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From:   ebiederm@xmission.com (Eric W. Biederman)
To:     Christian Brauner <christian.brauner@ubuntu.com>
Cc:     Bernd Edlinger <bernd.edlinger@hotmail.de>,
        Kees Cook <keescook@chromium.org>,
        Jann Horn <jannh@google.com>, Jonathan Corbet <corbet@lwn.net>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
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        Thomas Gleixner <tglx@linutronix.de>,
        Oleg Nesterov <oleg@redhat.com>,
        Frederic Weisbecker <frederic@kernel.org>,
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        Ingo Molnar <mingo@kernel.org>,
        "Peter Zijlstra \(Intel\)" <peterz@infradead.org>,
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Date:   Mon, 09 Mar 2020 15:48:55 -0500
In-Reply-To: <20200309201729.yk5sd26v4bz4gtou@wittgenstein> (Christian
        Brauner's message of "Mon, 9 Mar 2020 21:17:29 +0100")
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Subject: Re: [PATCH v2 3/5] exec: Move cleanup of posix timers on exec out of de_thread
Sender: linux-kernel-owner@vger.kernel.org
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Christian Brauner <christian.brauner@ubuntu.com> writes:

> On Mon, Mar 09, 2020 at 03:06:46PM -0500, Eric W. Biederman wrote:
>> Christian Brauner <christian.brauner@ubuntu.com> writes:
>> 
>> > On Sun, Mar 08, 2020 at 04:36:55PM -0500, Eric W. Biederman wrote:
>> >> 
>> >> These functions have very little to do with de_thread move them out
>> >> of de_thread an into flush_old_exec proper so it can be more clearly
>> >> seen what flush_old_exec is doing.
>> >> 
>> >> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
>> >> ---
>> >>  fs/exec.c | 10 +++++-----
>> >>  1 file changed, 5 insertions(+), 5 deletions(-)
>> >> 
>> >> diff --git a/fs/exec.c b/fs/exec.c
>> >> index ff74b9a74d34..215d86f77b63 100644
>> >> --- a/fs/exec.c
>> >> +++ b/fs/exec.c
>> >> @@ -1189,11 +1189,6 @@ static int de_thread(struct task_struct *tsk)
>> >
>> > While you're cleaning up de_thread() wouldn't it be good to also take
>> > the opportunity and remove the task argument from de_thread(). It's only
>> > ever used with current. Could be done in one of your patches or as a
>> > separate patch.
>> 
>> How does that affect the code generation?
>
> The same way renaming "tsk" to "me" does.
>
>> 
>> My sense is that computing current once in flush_old_exec is much
>> better than computing it in each function flush_old_exec calls.
>> I remember that computing current used to be not expensive but
>> noticable.
>> 
>> For clarity I can see renaming tsk to me.  So that it is clear we are
>> talking about the current process, and not some arbitrary process.
>
> For clarity since de_thread() uses "tsk" giving the impression that any
> task can be dethreaded while it's only ever used with current. It's just
> a suggestion since you're doing the rename tsk->me anyway it would fit
> with the series. You do whatever you want though.
> (I just remember that the same request was made once to changes I did:
> Don't pass current as arg when it's the only task passed.)

That's fair.

And I completely agree that we should at least rename tsk to me.
Just for clarity.

My apologies if I am a little short.  My little son has been an extra
handful lately.

Eric