From patchwork Fri Feb 26 15:10:06 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= X-Patchwork-Id: 8438041 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 56F2E9F2F0 for ; Fri, 26 Feb 2016 15:11:02 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id AEB39203B1 for ; Fri, 26 Feb 2016 15:11:01 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EB73B203B0 for ; Fri, 26 Feb 2016 15:11:00 +0000 (UTC) Received: from localhost ([::1]:50336 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aZK2m-00089z-7l for patchwork-qemu-devel@patchwork.kernel.org; Fri, 26 Feb 2016 10:11:00 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34578) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aZK2U-00086y-Cv for qemu-devel@nongnu.org; Fri, 26 Feb 2016 10:10:43 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aZK2T-0002i1-6I for qemu-devel@nongnu.org; Fri, 26 Feb 2016 10:10:42 -0500 Received: from mx1.redhat.com ([209.132.183.28]:52899) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aZK2S-0002hp-Qk for qemu-devel@nongnu.org; Fri, 26 Feb 2016 10:10:41 -0500 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (Postfix) with ESMTPS id 8D93A935D8 for ; Fri, 26 Feb 2016 15:10:40 +0000 (UTC) Received: from t530wlan.home.berrange.com.com (vpn1-4-93.ams2.redhat.com [10.36.4.93]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u1QFAYD6017253; Fri, 26 Feb 2016 10:10:39 -0500 From: "Daniel P. Berrange" To: qemu-devel@nongnu.org Date: Fri, 26 Feb 2016 15:10:06 +0000 Message-Id: <1456499430-8558-4-git-send-email-berrange@redhat.com> In-Reply-To: <1456499430-8558-1-git-send-email-berrange@redhat.com> References: <1456499430-8558-1-git-send-email-berrange@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: Amit Shah , "Dr. David Alan Gilbert" , Juan Quintela Subject: [Qemu-devel] [PATCH v3 03/27] migration: ensure qemu_fflush() always writes full data amount X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The QEMUFile writev_buffer / put_buffer functions are expected to write out the full set of requested data, blocking until complete. The qemu_fflush() caller does not expect to deal with partial writes. Clarify the function comments and add a sanity check to the code to catch mistaken implementations. Reviewed-by: Dr. David Alan Gilbert Signed-off-by: Daniel P. Berrange --- include/migration/qemu-file.h | 6 ++++-- migration/qemu-file.c | 16 ++++++++++++---- 2 files changed, 16 insertions(+), 6 deletions(-) diff --git a/include/migration/qemu-file.h b/include/migration/qemu-file.h index 3f6b4ed..5909ff0 100644 --- a/include/migration/qemu-file.h +++ b/include/migration/qemu-file.h @@ -28,7 +28,8 @@ /* This function writes a chunk of data to a file at the given position. * The pos argument can be ignored if the file is only being used for - * streaming. The handler should try to write all of the data it can. + * streaming. The handler must write all of the data or return a negative + * errno value. */ typedef ssize_t (QEMUFilePutBufferFunc)(void *opaque, const uint8_t *buf, int64_t pos, size_t size); @@ -54,7 +55,8 @@ typedef int (QEMUFileCloseFunc)(void *opaque); typedef int (QEMUFileGetFD)(void *opaque); /* - * This function writes an iovec to file. + * This function writes an iovec to file. The handler must write all + * of the data or return a negative errno value. */ typedef ssize_t (QEMUFileWritevBufferFunc)(void *opaque, struct iovec *iov, int iovcnt, int64_t pos); diff --git a/migration/qemu-file.c b/migration/qemu-file.c index 6f4a129..656db4a 100644 --- a/migration/qemu-file.c +++ b/migration/qemu-file.c @@ -108,11 +108,13 @@ bool qemu_file_is_writable(QEMUFile *f) * Flushes QEMUFile buffer * * If there is writev_buffer QEMUFileOps it uses it otherwise uses - * put_buffer ops. + * put_buffer ops. This will flush all pending data. If data was + * only partially flushed, it will set an error state. */ void qemu_fflush(QEMUFile *f) { ssize_t ret = 0; + ssize_t expect = 0; if (!qemu_file_is_writable(f)) { return; @@ -120,21 +122,27 @@ void qemu_fflush(QEMUFile *f) if (f->ops->writev_buffer) { if (f->iovcnt > 0) { + expect = iov_size(f->iov, f->iovcnt); ret = f->ops->writev_buffer(f->opaque, f->iov, f->iovcnt, f->pos); } } else { if (f->buf_index > 0) { + expect = f->buf_index; ret = f->ops->put_buffer(f->opaque, f->buf, f->pos, f->buf_index); } } + if (ret >= 0) { f->pos += ret; } + /* We expect the QEMUFile write impl to send the full + * data set we requested, so sanity check that. + */ + if (ret != expect) { + qemu_file_set_error(f, ret < 0 ? ret : -EIO); + } f->buf_index = 0; f->iovcnt = 0; - if (ret < 0) { - qemu_file_set_error(f, ret); - } } void ram_control_before_iterate(QEMUFile *f, uint64_t flags)