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=-5.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 E8E1FC4363A for ; Thu, 8 Oct 2020 13:53:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8DC2B21897 for ; Thu, 8 Oct 2020 13:53:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="akNKYzlz" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729829AbgJHNxe (ORCPT ); Thu, 8 Oct 2020 09:53:34 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:46133 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729823AbgJHNxd (ORCPT ); Thu, 8 Oct 2020 09:53:33 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602165212; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Pk7ZZAadddESqYB+VY4XdoDBtWSd1nh1D4Je1J3dXys=; b=akNKYzlzqfxgwsJULHL3AhpWbjYKm+FYTrbhmjk2ieeVpKOcF/dpLTY5/lStWyt7u5WAun 0H2MzkLGgsVZX+sVlaKHk7f03l7+GiZz7qh3/DoJllHqIZ8F0XWPFYDMr1nzyfswxYtkoL agxUwjaOYkOFYQw7aYR0jy66zslg8I0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-472-ovluvz7vOjC0IwSS9V3JPA-1; Thu, 08 Oct 2020 09:53:30 -0400 X-MC-Unique: ovluvz7vOjC0IwSS9V3JPA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AECDD18C9F42; Thu, 8 Oct 2020 13:53:28 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.192.132]) by smtp.corp.redhat.com (Postfix) with SMTP id 3F50660BFA; Thu, 8 Oct 2020 13:53:27 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Thu, 8 Oct 2020 15:53:28 +0200 (CEST) Date: Thu, 8 Oct 2020 15:53:26 +0200 From: Oleg Nesterov To: Jens Axboe Cc: linux-kernel@vger.kernel.org, io-uring@vger.kernel.org, peterz@infradead.org, tglx@linutronix.de Subject: Re: [PATCH 4/6] kernel: add support for TIF_NOTIFY_SIGNAL Message-ID: <20201008135325.GG9995@redhat.com> References: <20201005150438.6628-1-axboe@kernel.dk> <20201005150438.6628-5-axboe@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201005150438.6628-5-axboe@kernel.dk> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 10/05, Jens Axboe wrote: > > static inline int signal_pending(struct task_struct *p) > { > +#ifdef TIF_NOTIFY_SIGNAL > + /* > + * TIF_NOTIFY_SIGNAL isn't really a signal, but it requires the same > + * behavior in terms of ensuring that we break out of wait loops > + * so that notify signal callbacks can be processed. > + */ > + if (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL))) > + return 1; > +#endif > return task_sigpending(p); > } perhaps we can add test_tsk_thread_mask() later... > static inline void restore_saved_sigmask_unless(bool interrupted) > { > - if (interrupted) > + if (interrupted) { > +#ifdef TIF_NOTIFY_SIGNAL > + WARN_ON(!test_thread_flag(TIF_SIGPENDING) && > + !test_thread_flag(TIF_NOTIFY_SIGNAL)); > +#else > WARN_ON(!test_thread_flag(TIF_SIGPENDING)); > - else > +#endif > + } else { > restore_saved_sigmask(); > + } I'd suggest to simply do - WARN_ON(!test_thread_flag(TIF_SIGPENDING)); + WARN_ON(!signal_pending(current); > --- a/kernel/entry/kvm.c > +++ b/kernel/entry/kvm.c > @@ -8,6 +8,9 @@ static int xfer_to_guest_mode_work(struct kvm_vcpu *vcpu, unsigned long ti_work) > do { > int ret; > > + if (ti_work & _TIF_NOTIFY_SIGNAL) > + tracehook_notify_signal(); Can't really comment this change, but to me it would be more safe to simply return -EINTR. Or perhaps even better, treat _TIF_NOTIFY_SIGNAL and _TIF_SIGPENDING equally: - if (ti_work & _TIF_SIGPENDING) { + if (ti_work & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) { kvm_handle_signal_exit(vcpu); return -EINTR; Oleg.