Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759310Ab3GZRbP (ORCPT ); Fri, 26 Jul 2013 13:31:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38719 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758267Ab3GZRbM (ORCPT ); Fri, 26 Jul 2013 13:31:12 -0400 Date: Fri, 26 Jul 2013 19:25:51 +0200 From: Oleg Nesterov To: Steven Rostedt , Masami Hiramatsu Cc: Alexander Z Lam , Arnaldo Carvalho de Melo , David Sharp , Frederic Weisbecker , Greg Kroah-Hartman , Ingo Molnar , Peter Zijlstra , Srikar Dronamraju , Vaibhav Nagarnaik , "zhangwei(Jovi)" , linux-kernel@vger.kernel.org Subject: [PATCH v2 6/6] tracing: Change remove_event_file_dir() to clear "d_subdirs"->i_private Message-ID: <20130726172551.GA3632@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130726172513.GA3586@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2914 Lines: 96 Change remove_event_file_dir() to clear ->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 --- kernel/trace/trace_events.c | 41 +++++++++-------------------------------- 1 files changed, 9 insertions(+), 32 deletions(-) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 2a4f68a..1112fa0 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -428,42 +428,20 @@ 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, nobody 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 @@ -1277,10 +1255,9 @@ 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/