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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 53E17C32751 for ; Wed, 31 Jul 2019 14:44:05 +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 2B72220659 for ; Wed, 31 Jul 2019 14:44:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2B72220659 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:41473 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hsppk-0002Tt-8h for qemu-devel@archiver.kernel.org; Wed, 31 Jul 2019 10:44:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44752) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hspp5-0001CN-4J for qemu-devel@nongnu.org; Wed, 31 Jul 2019 10:43:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hspp4-0000vL-1w for qemu-devel@nongnu.org; Wed, 31 Jul 2019 10:43:23 -0400 Received: from mga05.intel.com ([192.55.52.43]:51112) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hspp3-0000sd-OI for qemu-devel@nongnu.org; Wed, 31 Jul 2019 10:43:22 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 31 Jul 2019 07:43:18 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,330,1559545200"; d="scan'208";a="347557230" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by orsmga005.jf.intel.com with ESMTP; 31 Jul 2019 07:43:17 -0700 From: Wei Yang To: qemu-devel@nongnu.org Date: Wed, 31 Jul 2019 22:42:25 +0800 Message-Id: <20190731144225.3784-3-richardw.yang@linux.intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190731144225.3784-1-richardw.yang@linux.intel.com> References: <20190731144225.3784-1-richardw.yang@linux.intel.com> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 192.55.52.43 Subject: [Qemu-devel] [PATCH 2/2] migration/qemu-file: fix potential buf waste for extra buf_index adjustment 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: Wei Yang , dgilbert@redhat.com, quintela@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" In add_to_iovec(), qemu_fflush() will be called if iovec is full. If this happens, buf_index is reset. Currently, this is not checked and buf_index would always been adjust with buf size. This is not harmful, but will waste some space in file buffer. This patch make add_to_iovec() return 1 when it has flushed the file. Then the caller could check the return value to see whether it is necessary to adjust the buf_index any more. Signed-off-by: Wei Yang --- migration/qemu-file.c | 42 ++++++++++++++++++++++++++++-------------- 1 file changed, 28 insertions(+), 14 deletions(-) diff --git a/migration/qemu-file.c b/migration/qemu-file.c index 35c22605dd..05d9f42ddb 100644 --- a/migration/qemu-file.c +++ b/migration/qemu-file.c @@ -343,8 +343,16 @@ int qemu_fclose(QEMUFile *f) return ret; } -static void add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size, - bool may_free) +/* + * Add buf to iovec. Do flush if iovec is full. + * + * Return values: + * 1 iovec is full and flushed + * 0 iovec is not flushed + * + */ +static int add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size, + bool may_free) { /* check for adjacent buffer and coalesce them */ if (f->iovcnt > 0 && buf == f->iov[f->iovcnt - 1].iov_base + @@ -362,7 +370,10 @@ static void add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size, if (f->iovcnt >= MAX_IOV_SIZE) { qemu_fflush(f); + return 1; } + + return 0; } void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, size_t size, @@ -391,10 +402,11 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, size_t size) } memcpy(f->buf + f->buf_index, buf, l); f->bytes_xfer += l; - add_to_iovec(f, f->buf + f->buf_index, l, false); - f->buf_index += l; - if (f->buf_index == IO_BUF_SIZE) { - qemu_fflush(f); + if (!add_to_iovec(f, f->buf + f->buf_index, l, false)) { + f->buf_index += l; + if (f->buf_index == IO_BUF_SIZE) { + qemu_fflush(f); + } } if (qemu_file_get_error(f)) { break; @@ -412,10 +424,11 @@ void qemu_put_byte(QEMUFile *f, int v) f->buf[f->buf_index] = v; f->bytes_xfer++; - add_to_iovec(f, f->buf + f->buf_index, 1, false); - f->buf_index++; - if (f->buf_index == IO_BUF_SIZE) { - qemu_fflush(f); + if (!add_to_iovec(f, f->buf + f->buf_index, 1, false)) { + f->buf_index++; + if (f->buf_index == IO_BUF_SIZE) { + qemu_fflush(f); + } } } @@ -717,10 +730,11 @@ ssize_t qemu_put_compression_data(QEMUFile *f, z_stream *stream, } qemu_put_be32(f, blen); - add_to_iovec(f, f->buf + f->buf_index, blen, false); - f->buf_index += blen; - if (f->buf_index == IO_BUF_SIZE) { - qemu_fflush(f); + if (!add_to_iovec(f, f->buf + f->buf_index, blen, false)) { + f->buf_index += blen; + if (f->buf_index == IO_BUF_SIZE) { + qemu_fflush(f); + } } return blen + sizeof(int32_t); } -- 2.17.1