Message-ID: <1368112875.7373.108.camel@gandalf.local.home>
Subject: Re: [PATCH 01/11] [BUGFIX] tracing: Return 0 if event_enable_func
 succeeded
From: Steven Rostedt <rostedt@goodmis.org>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: linux-kernel@vger.kernel.org,
        Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        yrl.pp-manager.tt@hitachi.com, Oleg Nesterov <oleg@redhat.com>,
        Ingo Molnar <mingo@redhat.com>, Tom Zanussi <tom.zanussi@intel.com>
Date: Thu, 09 May 2013 11:21:15 -0400
In-Reply-To: <20130509054413.30398.55650.stgit@mhiramat-M0-7522>
References: <20130509054405.30398.73831.stgit@mhiramat-M0-7522>
	 <20130509054413.30398.55650.stgit@mhiramat-M0-7522>
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On Thu, 2013-05-09 at 14:44 +0900, Masami Hiramatsu wrote:
> Return 0 instead of the number of activated ftrace if
> event_enable_func succeeded and return an error code if failed,
> beacuse 0 is success code at caller (ftrace_regex_write).
> 
> Without this fix, writing enable_event trigger on set_ftrace_filter
> always doesn't work, since event_enable_func returns 1 to
> ftrace_regex_write, it consumes 1 byte and pass input string
> without the first character again. This makes event_enable_func
> fail and disables event entry.
> 

Ah, this actually fixes two bugs! :-)

A typo will be considered success, but it also sends back to the user
that it only wrote one byte!

-- Steve


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