From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by 10.25.21.156 with SMTP id 28csp832045lfv; Wed, 3 Aug 2016 09:31:56 -0700 (PDT) X-Received: by 10.200.57.108 with SMTP id t41mr887009qtb.33.1470241916659; Wed, 03 Aug 2016 09:31:56 -0700 (PDT) Return-Path: Received: from lists.gnu.org (lists.gnu.org. [2001:4830:134:3::11]) by mx.google.com with ESMTPS id l3si2656395qkf.79.2016.08.03.09.31.56 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 03 Aug 2016 09:31:56 -0700 (PDT) Received-SPF: pass (google.com: domain of qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org designates 2001:4830:134:3::11 as permitted sender) client-ip=2001:4830:134:3::11; Authentication-Results: mx.google.com; spf=pass (google.com: domain of qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org designates 2001:4830:134:3::11 as permitted sender) smtp.mailfrom=qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org Received: from localhost ([::1]:35716 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bUz5H-0004BQ-Uf for alex.bennee@linaro.org; Wed, 03 Aug 2016 12:31:55 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35868) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bUywu-0004DK-5J for qemu-devel@nongnu.org; Wed, 03 Aug 2016 12:23:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bUywp-0006jC-Hi for qemu-devel@nongnu.org; Wed, 03 Aug 2016 12:23:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33630) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bUywf-0006fs-Ph; Wed, 03 Aug 2016 12:23:01 -0400 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (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 55F2B478; Wed, 3 Aug 2016 16:23:00 +0000 (UTC) Received: from t530wlan.home.berrange.com.com (vpn1-7-219.ams2.redhat.com [10.36.7.219]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u73GMoak009808; Wed, 3 Aug 2016 12:22:58 -0400 From: "Daniel P. Berrange" To: qemu-devel@nongnu.org Date: Wed, 3 Aug 2016 17:22:38 +0100 Message-Id: <1470241360-3574-4-git-send-email-berrange@redhat.com> In-Reply-To: <1470241360-3574-1-git-send-email-berrange@redhat.com> References: <1470241360-3574-1-git-send-email-berrange@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Wed, 03 Aug 2016 16:23:00 +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 3/5] sclpconsole: 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: Cornelia Huck , qemu-arm@nongnu.org, qemu-ppc@nongnu.org, Gerd Hoffmann , Amit Shah , Paolo Bonzini Errors-To: qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org Sender: "Qemu-devel" X-TUID: skara4SYiRsl 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(). 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) -- 2.7.4