Messages in this thread Patch in this message | | | Date | Tue, 23 Jul 2013 22:59:27 +0200 | From | Oleg Nesterov <> | Subject | [PATCH 6/6] tracing: Change remove_event_file_dir() to clear "d_subdirs"->i_private |
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Change remove_event_file_dir() ->i_private for every file we are going to remove.
tracing_open_generic_file() and tracing_release_generic_file() can go away, ftrace_enable_fops and ftrace_event_filter_fops() use tracing_open_generic() but only to check tracing_disabled.
This fixes all races with event_remove() or instance_delete(). f_op->read/write/whatever can never use the freed file/call, all event/* files were changed to check and use ->i_private under event_mutex.
Note: this doesn't not fix other problems, event_remove() can destroy the active ftrace_event_call, we need more changes but those changes are completely orthogonal.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> --- kernel/trace/trace_events.c | 40 ++++++++-------------------------------- 1 files changed, 8 insertions(+), 32 deletions(-)
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 3ae037c..298e4fa 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -428,42 +428,19 @@ static void *event_file_data(struct file *filp) static void remove_event_file_dir(struct ftrace_event_file *file) { + struct dentry *dir = file->dir; + struct dentry *child; + /* ->i_mutex is not needed, nodody can create/remove a file */ + list_for_each_entry(child, &dir->d_subdirs, d_u.d_child) + child->d_inode->i_private = NULL; + list_del(&file->list); - debugfs_remove_recursive(file->dir); + debugfs_remove_recursive(dir); remove_subsystem(file->system); kmem_cache_free(file_cachep, file); } /* - * Open and update trace_array ref count. - * Must have the current trace_array passed to it. - */ -static int tracing_open_generic_file(struct inode *inode, struct file *filp) -{ - struct ftrace_event_file *file = inode->i_private; - struct trace_array *tr = file->tr; - int ret; - - if (trace_array_get(tr) < 0) - return -ENODEV; - - ret = tracing_open_generic(inode, filp); - if (ret < 0) - trace_array_put(tr); - return ret; -} - -static int tracing_release_generic_file(struct inode *inode, struct file *filp) -{ - struct ftrace_event_file *file = inode->i_private; - struct trace_array *tr = file->tr; - - trace_array_put(tr); - - return 0; -} - -/* * __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events. */ static int @@ -1274,10 +1251,9 @@ static const struct file_operations ftrace_set_event_fops = { }; static const struct file_operations ftrace_enable_fops = { - .open = tracing_open_generic_file, + .open = tracing_open_generic, .read = event_enable_read, .write = event_enable_write, - .release = tracing_release_generic_file, .llseek = default_llseek, }; -- 1.5.5.1
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