Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
Date:   Mon, 2 May 2022 15:38:40 +0200
From:   Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To:     "Eric W. Biederman" <ebiederm@xmission.com>
Cc:     linux-kernel@vger.kernel.org, rjw@rjwysocki.net, oleg@redhat.com,
        mingo@kernel.org, vincent.guittot@linaro.org,
        dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de,
        Will Deacon <will@kernel.org>, tj@kernel.org,
        linux-pm@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
        Richard Weinberger <richard@nod.at>,
        Anton Ivanov <anton.ivanov@cambridgegreys.com>,
        Johannes Berg <johannes@sipsolutions.net>,
        linux-um@lists.infradead.org, Chris Zankel <chris@zankel.net>,
        Max Filippov <jcmvbkbc@gmail.com>,
        linux-xtensa@linux-xtensa.org, Jann Horn <jannh@google.com>,
        Kees Cook <keescook@chromium.org>, linux-ia64@vger.kernel.org,
        tglx@linutronix.de
Subject: Re: [PATCH 0/12] ptrace: cleaning up ptrace_stop
Message-ID: <Ym/e4CrxwV3HlsJj@linutronix.de>
References: <20220421150248.667412396@infradead.org>
 <20220421150654.817117821@infradead.org>
 <87czhap9dy.fsf@email.froward.int.ebiederm.org>
 <878rrrh32q.fsf_-_@email.froward.int.ebiederm.org>
 <87k0b7v9yk.fsf_-_@email.froward.int.ebiederm.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <87k0b7v9yk.fsf_-_@email.froward.int.ebiederm.org>
Precedence: bulk

On 2022-04-29 16:46:59 [-0500], Eric W. Biederman wrote:
> 
> The states TASK_STOPPED and TASK_TRACE are special in they can not
> handle spurious wake-ups.  This plus actively depending upon and
> changing the value of tsk->__state causes problems for PREEMPT_RT and
> Peter's freezer rewrite.

PREEMPT_RT wise, I had to duct tape wait_task_inactive() and remove the
preempt-disable section in ptrace_stop() (like previously). This reduces
the amount of __state + saved_state checks and looks otherwise stable in
light testing.

Sebastian