From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753136Ab2KPQg6 (ORCPT ); Fri, 16 Nov 2012 11:36:58 -0500 Received: from out03.mta.xmission.com ([166.70.13.233]:33591 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752983Ab2KPQgz (ORCPT ); Fri, 16 Nov 2012 11:36:55 -0500 From: "Eric W. Biederman" To: Linux Containers Cc: , Oleg Nesterov , Serge Hallyn , Gao feng , Andrew Morton , "Eric W. Biederman" Date: Fri, 16 Nov 2012 08:35:46 -0800 Message-Id: <1353083750-3621-7-git-send-email-ebiederm@xmission.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1353083750-3621-1-git-send-email-ebiederm@xmission.com> References: <8739097bkk.fsf@xmission.com> <1353083750-3621-1-git-send-email-ebiederm@xmission.com> X-XM-AID: U2FsdGVkX180JtxWB/J4Tb/HERDOcSUD/yaB/gsEwBc= X-SA-Exim-Connect-IP: 98.207.153.68 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.5 XMGappySubj_01 Very gappy subject * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.1 XMSubLong Long Subject * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -0.5 BAYES_05 BODY: Bayes spam probability is 1 to 5% * [score: 0.0117] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa07 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_04 7+ unique symbols in subject * 0.0 T_TooManySym_01 4+ unique symbols in subject * 0.0 T_TooManySym_03 6+ unique symbols in subject * 0.0 T_TooManySym_02 5+ unique symbols in subject X-Spam-DCC: XMission; sa07 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Linux Containers X-Spam-Relay-Country: Subject: [PATCH 07/11] pidns: Wait in zap_pid_ns_processes until pid_ns->nr_hashed == 1 X-SA-Exim-Version: 4.2.1 (built Sun, 08 Jan 2012 03:05:19 +0000) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Eric W. Biederman" Looking at pid_ns->nr_hashed is a bit simpler and it works for disjoint process trees that an unshare or a join of a pid_namespace may create. Acked-by: "Serge E. Hallyn" Signed-off-by: "Eric W. Biederman" --- kernel/exit.c | 12 ------------ kernel/pid.c | 16 +++++++++++++--- kernel/pid_namespace.c | 15 ++++----------- 3 files changed, 17 insertions(+), 26 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 346616c..d7fe58d 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -72,18 +72,6 @@ static void __unhash_process(struct task_struct *p, bool group_dead) list_del_rcu(&p->tasks); list_del_init(&p->sibling); __this_cpu_dec(process_counts); - /* - * If we are the last child process in a pid namespace to be - * reaped, notify the reaper sleeping zap_pid_ns_processes(). - */ - if (IS_ENABLED(CONFIG_PID_NS)) { - struct task_struct *parent = p->real_parent; - - if ((task_active_pid_ns(parent)->child_reaper == parent) && - list_empty(&parent->children) && - (parent->flags & PF_EXITING)) - wake_up_process(parent); - } } list_del_rcu(&p->thread_group); } diff --git a/kernel/pid.c b/kernel/pid.c index 9c21911..6e8da29 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -273,10 +273,20 @@ void free_pid(struct pid *pid) spin_lock_irqsave(&pidmap_lock, flags); for (i = 0; i <= pid->level; i++) { struct upid *upid = pid->numbers + i; + struct pid_namespace *ns = upid->ns; hlist_del_rcu(&upid->pid_chain); - if (--upid->ns->nr_hashed == 0) { - upid->ns->nr_hashed = -1; - schedule_work(&upid->ns->proc_work); + switch(--ns->nr_hashed) { + case 1: + /* When all that is left in the pid namespace + * is the reaper wake up the reaper. The reaper + * may be sleeping in zap_pid_ns_processes(). + */ + wake_up_process(ns->child_reaper); + break; + case 0: + ns->nr_hashed = -1; + schedule_work(&ns->proc_work); + break; } } spin_unlock_irqrestore(&pidmap_lock, flags); diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index cc44db7..e106b18 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -216,22 +216,15 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns) /* * sys_wait4() above can't reap the TASK_DEAD children. - * Make sure they all go away, see __unhash_process(). + * Make sure they all go away, see free_pid(). */ for (;;) { - bool need_wait = false; - - read_lock(&tasklist_lock); - if (!list_empty(¤t->children)) { - __set_current_state(TASK_UNINTERRUPTIBLE); - need_wait = true; - } - read_unlock(&tasklist_lock); - - if (!need_wait) + set_current_state(TASK_UNINTERRUPTIBLE); + if (pid_ns->nr_hashed == 1) break; schedule(); } + __set_current_state(TASK_RUNNING); if (pid_ns->reboot) current->signal->group_exit_code = pid_ns->reboot; -- 1.7.5.4