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From: Sasha Levin <levinsasha928@gmail.com>
Date: Sun, 29 Apr 2012 16:14:16 +0200
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Subject: Re: [PATCH 01/14] sysctl: provide callback for write into ctl_table entry
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>, viro@zeniv.linux.org.uk,
        fweisbec@gmail.com, mingo@redhat.com, a.p.zijlstra@chello.nl,
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On Sun, Apr 29, 2012 at 4:00 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
> On Sun, 2012-04-29 at 14:07 +0200, Sasha Levin wrote:
>> On Sun, Apr 29, 2012 at 10:22 AM, Eric W. Biederman
>
>> Exactly twp of the patches (out of 14) are taking updates out of
>> locks. I'm quite sure that doing that in the ftrace case is perfectly
>> fine, and I'll take a second look at the sched-rt one since there
>> indeed might be a race caused due to the patch that I've missed.
>
> The update of ftrace_enable must be done under the ftrace_lock mutex.
> With the exception of ftrace_kill() which is a one shot deal that kills
> ftrace updates until a reboot.

Understood.

A fix for that could be having the sysctl modifying a different var,
and having ftrace_enabled from that under a lock, but I'm not sure if
it's worth the work for the cleanup.