From patchwork Fri Jul 17 12:55:04 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 11670093 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 08E9960D for ; Fri, 17 Jul 2020 12:58:33 +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 D3B59208DB for ; Fri, 17 Jul 2020 12:58:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="FC5smtAY" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D3B59208DB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:52744 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jwPwe-0001LX-0S for patchwork-qemu-devel@patchwork.kernel.org; Fri, 17 Jul 2020 08:58:32 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52164) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jwPtq-0004t8-F2 for qemu-devel@nongnu.org; Fri, 17 Jul 2020 08:55:38 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:50402 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jwPto-0008Nr-QF for qemu-devel@nongnu.org; Fri, 17 Jul 2020 08:55:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1594990536; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=176bmdEuvMrg1lCHTVJS3+4pNrYOIDKZBuVZSCBxM1k=; b=FC5smtAYYnOfkzd+/7itGkCGIi7z2hWmE12e5ntqI3NeZto6Q3FzDUHZyt1K9sEuWT69C5 DmXAVWpbVMooPOBgCpTXIfrI0Krmnx119eJPZOTm+gtBrVGnUAvygXNp5fE65F5yb5J15Q iZCzDbgPRkCeykSRlFPpFIU9d2hucU8= 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-141-gVTc5EiaOy-oG4RMnRGGcw-1; Fri, 17 Jul 2020 08:55:31 -0400 X-MC-Unique: gVTc5EiaOy-oG4RMnRGGcw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id ED9A28C5A8E; Fri, 17 Jul 2020 12:55:24 +0000 (UTC) Received: from linux.fritz.box.com (ovpn-113-80.ams2.redhat.com [10.36.113.80]) by smtp.corp.redhat.com (Postfix) with ESMTP id 05886710C8; Fri, 17 Jul 2020 12:55:23 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Subject: [PULL 06/12] nbd: make nbd_export_close_all() synchronous Date: Fri, 17 Jul 2020 14:55:04 +0200 Message-Id: <20200717125510.238374-7-kwolf@redhat.com> In-Reply-To: <20200717125510.238374-1-kwolf@redhat.com> References: <20200717125510.238374-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=207.211.31.120; envelope-from=kwolf@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/17 03:33:51 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: , Cc: kwolf@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" From: Vladimir Sementsov-Ogievskiy Consider nbd_export_close_all(). The call-stack looks like this: nbd_export_close_all() -> nbd_export_close -> call client_close() for each client. client_close() doesn't guarantee that client is closed: nbd_trip() keeps reference to it. So, nbd_export_close_all() just reduce reference counter on export and removes it from the list, but doesn't guarantee that nbd_trip() finished neither export actually removed. Let's wait for all exports actually removed. Without this fix, the following crash is possible: - export bitmap through internal Qemu NBD server - connect a client - shutdown Qemu On shutdown nbd_export_close_all is called, but it actually don't wait for nbd_trip() to finish and to release its references. So, export is not release, and exported bitmap remains busy, and on try to remove the bitmap (which is part of bdrv_close()) the assertion fails: bdrv_release_dirty_bitmap_locked: Assertion `!bdrv_dirty_bitmap_busy(bitmap)' failed Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Eric Blake Message-Id: <20200714162234.13113-2-vsementsov@virtuozzo.com> Signed-off-by: Kevin Wolf --- nbd/server.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/nbd/server.c b/nbd/server.c index 5357f588f0..4752a6c8bc 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -102,6 +102,8 @@ struct NBDExport { }; static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports); +static QTAILQ_HEAD(, NBDExport) closed_exports = + QTAILQ_HEAD_INITIALIZER(closed_exports); /* NBDExportMetaContexts represents a list of contexts to be exported, * as selected by NBD_OPT_SET_META_CONTEXT. Also used for @@ -1659,6 +1661,7 @@ void nbd_export_close(NBDExport *exp) g_free(exp->name); exp->name = NULL; QTAILQ_REMOVE(&exports, exp, next); + QTAILQ_INSERT_TAIL(&closed_exports, exp, next); } g_free(exp->description); exp->description = NULL; @@ -1722,7 +1725,9 @@ void nbd_export_put(NBDExport *exp) g_free(exp->export_bitmap_context); } + QTAILQ_REMOVE(&closed_exports, exp, next); g_free(exp); + aio_wait_kick(); } } @@ -1742,6 +1747,9 @@ void nbd_export_close_all(void) nbd_export_close(exp); aio_context_release(aio_context); } + + AIO_WAIT_WHILE(NULL, !(QTAILQ_EMPTY(&exports) && + QTAILQ_EMPTY(&closed_exports))); } static int coroutine_fn nbd_co_send_iov(NBDClient *client, struct iovec *iov,