From nobody Wed Nov 12 05:28:11 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1568298634; cv=none; d=zoho.com; s=zohoarc; b=g8MYT6DJuH+AocYoqf4JiE6+eg56nz4rrZn6DezS3K890nSWOJXHMu+qVllNpBIYLbLuVWf+XwcRQEHlB4fne//iq4aSIQzw1Hf8xhzdcup3ZE4fOVntoqnTVfi6cto2VS/iG1pEUFCxlQVzJJ9NAhucH2qlvkrrPHrzD2Gqv9o= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1568298634; h=Content-Transfer-Encoding:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To:ARC-Authentication-Results; bh=0fVuvl50t/eGwzAh64u1EdOBoo2uHNtI0lSPtacIML0=; b=bSw7XFffEWK3F9RJpiTD2SzO4zLEoTeKpVVb97EtoW9ufRAu8GcVIwTkgUHGKfZt0yZ99ADtAj5X7zdu1ZrSzD84mihpaeaUNcPPCdEKDkZAMsTi6PT5DBk0G+iRayGTi5KJ4JhExovf2QxetI0fdMwbaAjmoMbVHUoxDwHHIcM= ARC-Authentication-Results: i=1; mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1568298634162729.5262959228625; Thu, 12 Sep 2019 07:30:34 -0700 (PDT) Received: from localhost ([::1]:35198 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i8Q7E-0001io-Cf for importer@patchew.org; Thu, 12 Sep 2019 10:30:32 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40657) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i8PUy-0007Ky-HI for qemu-devel@nongnu.org; Thu, 12 Sep 2019 09:51:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i8PUx-0003Hq-CG for qemu-devel@nongnu.org; Thu, 12 Sep 2019 09:51:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60981) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i8PUx-0003HN-4f for qemu-devel@nongnu.org; Thu, 12 Sep 2019 09:50:59 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id 72DAC190C006; Thu, 12 Sep 2019 13:50:58 +0000 (UTC) Received: from dgilbert-t580.localhost (unknown [10.36.118.12]) by smtp.corp.redhat.com (Postfix) with ESMTP id 21E445D704; Thu, 12 Sep 2019 13:50:56 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, ivanren@tencent.com, peterx@redhat.com, richardw.yang@linux.intel.com, yury-kotov@yandex-team.ru, quintela@redhat.com Date: Thu, 12 Sep 2019 14:50:05 +0100 Message-Id: <20190912135006.14820-12-dgilbert@redhat.com> In-Reply-To: <20190912135006.14820-1-dgilbert@redhat.com> References: <20190912135006.14820-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.70]); Thu, 12 Sep 2019 13:50:58 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 11/12] 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: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" From: Wei Yang 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 Reviewed-by: Dr. David Alan Gilbert Message-Id: <20190911132839.23336-3-richard.weiyang@gmail.com> Signed-off-by: Dr. David Alan Gilbert --- migration/qemu-file.c | 43 ++++++++++++++++++++++++++----------------- 1 file changed, 26 insertions(+), 17 deletions(-) diff --git a/migration/qemu-file.c b/migration/qemu-file.c index 66627088d4..26fb25ddc1 100644 --- a/migration/qemu-file.c +++ b/migration/qemu-file.c @@ -381,8 +381,16 @@ int qemu_fclose(QEMUFile *f) return ret; } =20 -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 =3D=3D f->iov[f->iovcnt - 1].iov_base + @@ -400,6 +408,19 @@ static void add_to_iovec(QEMUFile *f, const uint8_t *b= uf, size_t size, =20 if (f->iovcnt >=3D MAX_IOV_SIZE) { qemu_fflush(f); + return 1; + } + + return 0; +} + +static void add_buf_to_iovec(QEMUFile *f, size_t len) +{ + if (!add_to_iovec(f, f->buf + f->buf_index, len, false)) { + f->buf_index +=3D len; + if (f->buf_index =3D=3D IO_BUF_SIZE) { + qemu_fflush(f); + } } } =20 @@ -429,11 +450,7 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, = size_t size) } memcpy(f->buf + f->buf_index, buf, l); f->bytes_xfer +=3D l; - add_to_iovec(f, f->buf + f->buf_index, l, false); - f->buf_index +=3D l; - if (f->buf_index =3D=3D IO_BUF_SIZE) { - qemu_fflush(f); - } + add_buf_to_iovec(f, l); if (qemu_file_get_error(f)) { break; } @@ -450,11 +467,7 @@ void qemu_put_byte(QEMUFile *f, int v) =20 f->buf[f->buf_index] =3D v; f->bytes_xfer++; - add_to_iovec(f, f->buf + f->buf_index, 1, false); - f->buf_index++; - if (f->buf_index =3D=3D IO_BUF_SIZE) { - qemu_fflush(f); - } + add_buf_to_iovec(f, 1); } =20 void qemu_file_skip(QEMUFile *f, int size) @@ -760,11 +773,7 @@ ssize_t qemu_put_compression_data(QEMUFile *f, z_strea= m *stream, } =20 qemu_put_be32(f, blen); - add_to_iovec(f, f->buf + f->buf_index, blen, false); - f->buf_index +=3D blen; - if (f->buf_index =3D=3D IO_BUF_SIZE) { - qemu_fflush(f); - } + add_buf_to_iovec(f, blen); return blen + sizeof(int32_t); } =20 --=20 2.21.0