From patchwork Tue Sep 6 13:56:03 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: 9317075 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id B1CF2607D3 for ; Tue, 6 Sep 2016 14:19:16 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B228D28D10 for ; Tue, 6 Sep 2016 14:19:16 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A6F5528D33; Tue, 6 Sep 2016 14:19:16 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 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.wl.linuxfoundation.org (Postfix) with ESMTPS id 4EE2328D10 for ; Tue, 6 Sep 2016 14:19:16 +0000 (UTC) Received: from localhost ([::1]:33809 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bhHDX-0006fo-CN for patchwork-qemu-devel@patchwork.kernel.org; Tue, 06 Sep 2016 10:19:15 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37598) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bhGrI-0004F9-Et for qemu-devel@nongnu.org; Tue, 06 Sep 2016 09:56:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bhGrH-0006BH-Hz for qemu-devel@nongnu.org; Tue, 06 Sep 2016 09:56:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49406) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bhGrH-0006B7-Bt for qemu-devel@nongnu.org; Tue, 06 Sep 2016 09:56:15 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E21B3C0567A3 for ; Tue, 6 Sep 2016 13:56:14 +0000 (UTC) Received: from t530wlan.home.berrange.com.com (vpn1-6-152.ams2.redhat.com [10.36.6.152]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u86DuBkT009987; Tue, 6 Sep 2016 09:56:14 -0400 From: "Daniel P. Berrange" To: qemu-devel@nongnu.org Date: Tue, 6 Sep 2016 14:56:03 +0100 Message-Id: <1473170165-540-3-git-send-email-berrange@redhat.com> In-Reply-To: <1473170165-540-1-git-send-email-berrange@redhat.com> References: <1473170165-540-1-git-send-email-berrange@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Tue, 06 Sep 2016 13:56:14 +0000 (UTC) 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] [PATCH v2 2/4] sclpconsolelm: remove bogus check for -EAGAIN X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paolo Bonzini Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP The write_console_data() method in sclpconsole-lm.c checks whether the return value of qemu_chr_fe_write() has the value of -EAGAIN and if so then increments the buffer offset by the value of EAGAIN. Fortunately qemu_chr_fe_write() will never return EAGAIN directly, rather it returns -1 with errno set to EAGAIN, so this broken code path was not reachable. The behaviour on EAGAIN was stil bad though, causing the write_console_data() to busy_wait repeatedly calling qemu_chr_fe_write() with no sleep between iters. Just remove all this loop logic and replace with a call to qemu_chr_fe_write_all(). Acked-by: Cornelia Huck Signed-off-by: Daniel P. Berrange --- hw/char/sclpconsole-lm.c | 18 +++--------------- 1 file changed, 3 insertions(+), 15 deletions(-) diff --git a/hw/char/sclpconsole-lm.c b/hw/char/sclpconsole-lm.c index a22ad8d..8cb0026 100644 --- a/hw/char/sclpconsole-lm.c +++ b/hw/char/sclpconsole-lm.c @@ -201,21 +201,9 @@ static int write_console_data(SCLPEvent *event, const uint8_t *buf, int len) return len; } - buf_offset = buf; - while (len > 0) { - ret = qemu_chr_fe_write(scon->chr, buf, len); - if (ret == 0) { - /* a pty doesn't seem to be connected - no error */ - len = 0; - } else if (ret == -EAGAIN || (ret > 0 && ret < len)) { - len -= ret; - buf_offset += ret; - } else { - len = 0; - } - } - - return ret; + /* XXX this blocks entire thread. Rewrite to use + * qemu_chr_fe_write and background I/O callbacks */ + return qemu_chr_fe_write_all(scon->chr, buf, len); } static int process_mdb(SCLPEvent *event, MDBO *mdbo)