From patchwork Mon Jul 6 21:14:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Duyck X-Patchwork-Id: 1323970 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=BAjdhT1H; dkim-atps=neutral Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4B0yy15V4fz9sRN for ; Tue, 7 Jul 2020 07:14:49 +1000 (AEST) Received: from localhost ([::1]:59312 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jsYRr-0006qg-0w for incoming@patchwork.ozlabs.org; Mon, 06 Jul 2020 17:14:47 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60484) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jsYRJ-0006oP-5K for qemu-devel@nongnu.org; Mon, 06 Jul 2020 17:14:13 -0400 Received: from mail-pl1-x644.google.com ([2607:f8b0:4864:20::644]:34421) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jsYRH-0000HF-89 for qemu-devel@nongnu.org; Mon, 06 Jul 2020 17:14:12 -0400 Received: by mail-pl1-x644.google.com with SMTP id o1so9253230plk.1 for ; Mon, 06 Jul 2020 14:14:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:from:to:cc:date:message-id:in-reply-to:references :user-agent:mime-version:content-transfer-encoding; bh=uMeY2M7/mS/0n1w9o0LfcRh5FR+KNB3RWjicNkUWe8A=; b=BAjdhT1Hj7d1jWsXXdDMb/DFYgBg6VUnvd9jGpOujAnNH5rNO4phu2cxMLwdHjmfhU ul9ud4S7DRBm5pZ4HUSMylrSSDAYNO6JvmXY93so/aZyVvA36aNZXtaNE6FcjH47qgoX JeKCqjNYmhyLTBTARFm1lNQIFMSmklvma062taCg2uCuzS3FoBISQ5ofzize4vDEiY/H X3mVETwbl9HIMDYH++na2QnWftpragMnsj1J3KZS5pDbFFDoW98xQ56Ab53up3e+PX9u pwL3t1khkbenifVvuVhR3vqmKm+Lx3iv2hIGKRl6Gf1Mp/s0iG4fxYHj0Ov7MdWtzUq3 t34Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:date:message-id:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=uMeY2M7/mS/0n1w9o0LfcRh5FR+KNB3RWjicNkUWe8A=; b=InWkS6auqE2ZKNAZGgWtHy+6zbSwVfZ4wMoX2guYngq01Sfb6BYwAvDUA9VhiLET82 iOGCMyrILMwmFUzgpnUFCUfqgmPlIYWr8jI/ZDYo5HieTsS7QTHrauD3MoQR9LZDkdmY ajYOhp64vSEScllKSBa3VncJvWGlWJxmXT8Z4yP8q+zNdXzWt8ZvitbscQSmsofUw4xU dTBjL5kYh1ZX+g2ouHDhCP9nToxKBxjRaClvYRgn7epP3y1bFJ8H/V9B2CyNcws9QWty Xi74ZtE2y8Md3LWcMZstvcF9mYfNqjj0c9fSgEEcPwIVC98iqV4lXvvFGFfy37UMmpuQ 0pvg== X-Gm-Message-State: AOAM531TT1ffjFvY6z1o1+6Y2QP1v4AJtQEWl89ZzG6882joMsneGa0R 8Y+P4+/biCrtJr48vfxs9SQ= X-Google-Smtp-Source: ABdhPJxeOxhLlr8JHQ4IBGLFjw5G3q/E2zn5t9OnC1a/HRP/HxgxSIgooJOifd1hle4T/+1RIHiq4w== X-Received: by 2002:a17:90a:e7cd:: with SMTP id kb13mr1016385pjb.138.1594070048882; Mon, 06 Jul 2020 14:14:08 -0700 (PDT) Received: from localhost.localdomain ([2001:470:b:9c3:9e5c:8eff:fe4f:f2d0]) by smtp.gmail.com with ESMTPSA id v28sm20397808pgc.44.2020.07.06.14.14.08 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 06 Jul 2020 14:14:08 -0700 (PDT) Subject: [PATCH v2 2/3] virtio-balloon: Add locking to prevent possible race when starting hinting From: Alexander Duyck To: david@redhat.com, mst@redhat.com Date: Mon, 06 Jul 2020 14:14:07 -0700 Message-ID: <20200706211407.20018.51061.stgit@localhost.localdomain> In-Reply-To: <20200706211314.20018.89695.stgit@localhost.localdomain> References: <20200706211314.20018.89695.stgit@localhost.localdomain> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::644; envelope-from=alexander.duyck@gmail.com; helo=mail-pl1-x644.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: virtio-dev@lists.oasis-open.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: Alexander Duyck There is already locking in place when we are stopping free page hinting but there is not similar protections in place when we start. I can only assume this was overlooked as in most cases the page hinting should not be occurring when we are starting the hinting, however there is still a chance we could be processing hints by the time we get back around to restarting the hinting so we are better off making sure to protect the state with the mutex lock rather than just updating the value with no protections. Signed-off-by: Alexander Duyck Acked-by: David Hildenbrand --- hw/virtio/virtio-balloon.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index 0c0fd7114799..b3e96a822b4d 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -593,6 +593,8 @@ static void virtio_balloon_free_page_start(VirtIOBalloon *s) return; } + qemu_mutex_lock(&s->free_page_lock); + if (s->free_page_report_cmd_id == UINT_MAX) { s->free_page_report_cmd_id = VIRTIO_BALLOON_FREE_PAGE_REPORT_CMD_ID_MIN; @@ -601,6 +603,8 @@ static void virtio_balloon_free_page_start(VirtIOBalloon *s) } s->free_page_report_status = FREE_PAGE_REPORT_S_REQUESTED; + qemu_mutex_unlock(&s->free_page_lock); + virtio_notify_config(vdev); }