linux-kernel - Re: [PATCH 4/9] signal: Factor start_group_exit out of complete

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Date:   Fri, 25 Jun 2021 20:24:04 -0700
From:   Kees Cook <keescook@...omium.org>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Michael Schmitz <schmitzmic@...il.com>,
        linux-arch <linux-arch@...r.kernel.org>,
        Jens Axboe <axboe@...nel.dk>, Oleg Nesterov <oleg@...hat.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Richard Henderson <rth@...ddle.net>,
        Ivan Kokshaysky <ink@...assic.park.msu.ru>,
        Matt Turner <mattst88@...il.com>,
        alpha <linux-alpha@...r.kernel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        linux-m68k <linux-m68k@...ts.linux-m68k.org>,
        Arnd Bergmann <arnd@...nel.org>,
        Ley Foon Tan <ley.foon.tan@...el.com>,
        Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 4/9] signal: Factor start_group_exit out of
 complete_signal

On Thu, Jun 24, 2021 at 02:01:20PM -0500, Eric W. Biederman wrote:
> +static void start_group_exit_locked(struct signal_struct *signal, int exit_code)
> +{
> +	/*
> +	 * Start a group exit and wake everybody up.
> +	 * This way we don't have other threads
> +	 * running and doing things after a slower
> +	 * thread has the fatal signal pending.
> +	 */
> +	struct task_struct *t;
> +
> +	signal->flags = SIGNAL_GROUP_EXIT;
> +	signal->group_exit_code = exit_code;
> +	signal->group_stop_count = 0;
> +	__for_each_thread(signal, t) {
> +		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
> +
> +		/* Don't bother with already dead threads */
> +		if (t->exit_state)
> +			continue;
> +		sigaddset(&t->pending.signal, SIGKILL);
> +		signal_wake_up(t, 1);
> +	}

This both extracts it and changes it. For ease-of-review, maybe split
this patch into the move and then the logic changes?

-- 
Kees Cook