL_ENABLED_BIT), @@ -619,6 +621,7 @@ enum { EVENT_FILE_FL_TRIGGER_COND = (1 << EVENT_FILE_FL_TRIGGER_COND_BIT), EVENT_FILE_FL_PID_FILTER = (1 << EVENT_FILE_FL_PID_FILTER_BIT), EVENT_FILE_FL_WAS_ENABLED = (1 << EVENT_FILE_FL_WAS_ENABLED_BIT), + EVENT_FILE_FL_FREED = (1 << EVENT_FILE_FL_FREED_BIT), }; struct trace_event_file { @@ -647,6 +650,7 @@ struct trace_event_file { * caching and such. Which is mostly OK ;-) */ unsigned long flags; + atomic_t ref; /* ref count for opened files */ atomic_t sm_ref; /* soft-mode reference counter */ atomic_t tm_ref; /* trigger-mode reference counter */ }; diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 7453840c77be..c35c805e4ab1 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4900,6 +4900,20 @@ int tracing_open_file_tr(struct inode *inode, struct file *filp) if (ret) return ret; + mutex_lock(&event_mutex); + + /* Fail if the file is marked for removal */ + if (file->flags & EVENT_FILE_FL_FREED) { + trace_array_put(file->tr); + ret = -ENODEV; + } else { + event_file_get(file); + } + + mutex_unlock(&event_mutex); + if (ret) + return ret; + filp->private_data = inode->i_private; return 0; @@ -4910,6 +4924,7 @@ int tracing_release_file_tr(struct inode *inode, struct file *filp) struct trace_event_file *file = inode->i_private; trace_array_put(file->tr); + event_file_put(file); return 0; } diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index a4a90bd3373b..c6eb116dc279 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1620,6 +1620,9 @@ extern int register_event_command(struct event_command *cmd); extern int unregister_event_command(struct event_command *cmd); extern int register_trigger_hist_enable_disable_cmds(void); +extern void event_file_get(struct trace_event_file *file); +extern void event_file_put(struct trace_event_file *file); + /** * struct event_trigger_ops - callbacks for trace event triggers * diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index f8af4a15c3a8..0a7348b90ba5 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -969,26 +969,38 @@ static void remove_subsystem(struct trace_subsystem_dir *dir) } } +void event_file_get(struct trace_event_file *file) +{ + atomic_inc(&file->ref); +} + +void event_file_put(struct trace_event_file *file) +{ + if (WARN_ON_ONCE(!atomic_read(&file->ref))) { + if (file->flags & EVENT_FILE_FL_FREED) + kmem_cache_free(file_cachep, file); + return; + } + + if (atomic_dec_and_test(&file->ref)) { + /* Count should only go to zero when it is freed */ + if (WARN_ON_ONCE(!(file->flags & EVENT_FILE_FL_FREED))) + return; + kmem_cache_free(file_cachep, file); + } +} + static void remove_event_file_dir(struct trace_event_file *file) { struct dentry *dir = file->dir; - struct dentry *child; - if (dir) { - spin_lock(&dir->d_lock); /* probably unneeded */ - list_for_each_entry(child, &dir->d_subdirs, d_child) { - if (d_really_is_positive(child)) /* probably unneeded */ - d_inode(child)->i_private = NULL; - } - spin_unlock(&dir->d_lock); - - tracefs_remove(dir); - } + tracefs_remove(dir); list_del(&file->list); remove_subsystem(file->system); free_event_filter(file->filter); - kmem_cache_free(file_cachep, file); + file->flags |= EVENT_FILE_FL_FREED; + event_file_put(file); } /* @@ -1361,7 +1373,7 @@ event_enable_read(struct file *filp, char __user *ubuf, size_t cnt, flags = file->flags; mutex_unlock(&event_mutex); - if (!file) + if (!file || flags & EVENT_FILE_FL_FREED) return -ENODEV; if (flags & EVENT_FILE_FL_ENABLED && @@ -1399,7 +1411,7 @@ event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt, ret = -ENODEV; mutex_lock(&event_mutex); file = event_file_data(filp); - if (likely(file)) + if (likely(file && !(file->flags & EVENT_FILE_FL_FREED))) ret = ftrace_event_enable_disable(file, val); mutex_unlock(&event_mutex); break; @@ -1668,7 +1680,7 @@ event_filter_read(struct file *filp, char __user *ubuf, size_t cnt, mutex_lock(&event_mutex); file = event_file_data(filp); - if (file) + if (file && !(file->flags & EVENT_FILE_FL_FREED)) print_event_filter(file, s); mutex_unlock(&event_mutex); @@ -2784,6 +2796,7 @@ trace_create_new_event(struct trace_event_call *call, atomic_set(&file->tm_ref, 0); INIT_LIST_HEAD(&file->triggers); list_add(&file->list, &tr->events); + event_file_get(file); return file; } diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index 06d6318ee537..60c34fc44a63 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -1872,6 +1872,9 @@ int apply_event_filter(struct trace_event_file *file, char *filter_string) struct event_filter *filter = NULL; int err; + if (file->flags & EVENT_FILE_FL_FREED) + return -ENODEV; + if (!strcmp(strstrip(filter_string), "0")) { filter_disable(file); filter = event_filter(file);