From patchwork Thu Apr 8 15:59:08 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Emanuele Giuseppe Esposito X-Patchwork-Id: 1463898 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; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=FjH/Uzs3; 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 4FGQvW2WZLz9sX1 for ; Fri, 9 Apr 2021 02:00:07 +1000 (AEST) Received: from localhost ([::1]:36872 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lUX4f-0002ja-5h for incoming@patchwork.ozlabs.org; Thu, 08 Apr 2021 12:00:05 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40708) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lUX41-0002gy-76 for qemu-devel@nongnu.org; Thu, 08 Apr 2021 11:59:25 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:39181) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lUX3y-0006ro-MV for qemu-devel@nongnu.org; Thu, 08 Apr 2021 11:59:24 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1617897561; 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; bh=6nVQM9KSbB5wNBR62KPFq+xx6HkOuLewm+uCVTwrcew=; b=FjH/Uzs3RvL3GY+x3r+64VPWKqjfx7ZE+3bRdRB4mZbMLUHdoGrzMbjzSOe0gPLzhTWhU7 Inqkgn85azYTkMK6tyRzFZxBB4d0bAzTmc749+BXJaEf3eU+iVVteM3LCOje5saiiWgWoS YFmU7GDqlKEyHzbPSznCrny7yyfKHNw= 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-476-KYX5rnj8OhqH_Zd-1I0X_g-1; Thu, 08 Apr 2021 11:59:19 -0400 X-MC-Unique: KYX5rnj8OhqH_Zd-1I0X_g-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 324631020C28; Thu, 8 Apr 2021 15:59:18 +0000 (UTC) Received: from localhost.localdomain.com (ovpn-113-155.ams2.redhat.com [10.36.113.155]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3DE005D6AC; Thu, 8 Apr 2021 15:59:15 +0000 (UTC) From: Emanuele Giuseppe Esposito To: qemu-block@nongnu.org Subject: [PATCH 0/5] blkdebug: fix racing condition when iterating on Date: Thu, 8 Apr 2021 17:59:08 +0200 Message-Id: <20210408155913.53235-1-eesposit@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eesposit@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=170.10.133.124; envelope-from=eesposit@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-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: , Cc: Kevin Wolf , Paolo Bonzini , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" When qemu_coroutine_enter is executed in a loop (even QEMU_FOREACH_SAFE), the new routine can modify the list, for example removing an element, causing problem when control is given back to the caller that continues iterating on the same list. Patch 1 solves the issue in blkdebug_debug_resume by restarting the list walk after every coroutine_enter if list has to be fully iterated. Patches 2,3,4 aim to fix blkdebug_debug_event by gathering all actions that the rules make in a counter and invoking the respective coroutine_yeld only after processing all requests. Patch 5 adds a lock to protect rules and suspended_reqs. Signed-off-by: Emanuele Giuseppe Esposito Emanuele Giuseppe Esposito (5): blkdebug: refactor removal of a suspended request blkdebug: move post-resume handling to resume_req_by_tag blkdebug: track all actions blkdebug: do not suspend in the middle of QLIST_FOREACH_SAFE blkdebug: protect rules and suspended_reqs with a lock block/blkdebug.c | 113 +++++++++++++++++++++++++++++++++-------------- 1 file changed, 79 insertions(+), 34 deletions(-)