From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Andrzej Siewior Date: Mon, 02 May 2022 10:18:29 +0000 Subject: Re: [PATCH v2 12/12] sched,signal,ptrace: Rework TASK_TRACED, TASK_STOPPED state Message-Id: List-Id: References: <87k0b7v9yk.fsf_-_@email.froward.int.ebiederm.org> <20220429214837.386518-12-ebiederm@xmission.com> In-Reply-To: <20220429214837.386518-12-ebiederm@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: "Eric W. Biederman" Cc: linux-kernel@vger.kernel.org, rjw@rjwysocki.net, Oleg Nesterov , mingo@kernel.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de, Will Deacon , tj@kernel.org, linux-pm@vger.kernel.org, Peter Zijlstra , Richard Weinberger , Anton Ivanov , Johannes Berg , linux-um@lists.infradead.org, Chris Zankel , Max Filippov , linux-xtensa@linux-xtensa.org, Kees Cook , Jann Horn , linux-ia64@vger.kernel.org On 2022-04-29 16:48:37 [-0500], Eric W. Biederman wrote: Needs From: Peter Zijlstra (Intel) at the top. > Currently ptrace_stop() / do_signal_stop() rely on the special states > TASK_TRACED and TASK_STOPPED resp. to keep unique state. That is, this > state exists only in task->__state and nowhere else. > > There's two spots of bother with this: > > - PREEMPT_RT has task->saved_state which complicates matters, > meaning task_is_{traced,stopped}() needs to check an additional > variable. > > - An alternative freezer implementation that itself relies on a > special TASK state would loose TASK_TRACED/TASK_STOPPED and will > result in misbehaviour. > > As such, add additional state to task->jobctl to track this state > outside of task->__state. > > NOTE: this doesn't actually fix anything yet, just adds extra state. > > --EWB > * didn't add a unnecessary newline in signal.h > * Update t->jobctl in signal_wake_up and ptrace_signal_wake_up > instead of in signal_wake_up_state. This prevents the clearing > of TASK_STOPPED and TASK_TRACED from getting lost. > * Added warnings if JOBCTL_STOPPED or JOBCTL_TRACED are not cleared > > Signed-off-by: Peter Zijlstra (Intel) > Link: https://lkml.kernel.org/r/20220421150654.757693825@infradead.org > Signed-off-by: Eric W. Biederman Sebastian