From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752355Ab3EIFrL (ORCPT ); Thu, 9 May 2013 01:47:11 -0400 Received: from mail9.hitachi.co.jp ([133.145.228.44]:58003 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752176Ab3EIFrI (ORCPT ); Thu, 9 May 2013 01:47:08 -0400 X-AuditID: 85900ec0-d4ccab900000151e-90-518b385a2c62 Subject: [PATCH 06/11] [BUGFIX] tracing: Modify soft-mode only if no other referrer To: linux-kernel@vger.kernel.org, Steven Rostedt From: Masami Hiramatsu Cc: Srikar Dronamraju , Frederic Weisbecker , David Sharp , yrl.pp-manager.tt@hitachi.com, Oleg Nesterov , Ingo Molnar , Tom Zanussi , Hiraku Toyooka Date: Thu, 09 May 2013 14:44:29 +0900 Message-ID: <20130509054429.30398.7464.stgit@mhiramat-M0-7522> In-Reply-To: <20130509054405.30398.73831.stgit@mhiramat-M0-7522> References: <20130509054405.30398.73831.stgit@mhiramat-M0-7522> User-Agent: StGit/0.15 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Modify soft-mode flag only if no other soft-mode referrer (currently only the ftrace triggers) by using a reference counter in each ftrace_event_file. Without this fix, adding and removing several different enable/disable_event triggers on the same event clear soft-mode bit from the ftrace_event_file. This also happens with a typo of glob on setting triggers. e.g. # echo vfs_symlink:enable_event:net:netif_rx > set_ftrace_filter # cat events/net/netif_rx/enable 0* # echo typo_func:enable_event:net:netif_rx > set_ftrace_filter # cat events/net/netif_rx/enable 0 # cat set_ftrace_filter #### all functions enabled #### vfs_symlink:enable_event:net:netif_rx:unlimited As above, we still have a trigger, but soft-mode is gone. Signed-off-by: Masami Hiramatsu Cc: Steven Rostedt Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: David Sharp Cc: Hiraku Toyooka Cc: Tom Zanussi --- include/linux/ftrace_event.h | 1 + kernel/trace/trace_events.c | 12 ++++++++++-- 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h index 34e00fb..4372658 100644 --- a/include/linux/ftrace_event.h +++ b/include/linux/ftrace_event.h @@ -293,6 +293,7 @@ struct ftrace_event_file { * caching and such. Which is mostly OK ;-) */ unsigned long flags; + atomic_t sm_ref; /* soft-mode reference counter */ }; #define __TRACE_EVENT_FLAGS(name, value) \ diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index cc3c130..deda9ae 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -251,7 +251,8 @@ static int __ftrace_event_enable_disable(struct ftrace_event_file *file, switch (enable) { case 0: /* - * When soft_disable is set and enable is cleared, we want + * When soft_disable is set and enable is cleared, the sm_ref + * reference counter is decremented. If it reaches 0, we want * to clear the SOFT_DISABLED flag but leave the event in the * state that it was. That is, if the event was enabled and * SOFT_DISABLED isn't set, then do nothing. But if SOFT_DISABLED @@ -263,6 +264,8 @@ static int __ftrace_event_enable_disable(struct ftrace_event_file *file, * "soft enable"s (clearing the SOFT_DISABLED bit) wont work. */ if (soft_disable) { + if (atomic_dec_return(&file->sm_ref) > 0) + break; disable = file->flags & FTRACE_EVENT_FL_SOFT_DISABLED; clear_bit(FTRACE_EVENT_FL_SOFT_MODE_BIT, &file->flags); } else @@ -291,8 +294,11 @@ static int __ftrace_event_enable_disable(struct ftrace_event_file *file, */ if (!soft_disable) clear_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags); - else + else { + if (atomic_inc_return(&file->sm_ref) > 1) + break; set_bit(FTRACE_EVENT_FL_SOFT_MODE_BIT, &file->flags); + } if (!(file->flags & FTRACE_EVENT_FL_ENABLED)) { @@ -1540,6 +1546,7 @@ __trace_add_new_event(struct ftrace_event_call *call, file->event_call = call; file->tr = tr; + atomic_set(&file->sm_ref, 0); list_add(&file->list, &tr->events); return event_create_dir(tr->event_dir, file, id, enable, filter, format); @@ -1562,6 +1569,7 @@ __trace_early_add_new_event(struct ftrace_event_call *call, file->event_call = call; file->tr = tr; + atomic_set(&file->sm_ref, 0); list_add(&file->list, &tr->events); return 0;