From patchwork Mon Dec 4 14:36:41 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Serhii Popovych X-Patchwork-Id: 844279 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=kvm-ppc-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3yr6sc55c6z9t6n for ; Tue, 5 Dec 2017 01:37:24 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754266AbdLDOhL (ORCPT ); Mon, 4 Dec 2017 09:37:11 -0500 Received: from mx1.redhat.com ([209.132.183.28]:6579 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754173AbdLDOgq (ORCPT ); Mon, 4 Dec 2017 09:36:46 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9A247C014182; Mon, 4 Dec 2017 14:36:45 +0000 (UTC) Received: from tuxracer.localdomain (dhcp7-133.lab.eng.rdu.redhat.com [10.12.7.133]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 854266F92F; Mon, 4 Dec 2017 14:36:44 +0000 (UTC) From: Serhii Popovych To: linux-kernel@vger.kernel.org Cc: kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, michael@ellerman.id.au, paulus@samba.org, linuxppc-dev@lists.ozlabs.org, david@gibson.dropbear.id.au Subject: [PATCH v2 1/2] KVM: PPC: Book3S HV: Drop prepare_done from struct kvm_resize_hpt and cleanups Date: Mon, 4 Dec 2017 09:36:41 -0500 Message-Id: <1512398202-8195-2-git-send-email-spopovyc@redhat.com> In-Reply-To: <1512398202-8195-1-git-send-email-spopovyc@redhat.com> References: <1512398202-8195-1-git-send-email-spopovyc@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Mon, 04 Dec 2017 14:36:45 +0000 (UTC) Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org Currently the kvm_resize_hpt structure has two fields relevant to the state of an ongoing resize: 'prepare_done', which indicates whether the worker thread has completed or not, and 'error' which indicates whether it was successful or not. Since the success/failure isn't known until completion, this is confusingly redundant. This patch consolidates the information into just the 'error' value: -EBUSY indicates the worked is still in progress, other negative values indicate (completed) failure, 0 indicates successful completion. As a bonus this reduces size of struct kvm_resize_hpt by __alignof__(struct kvm_hpt_info) and saves few bytes of code. While there correct comment in struct kvm_resize_hpt which references a non-existent semaphore (leftover from an early draft). Assert with WARN_ON() in case of HPT allocation thread work runs more than once for resize request or resize_hpt_allocate() returns -EBUSY that is treated specially. Change comparison against zero to make checkpatch.pl happy. Signed-off-by: Serhii Popovych [dwg: Changed BUG_ON()s to WARN_ON()s and altered commit message for clarity] Signed-off-by: David Gibson --- arch/powerpc/kvm/book3s_64_mmu_hv.c | 44 +++++++++++++++++++++++-------------- 1 file changed, 27 insertions(+), 17 deletions(-) diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c index 9660972..31fa710 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -65,11 +65,17 @@ struct kvm_resize_hpt { u32 order; /* These fields protected by kvm->lock */ + + /* Possible values and their usage: + * <0 an error occurred during allocation, + * -EBUSY allocation is in the progress, + * 0 allocation made successfuly. + */ int error; - bool prepare_done; - /* Private to the work thread, until prepare_done is true, - * then protected by kvm->resize_hpt_sem */ + /* Private to the work thread, until error != -EBUSY, + * then protected by kvm->lock. + */ struct kvm_hpt_info hpt; }; @@ -1433,15 +1439,23 @@ static void resize_hpt_prepare_work(struct work_struct *work) struct kvm *kvm = resize->kvm; int err; + if (WARN_ON(resize->error != -EBUSY)) + return; + resize_hpt_debug(resize, "resize_hpt_prepare_work(): order = %d\n", resize->order); err = resize_hpt_allocate(resize); + /* We have strict assumption about -EBUSY + * when preparing for HPT resize. + */ + if (WARN_ON(err == -EBUSY)) + err = -EINPROGRESS; + mutex_lock(&kvm->lock); resize->error = err; - resize->prepare_done = true; mutex_unlock(&kvm->lock); } @@ -1466,14 +1480,12 @@ long kvm_vm_ioctl_resize_hpt_prepare(struct kvm *kvm, if (resize) { if (resize->order == shift) { - /* Suitable resize in progress */ - if (resize->prepare_done) { - ret = resize->error; - if (ret != 0) - resize_hpt_release(kvm, resize); - } else { + /* Suitable resize in progress? */ + ret = resize->error; + if (ret == -EBUSY) ret = 100; /* estimated time in ms */ - } + else if (ret) + resize_hpt_release(kvm, resize); goto out; } @@ -1493,6 +1505,8 @@ long kvm_vm_ioctl_resize_hpt_prepare(struct kvm *kvm, ret = -ENOMEM; goto out; } + + resize->error = -EBUSY; resize->order = shift; resize->kvm = kvm; INIT_WORK(&resize->work, resize_hpt_prepare_work); @@ -1547,16 +1561,12 @@ long kvm_vm_ioctl_resize_hpt_commit(struct kvm *kvm, if (!resize || (resize->order != shift)) goto out; - ret = -EBUSY; - if (!resize->prepare_done) - goto out; - ret = resize->error; - if (ret != 0) + if (ret) goto out; ret = resize_hpt_rehash(resize); - if (ret != 0) + if (ret) goto out; resize_hpt_pivot(resize);