linux-kernel - Re: [PATCH 3/9] ptrace/um: Replace PT_DTRACE with TIF

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Message-ID: <87tuaeab4u.fsf@email.froward.int.ebiederm.org>
Date:   Wed, 27 Apr 2022 08:50:25 -0500
From:   "Eric W. Biederman" <ebiederm@...ssion.com>
To:     Johannes Berg <johannes@...solutions.net>
Cc:     linux-kernel@...r.kernel.org, rjw@...ysocki.net,
        Oleg Nesterov <oleg@...hat.com>, mingo@...nel.org,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, mgorman@...e.de, bigeasy@...utronix.de,
        Will Deacon <will@...nel.org>, tj@...nel.org,
        linux-pm@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>,
        Richard Weinberger <richard@....at>,
        Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        linux-um@...ts.infradead.org, Chris Zankel <chris@...kel.net>,
        Max Filippov <jcmvbkbc@...il.com>,
        inux-xtensa@...ux-xtensa.org, Kees Cook <keescook@...omium.org>,
        Jann Horn <jannh@...gle.com>
Subject: Re: [PATCH 3/9] ptrace/um: Replace PT_DTRACE with TIF_SINGLESTEP

Johannes Berg <johannes@...solutions.net> writes:

> On Tue, 2022-04-26 at 17:52 -0500, Eric W. Biederman wrote:
>> User mode linux is the last user of the PT_DTRACE flag.  Using the flag to indicate
>> single stepping is a little confusing and worse changing tsk->ptrace without locking
>> could potentionally cause problems.
>> 
>> So use a thread info flag with a better name instead of flag in tsk->ptrace.
>> 
>> Remove the definition PT_DTRACE as uml is the last user.
>
>
> Looks fine to me.
>
> Acked-by: Johannes Berg <johannes@...solutions.net>

Thanks.

> Looking at pending patches, I don't see any conflicts from this. I'm
> guessing anyway you'll want/need to take these through some tree all
> together.

Taking them all through a single tree looks like it will be easiest.
So I am planning on taking them through my signal tree.

Now that I think of it, the lack of locking also means I want to
Cc stable.

Eric