From patchwork Thu Sep 24 09:22:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 272865 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=-9.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 065EFC2D0E2 for ; Thu, 24 Sep 2020 09:59:09 +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 5796E21D91 for ; Thu, 24 Sep 2020 09:59:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="MuJeVA2p" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5796E21D91 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+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:37522 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kLO1r-00015D-ES for qemu-devel@archiver.kernel.org; Thu, 24 Sep 2020 05:59:07 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39382) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kLNU9-00020h-65 for qemu-devel@nongnu.org; Thu, 24 Sep 2020 05:24:17 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:35546) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kLNU7-0006A6-8U for qemu-devel@nongnu.org; Thu, 24 Sep 2020 05:24:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600939454; 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=yYD3ca9nKAPeS67sQ64Xwoz3V+LQEik3mZArxHhunnU=; b=MuJeVA2p/2L1+rKUZkNO2Av8jhPVCLjiuJJDLMmX74XXBDT2/efR51erdwe1+zKViwHCFC UxNzxaUXO1Ltvn8LzoBtaAn7s9HZqjxWH9ElCioYQj/Q6B1hKjgotfJZs1YJ/8C0kvc5XY Z1XWIKCqWehZfkUEEMFEoDGn1yqtmQk= 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-346-VJM2flinNBusWbiB7EqsTg-1; Thu, 24 Sep 2020 05:24:10 -0400 X-MC-Unique: VJM2flinNBusWbiB7EqsTg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id ACF441007464 for ; Thu, 24 Sep 2020 09:24:09 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id D1C626198C; Thu, 24 Sep 2020 09:24:04 +0000 (UTC) From: Paolo Bonzini To: qemu-devel@nongnu.org Subject: [PULL 65/92] char: fix logging when chardev write fails Date: Thu, 24 Sep 2020 05:22:47 -0400 Message-Id: <20200924092314.1722645-66-pbonzini@redhat.com> In-Reply-To: <20200924092314.1722645-1-pbonzini@redhat.com> References: <20200924092314.1722645-1-pbonzini@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=63.128.21.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/24 01:10:00 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -32 X-Spam_score: -3.3 X-Spam_bar: --- X-Spam_report: (-3.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.228, 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_H5=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: =?utf-8?q?Marc-Andr=C3=A9_Lureau?= , =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Daniel P. Berrangé The qemu_chr_write_buffer() method sends data to the chardev backend for writing, and then also writes to the log file. In case the chardev backend only writes part of the data buffer, we need to make sure we only log the same subset. qemu_chr_write_buffer() will be invoked again later to write the rest of the buffer. In the case the chardev backend returns an error though, no further attempts to likely to be made to write the data. We must therefore write the entire buffer to the log immediately. An example where this is important is with the socket backend. This will return -1 for all writes if no client is currently connected. We still wish to write data to the log file when no client is present though. This used to work because the chardev would return "len" to pretend it had written all data when no client is connected, but this changed to return an error in commit 271094474b65de1ad7aaf729938de3d9b9d0d36f Author: Dima Stepanov Date: Thu May 28 12:11:18 2020 +0300 char-socket: return -1 in case of disconnect during tcp_chr_write and this broke the logging, resulting in all data being discarded when no client is present. Fixes: https://bugs.launchpad.net/qemu/+bug/1893691 Signed-off-by: Daniel P. Berrangé Reviewed-by: Marc-André Lureau Signed-off-by: Paolo Bonzini --- chardev/char.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/chardev/char.c b/chardev/char.c index 6b85099c03..78553125d3 100644 --- a/chardev/char.c +++ b/chardev/char.c @@ -138,7 +138,20 @@ static int qemu_chr_write_buffer(Chardev *s, } } if (*offset > 0) { + /* + * If some data was written by backend, we should + * only log what was actually written. This method + * may be invoked again to write the remaining + * method, thus we'll log the remainder at that time. + */ qemu_chr_write_log(s, buf, *offset); + } else if (res < 0) { + /* + * If a fatal error was reported by the backend, + * assume this method won't be invoked again with + * this buffer, so log it all right away. + */ + qemu_chr_write_log(s, buf, len); } qemu_mutex_unlock(&s->chr_write_lock);