From patchwork Fri Jun 7 21:42:38 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Eric W. Biederman" X-Patchwork-Id: 10982789 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D431992A for ; Fri, 7 Jun 2019 21:42:58 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C111428BA6 for ; Fri, 7 Jun 2019 21:42:58 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B57E328BDA; Fri, 7 Jun 2019 21:42:58 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3C75628BDA for ; Fri, 7 Jun 2019 21:42:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730078AbfFGVmx (ORCPT ); Fri, 7 Jun 2019 17:42:53 -0400 Received: from out03.mta.xmission.com ([166.70.13.233]:35017 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729731AbfFGVmx (ORCPT ); Fri, 7 Jun 2019 17:42:53 -0400 Received: from in01.mta.xmission.com ([166.70.13.51]) by out03.mta.xmission.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.87) (envelope-from ) id 1hZMdP-00052p-9m; Fri, 07 Jun 2019 15:42:51 -0600 Received: from ip72-206-97-68.om.om.cox.net ([72.206.97.68] helo=x220.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.87) (envelope-from ) id 1hZMdN-0008Ta-Vo; Fri, 07 Jun 2019 15:42:51 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Oleg Nesterov Cc: Andrew Morton , Deepa Dinamani , linux-kernel@vger.kernel.org, arnd@arndb.de, dbueso@suse.de, axboe@kernel.dk, dave@stgolabs.net, e@80x24.org, jbaron@akamai.com, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, omar.kilani@gmail.com, tglx@linutronix.de, Al Viro , Linus Torvalds , David Laight , References: <20190522032144.10995-1-deepa.kernel@gmail.com> <20190529161157.GA27659@redhat.com> <20190604134117.GA29963@redhat.com> <20190606140814.GA13440@redhat.com> <87k1dxaxcl.fsf_-_@xmission.com> Date: Fri, 07 Jun 2019 16:42:38 -0500 In-Reply-To: <87k1dxaxcl.fsf_-_@xmission.com> (Eric W. Biederman's message of "Fri, 07 Jun 2019 16:39:54 -0500") Message-ID: <8736klax81.fsf_-_@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1 (gnu/linux) MIME-Version: 1.0 X-XM-SPF: eid=1hZMdN-0008Ta-Vo;;;mid=<8736klax81.fsf_-_@xmission.com>;;;hst=in01.mta.xmission.com;;;ip=72.206.97.68;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX196inFbSGEV5ZM/UKXy2JalQH0m48f/YkU= X-SA-Exim-Connect-IP: 72.206.97.68 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: [RFC PATCH 3/5] signal: Always keep real_blocked in sync with blocked X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Except where we temporarily override blocked always keep real_blocked in sync with blocked. By always setting real_blocked when we set blocked this allows some slight efficiency and simplifications, by not having to save blocked. This also preparse the code for the removal of saved_sigmask. That should result in a massive simplification. Signed-off-by: "Eric W. Biederman" --- kernel/ptrace.c | 1 + kernel/signal.c | 14 ++++++++++---- virt/kvm/kvm_main.c | 8 -------- 3 files changed, 11 insertions(+), 12 deletions(-) diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 6f357f4fc859..6507d700d70f 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -968,6 +968,7 @@ int ptrace_request(struct task_struct *child, long request, */ spin_lock_irq(&child->sighand->siglock); child->blocked = new_set; + child->real_blocked = new_set; spin_unlock_irq(&child->sighand->siglock); clear_tsk_restore_sigmask(child); diff --git a/kernel/signal.c b/kernel/signal.c index bfa36320a4f7..fcd84f4a93c9 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2878,6 +2878,9 @@ void set_current_blocked(sigset_t *newset) { sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP)); __set_current_blocked(newset); + + /* Lockless, only current can change ->real_blocked, never from irq */ + current->real_blocked = *newset; } void __set_current_blocked(const sigset_t *newset) @@ -2928,15 +2931,20 @@ int sigprocmask(int how, sigset_t *set, sigset_t *oldset) } __set_current_blocked(&newset); + + /* Lockless, only current can change ->real_blocked, never from irq */ + tsk->real_blocked = newset; return 0; } EXPORT_SYMBOL(sigprocmask); -static int set_sigmask(sigset_t *kmask) +static int set_sigmask(sigset_t *newset) { set_restore_sigmask(); current->saved_sigmask = current->blocked; - set_current_blocked(kmask); + + sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP)); + __set_current_blocked(newset); return 0; } @@ -3440,7 +3448,6 @@ static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info, * they arrive. Unblocking is always fine, we can avoid * set_current_blocked(). */ - tsk->real_blocked = tsk->blocked; sigandsets(&tsk->blocked, &tsk->blocked, &mask); recalc_sigpending(); spin_unlock_irq(&tsk->sighand->siglock); @@ -3450,7 +3457,6 @@ static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info, HRTIMER_MODE_REL); spin_lock_irq(&tsk->sighand->siglock); __set_task_blocked(tsk, &tsk->real_blocked); - sigemptyset(&tsk->real_blocked); sig = dequeue_signal(tsk, &mask, info); } spin_unlock_irq(&tsk->sighand->siglock); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 8575a1010bfc..4bfed018574a 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2234,13 +2234,6 @@ void kvm_sigset_activate(struct kvm_vcpu *vcpu) if (!vcpu->sigset_active) return; - /* - * This does a lockless modification of ->real_blocked, which is fine - * because, only current can change ->real_blocked and all readers of - * ->real_blocked don't care as long ->real_blocked is always a subset - * of ->blocked. - */ - current->real_blocked = current->blocked; __set_current_blocked(&vcpu->sigset); } @@ -2250,7 +2243,6 @@ void kvm_sigset_deactivate(struct kvm_vcpu *vcpu) return; __set_current_blocked(¤t->real_blocked); - sigemptyset(¤t->real_blocked); } static void grow_halt_poll_ns(struct kvm_vcpu *vcpu)