Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758115Ab3GWVEa (ORCPT ); Tue, 23 Jul 2013 17:04:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49541 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754968Ab3GWVE2 (ORCPT ); Tue, 23 Jul 2013 17:04:28 -0400 Date: Tue, 23 Jul 2013 22:59:09 +0200 From: Oleg Nesterov To: Steven Rostedt , Masami Hiramatsu Cc: Alexander Z Lam , Arnaldo Carvalho de Melo , David Sharp , Frederic Weisbecker , Ingo Molnar , Peter Zijlstra , Srikar Dronamraju , Vaibhav Nagarnaik , "zhangwei(Jovi)" , linux-kernel@vger.kernel.org Subject: [PATCH 1/6] tracing: Turn event/id->i_private into call->event.type Message-ID: <20130723205909.GA9055@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130723205854.GA9036@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: 2463 Lines: 81 event_id_read() is racy, ftrace_event_call can be already freed by trace_remove_event_call() callers. Change event_create_dir() to pass "data = call->event.type", this is all event_id_read() needs. ftrace_event_id_fops no longer needs tracing_open_generic(). We add the new helper, event_file_data(), to read ->i_private, it will have more users. Note: currently ACCESS_ONCE() and "id != 0" check are not needed, but we are going to change event_remove/rmdir to clear ->i_mutex. Signed-off-by: Oleg Nesterov --- kernel/trace/trace_events.c | 17 ++++++++++++----- 1 files changed, 12 insertions(+), 5 deletions(-) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 76eed53..77990c4 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -409,6 +409,11 @@ static void put_system(struct ftrace_subsystem_dir *dir) mutex_unlock(&event_mutex); } +static void *event_file_data(struct file *filp) +{ + return ACCESS_ONCE(file_inode(filp)->i_private); +} + /* * Open and update trace_array ref count. * Must have the current trace_array passed to it. @@ -946,14 +951,17 @@ static int trace_format_open(struct inode *inode, struct file *file) static ssize_t event_id_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos) { - struct ftrace_event_call *call = filp->private_data; + int id = (long)event_file_data(filp); char buf[32]; int len; if (*ppos) return 0; - len = sprintf(buf, "%d\n", call->event.type); + if (unlikely(!id)) + return -ENODEV; + + len = sprintf(buf, "%d\n", id); return simple_read_from_buffer(ubuf, cnt, ppos, buf, len); } @@ -1240,7 +1248,6 @@ static const struct file_operations ftrace_event_format_fops = { }; static const struct file_operations ftrace_event_id_fops = { - .open = tracing_open_generic, .read = event_id_read, .llseek = default_llseek, }; @@ -1488,8 +1495,8 @@ event_create_dir(struct dentry *parent, #ifdef CONFIG_PERF_EVENTS if (call->event.type && call->class->reg) - trace_create_file("id", 0444, file->dir, call, - id); + trace_create_file("id", 0444, file->dir, + (void *)(long)call->event.type, id); #endif /* -- 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/