From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 521FCC49EAB for ; Thu, 24 Jun 2021 19:03:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 39ABB613D3 for ; Thu, 24 Jun 2021 19:03:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232678AbhFXTFV (ORCPT ); Thu, 24 Jun 2021 15:05:21 -0400 Received: from out03.mta.xmission.com ([166.70.13.233]:59868 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232537AbhFXTFU (ORCPT ); Thu, 24 Jun 2021 15:05:20 -0400 Received: from in02.mta.xmission.com ([166.70.13.52]:33542) by out03.mta.xmission.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1lwUct-008eU2-2h; Thu, 24 Jun 2021 13:02:59 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95]:47212 helo=email.xmission.com) by in02.mta.xmission.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1lwUcr-003HZQ-M6; Thu, 24 Jun 2021 13:02:58 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Linus Torvalds Cc: Al Viro , Michael Schmitz , linux-arch , Jens Axboe , Oleg Nesterov , Linux Kernel Mailing List , Richard Henderson , Ivan Kokshaysky , Matt Turner , alpha , Geert Uytterhoeven , linux-m68k , Arnd Bergmann , Ley Foon Tan , Tejun Heo , Kees Cook References: <87sg1lwhvm.fsf@disp2133> <6e47eff8-d0a4-8390-1222-e975bfbf3a65@gmail.com> <924ec53c-2fd9-2e1c-bbb1-3fda49809be4@gmail.com> <87eed4v2dc.fsf@disp2133> <5929e116-fa61-b211-342a-c706dcb834ca@gmail.com> <87fsxjorgs.fsf@disp2133> <87a6njf0ia.fsf@disp2133> <87tulpbp19.fsf@disp2133> <87zgvgabw1.fsf@disp2133> <875yy3850g.fsf_-_@disp2133> Date: Thu, 24 Jun 2021 14:02:50 -0500 In-Reply-To: <875yy3850g.fsf_-_@disp2133> (Eric W. Biederman's message of "Thu, 24 Jun 2021 13:57:35 -0500") Message-ID: <87y2az5bmt.fsf_-_@disp2133> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1lwUcr-003HZQ-M6;;;mid=<87y2az5bmt.fsf_-_@disp2133>;;;hst=in02.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1/lXuwnEpH9d/WqY5Bt5fTe321yxl0TTdU= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: [PATCH 7/9] signal: Make individual tasks exiting a first class concept. X-SA-Exim-Version: 4.2.1 (built Sat, 08 Feb 2020 21:53:50 +0000) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Implement start_task_exit_locked and rewrite the de_thread logic in exec using it. Calling start_task_exit_locked is equivalent to asyncrhonously calling exit(2) aka pthread_exit on a task. Signed-off-by: "Eric W. Biederman" --- fs/exec.c | 10 +++++++++- include/linux/sched/jobctl.h | 2 ++ include/linux/sched/signal.h | 1 + kernel/signal.c | 37 ++++++++++++++++-------------------- 4 files changed, 28 insertions(+), 22 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index 18594f11c31f..b6f50213f0a0 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1040,6 +1040,7 @@ static int de_thread(struct task_struct *tsk) struct signal_struct *sig = tsk->signal; struct sighand_struct *oldsighand = tsk->sighand; spinlock_t *lock = &oldsighand->siglock; + struct task_struct *t; if (thread_group_empty(tsk)) goto no_thread_group; @@ -1058,7 +1059,14 @@ static int de_thread(struct task_struct *tsk) } sig->group_exit_task = tsk; - sig->notify_count = zap_other_threads(tsk); + sig->group_stop_count = 0; + sig->notify_count = 0; + __for_each_thread(sig, t) { + if (t == tsk) + continue; + sig->notify_count++; + start_task_exit_locked(t, SIGKILL); + } if (!thread_group_leader(tsk)) sig->notify_count--; diff --git a/include/linux/sched/jobctl.h b/include/linux/sched/jobctl.h index fa067de9f1a9..e94833b0c819 100644 --- a/include/linux/sched/jobctl.h +++ b/include/linux/sched/jobctl.h @@ -19,6 +19,7 @@ struct task_struct; #define JOBCTL_TRAPPING_BIT 21 /* switching to TRACED */ #define JOBCTL_LISTENING_BIT 22 /* ptracer is listening for events */ #define JOBCTL_TRAP_FREEZE_BIT 23 /* trap for cgroup freezer */ +#define JOBCTL_TASK_EXITING_BIT 31 /* the task is exiting */ #define JOBCTL_STOP_DEQUEUED (1UL << JOBCTL_STOP_DEQUEUED_BIT) #define JOBCTL_STOP_PENDING (1UL << JOBCTL_STOP_PENDING_BIT) @@ -28,6 +29,7 @@ struct task_struct; #define JOBCTL_TRAPPING (1UL << JOBCTL_TRAPPING_BIT) #define JOBCTL_LISTENING (1UL << JOBCTL_LISTENING_BIT) #define JOBCTL_TRAP_FREEZE (1UL << JOBCTL_TRAP_FREEZE_BIT) +#define JOBCTL_TASK_EXITING (1UL << JOBCTL_TASK_EXITING_BIT) #define JOBCTL_TRAP_MASK (JOBCTL_TRAP_STOP | JOBCTL_TRAP_NOTIFY) #define JOBCTL_PENDING_MASK (JOBCTL_STOP_PENDING | JOBCTL_TRAP_MASK) diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index c007e55cb119..a958381ba4a9 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -429,6 +429,7 @@ static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume) } void start_group_exit(int exit_code); +void start_task_exit_locked(struct task_struct *task, int exit_code); void task_join_group_stop(struct task_struct *task); diff --git a/kernel/signal.c b/kernel/signal.c index 95a076af600a..afbc001220dd 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -264,6 +264,12 @@ static inline void print_dropped_signal(int sig) current->comm, current->pid, sig); } +static void task_set_jobctl_exiting(struct task_struct *task, int exit_code) +{ + WARN_ON_ONCE(task->jobctl & ~JOBCTL_STOP_SIGMASK); + task->jobctl = JOBCTL_TASK_EXITING | (exit_code & JOBCTL_STOP_SIGMASK); +} + /** * task_set_jobctl_pending - set jobctl pending bits * @task: target task @@ -1407,28 +1413,15 @@ int force_sig_info(struct kernel_siginfo *info) return force_sig_info_to_task(info, current, false); } -/* - * Nuke all other threads in the group. - */ -int zap_other_threads(struct task_struct *p) +void start_task_exit_locked(struct task_struct *task, int exit_code) { - struct task_struct *t = p; - int count = 0; - - p->signal->group_stop_count = 0; - - while_each_thread(p, t) { - task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); - count++; - - /* Don't bother with already dead threads */ - if (t->exit_state) - continue; - sigaddset(&t->pending.signal, SIGKILL); - signal_wake_up(t, 1); + task_clear_jobctl_pending(task, JOBCTL_PENDING_MASK); + /* Only bother with threads that might be alive */ + if (!task->exit_state) { + task_set_jobctl_exiting(task, exit_code); + sigaddset(&task->pending.signal, SIGKILL); + signal_wake_up(task, 1); } - - return count; } struct sighand_struct *__lock_task_sighand(struct task_struct *tsk, @@ -2714,7 +2707,7 @@ bool get_signal(struct ksignal *ksig) } /* Has this task already been marked for death? */ - if (signal_group_exit(signal)) { + if (signal_group_exit(signal) || (current->jobctl & JOBCTL_TASK_EXITING)) { ksig->info.si_signo = signr = SIGKILL; sigdelset(¤t->pending.signal, SIGKILL); trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO, @@ -2874,6 +2867,8 @@ bool get_signal(struct ksignal *ksig) if (signal_group_exit(signal)) { /* Another thread got here before we took the lock. */ exit_code = signal->group_exit_code; + } else if (current->jobctl & JOBCTL_TASK_EXITING) { + exit_code = current->jobctl & JOBCTL_STOP_SIGMASK; } else { start_group_exit_locked(signal, exit_code); } -- 2.20.1