From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750881AbdDAFTi (ORCPT ); Sat, 1 Apr 2017 01:19:38 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:51845 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750793AbdDAFTg (ORCPT ); Sat, 1 Apr 2017 01:19:36 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Oleg Nesterov Cc: Andrew Morton , Aleksa Sarai , Andy Lutomirski , Attila Fazekas , Jann Horn , Kees Cook , Michal Hocko , Ulrich Obergfell , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org References: <20170213141452.GA30203@redhat.com> <20170224160354.GA845@redhat.com> <87shmv6ufl.fsf@xmission.com> <20170303173326.GA17899@redhat.com> <87tw7axlr0.fsf@xmission.com> <87d1dyw5iw.fsf@xmission.com> <87tw7aunuh.fsf@xmission.com> <87lgsmunmj.fsf_-_@xmission.com> <20170304170312.GB13131@redhat.com> <8760ir192p.fsf@xmission.com> <878tnkpv8h.fsf_-_@xmission.com> Date: Sat, 01 Apr 2017 00:14:17 -0500 In-Reply-To: <878tnkpv8h.fsf_-_@xmission.com> (Eric W. Biederman's message of "Sat, 01 Apr 2017 00:11:58 -0500") Message-ID: <8737dspv4m.fsf_-_@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1cuBRi-0007Ok-3Z;;;mid=<8737dspv4m.fsf_-_@xmission.com>;;;hst=in02.mta.xmission.com;;;ip=67.3.234.240;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX19wxWscE2JfHcXTcFjlKKYWgsRBiVabaHM= X-SA-Exim-Connect-IP: 67.3.234.240 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 TVD_RCVD_IP Message was received from an IP address * 1.5 TR_Symld_Words too many words that have symbols inside * 0.7 XMSubLong Long Subject * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% * [score: 0.5000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa06 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject X-Spam-DCC: XMission; sa06 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ***;Oleg Nesterov X-Spam-Relay-Country: X-Spam-Timing: total 5541 ms - load_scoreonly_sql: 0.04 (0.0%), signal_user_changed: 3.2 (0.1%), b_tie_ro: 2.3 (0.0%), parse: 1.05 (0.0%), extract_message_metadata: 12 (0.2%), get_uri_detail_list: 1.29 (0.0%), tests_pri_-1000: 6 (0.1%), tests_pri_-950: 1.13 (0.0%), tests_pri_-900: 0.98 (0.0%), tests_pri_-400: 19 (0.3%), check_bayes: 18 (0.3%), b_tokenize: 6 (0.1%), b_tok_get_all: 6 (0.1%), b_comp_prob: 1.59 (0.0%), b_tok_touch_all: 2.7 (0.0%), b_finish: 0.63 (0.0%), tests_pri_0: 234 (4.2%), check_dkim_signature: 0.45 (0.0%), check_dkim_adsp: 2.9 (0.1%), tests_pri_500: 5261 (94.9%), poll_dns_idle: 5255 (94.8%), rewrite_mail: 0.00 (0.0%) Subject: [RFC][PATCH 1/2] sighand: Count each thread group once in sighand_struct X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) 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 In practice either a thread group is either using a sighand_struct or it isn't. Therefore simplify things a bit and only increment the count in sighand_struct when a new thread group is created that uses the existing sighand_struct, and only decrement the count in sighand_struct when a thread group exits. As well as standing on it's own merits this has the potential to simply de_thread. Signed-off-by: "Eric W. Biederman" --- kernel/exit.c | 2 +- kernel/fork.c | 6 ++++-- 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index e126ebf2400c..8c5b3e106298 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -163,9 +163,9 @@ static void __exit_signal(struct task_struct *tsk) tsk->sighand = NULL; spin_unlock(&sighand->siglock); - __cleanup_sighand(sighand); clear_tsk_thread_flag(tsk, TIF_SIGPENDING); if (group_dead) { + __cleanup_sighand(sighand); flush_sigqueue(&sig->shared_pending); tty_kref_put(tty); } diff --git a/kernel/fork.c b/kernel/fork.c index 6c463c80e93d..fe6f1bf32bb9 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1295,7 +1295,8 @@ static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) struct sighand_struct *sig; if (clone_flags & CLONE_SIGHAND) { - atomic_inc(¤t->sighand->count); + if (!(clone_flags & CLONE_THREAD)) + atomic_inc(¤t->sighand->count); return 0; } sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); @@ -1896,7 +1897,8 @@ static __latent_entropy struct task_struct *copy_process( if (!(clone_flags & CLONE_THREAD)) free_signal_struct(p->signal); bad_fork_cleanup_sighand: - __cleanup_sighand(p->sighand); + if (!(clone_flags & CLONE_THREAD)) + __cleanup_sighand(p->sighand); bad_fork_cleanup_fs: exit_fs(p); /* blocking */ bad_fork_cleanup_files: -- 2.10.1