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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 6C4C4C433C1 for ; Tue, 23 Mar 2021 12:06:15 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id D020E61994 for ; Tue, 23 Mar 2021 12:06:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D020E61994 Authentication-Results: mail.kernel.org; dmarc=pass (p=none dis=none) header.from=nongnu.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:54568 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lOfnZ-00034i-Nc for qemu-devel@archiver.kernel.org; Tue, 23 Mar 2021 08:06:13 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36818) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lOfmP-0001xQ-UR for qemu-devel@nongnu.org; Tue, 23 Mar 2021 08:05:01 -0400 Received: from esa3.hc3370-68.iphmx.com ([216.71.145.155]:64783) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lOfmO-0001sG-6c for qemu-devel@nongnu.org; Tue, 23 Mar 2021 08:05:01 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=citrix.com; s=securemail; t=1616501100; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=KuQPw6F+xqG73m8XTxaXL/LTNGMUBj+pjwi+99q8ME0=; b=RGfJyYWRJpJ0hpQ7UAAIdr+LG1kH0/Nh7dWxDr5VSMQcpjgKy1f6WKvd +BMR43wCDzDK0dRkLy9N5QJhYE3SBY0R4PTa63kZRrG7ygTMksPfBmSyS hDnKl2oIsMnX9XRizMoWnczdKFMu9R743R0xc5NzKoFEydJrsa5OVBgye 0=; Authentication-Results: esa3.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none IronPort-SDR: np3kepIf5+qKdnWysahK4mMXDIIXh9kY+5RNTQ8aI8PVu+deAKGr0p8mBhwJBW2DSh79fN0Qaw QjA/oJuWDGR2gkQMo3zrLiKZB61gGUTOCrVXODPuCQikx2cVcjcfoQRAzXZvrCrn+P/CiGOAFa XI4KvSGpspavi7epXsyOTT0hjINX1O+fRQ+K3+/Vjchzv1p6R/9EogkBKkuPfoGOKo5v5HwlkD LBIKrO+TqraPdhe2VyhjuEXlkFPbeT5DDUeJf0BZlH20r8P4vXAsSqWBq9yQjivq2Li62aUH3f PGc= X-SBRS: 5.1 X-MesageID: 39891529 X-Ironport-Server: esa3.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED IronPort-HdrOrdr: A9a23:W/KqdKsKavuNzDGN6AFKn/sM7skD89V00zAX/kB9WHVpW+az/v rBoN0w0xjohDENHEw6kdebN6WaBV/a/5h54Y4eVI3SOjXOkm2uMY1k8M/e0yTtcheOjtJ1+K 98f8FFaOHYIkN9ia/BjDWQM9Fl+9Wf9bDtuOG29QYJcShPS4VNqzh0ERyaFEoefnggObMcGI CH7sRK4xqMEE5nDfiTPXUOU+jdq9CjrvuPCnRqOzcd5AaDlj+u4rLheiLouis2aD9T3awktV HMjg2R3NTbj9iA1hTe22XPhq42pPLdzLJ4a/Cku4wwIjXohh3AXvUCZ4G/ X-IronPort-AV: E=Sophos;i="5.81,271,1610427600"; d="scan'208";a="39891529" To: CC: Peter Maydell , Anthony PERARD Subject: [PULL 1/1] xen-block: Fix removal of backend instance via xenstore Date: Tue, 23 Mar 2021 12:04:39 +0000 Message-ID: <20210323120439.563855-2-anthony.perard@citrix.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20210323120439.563855-1-anthony.perard@citrix.com> References: <20210323120439.563855-1-anthony.perard@citrix.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain Received-SPF: pass client-ip=216.71.145.155; envelope-from=anthony.perard@citrix.com; helo=esa3.hc3370-68.iphmx.com X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_PASS=-0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Reply-to: Anthony PERARD From: Anthony PERARD via Whenever a Xen block device is detach via xenstore, the image associated with it remained open by the backend QEMU and an error is logged: qemu-system-i386: failed to destroy drive: Node xvdz-qcow2 is in use This happened since object_unparent() doesn't immediately frees the object and thus keep a reference to the node we are trying to free. The reference is hold by the "drive" property and the call xen_block_drive_destroy() fails. In order to fix that, we call drain_call_rcu() to run the callback setup by bus_remove_child() via object_unparent(). Fixes: 2d24a6466154 ("device-core: use RCU for list of children of a bus") Signed-off-by: Anthony PERARD Reviewed-by: Paul Durrant Message-Id: <20210308143232.83388-1-anthony.perard@citrix.com> --- hw/block/xen-block.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/hw/block/xen-block.c b/hw/block/xen-block.c index ac82d5406337..83754a434481 100644 --- a/hw/block/xen-block.c +++ b/hw/block/xen-block.c @@ -972,6 +972,15 @@ static void xen_block_device_destroy(XenBackendInstance *backend, object_unparent(OBJECT(xendev)); + /* + * Drain all pending RCU callbacks as object_unparent() frees `xendev' + * in a RCU callback. + * And due to the property "drive" still existing in `xendev', we + * can't destroy the XenBlockDrive associated with `xendev' with + * xen_block_drive_destroy() below. + */ + drain_call_rcu(); + if (iothread) { xen_block_iothread_destroy(iothread, errp); if (*errp) { -- Anthony PERARD