From patchwork Sun Jul 18 07:47:57 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Volker_R=C3=BCmelin?= X-Patchwork-Id: 12384163 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=-13.8 required=3.0 tests=BAYES_00, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 476C2C636CA for ; Sun, 18 Jul 2021 07:49:16 +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 D483C61166 for ; Sun, 18 Jul 2021 07:49:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D483C61166 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=t-online.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:51872 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m51Y2-0006ri-Qs for qemu-devel@archiver.kernel.org; Sun, 18 Jul 2021 03:49:14 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40260) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m51X4-0005HO-K1 for qemu-devel@nongnu.org; Sun, 18 Jul 2021 03:48:14 -0400 Received: from mailout08.t-online.de ([194.25.134.20]:54284) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m51X2-0002vG-Ji for qemu-devel@nongnu.org; Sun, 18 Jul 2021 03:48:14 -0400 Received: from fwd33.aul.t-online.de (fwd33.aul.t-online.de [172.20.27.144]) by mailout08.t-online.de (Postfix) with SMTP id 555164380; Sun, 18 Jul 2021 09:48:05 +0200 (CEST) Received: from linpower.localnet (ExTgZZZQwhTdfvh3hEOGAMLKCM-rdo+oFRahncigUbNR48DYAzAnUxRrTdJiFqtgpy@[79.208.26.7]) by fwd33.t-online.de with (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384 encrypted) esmtp id 1m51Wr-48wYLo0; Sun, 18 Jul 2021 09:48:01 +0200 Received: by linpower.localnet (Postfix, from userid 1000) id F16922000A1; Sun, 18 Jul 2021 09:47:57 +0200 (CEST) From: =?utf-8?q?Volker_R=C3=BCmelin?= To: Gerd Hoffmann Subject: [PATCH for 6.2 2/2] ui/gtk: drop chars if the chardev frontend makes no progress Date: Sun, 18 Jul 2021 09:47:57 +0200 Message-Id: <20210718074757.22489-2-vr_qemu@t-online.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <9e436e5c-ed11-69ec-3cb9-a19cbf96cb08@t-online.de> References: <9e436e5c-ed11-69ec-3cb9-a19cbf96cb08@t-online.de> MIME-Version: 1.0 X-ID: ExTgZZZQwhTdfvh3hEOGAMLKCM-rdo+oFRahncigUbNR48DYAzAnUxRrTdJiFqtgpy X-TOI-EXPURGATEID: 150726::1626594481-00013209-AD406C60/0/0 CLEAN NORMAL X-TOI-MSGID: 0b44b172-fef3-418d-8d20-c28e4b823a00 Received-SPF: none client-ip=194.25.134.20; envelope-from=volker.ruemelin@t-online.de; helo=mailout08.t-online.de X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: Zack Marvel , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Currently there is no limit how long the virtual console chardev backend retries to send remaining characters in the buffer. Drop the characters after a timeout if the chardev frontend doesn't accept characters. The timeout was calculated from arbitrarily selected constants. It was assumed that 50 baud is the slowest bit rate and that a character has at maximum one start bit, eight data bits, one parity bit and two stop bits. For a good safety margin, this time was multiplied by eight. This results in a timeout of 1 / (50 bits / s) * 12 bits * 8 = 1.92 s. Signed-off-by: Volker Rümelin --- include/ui/gtk.h | 2 ++ ui/gtk.c | 47 +++++++++++++++++++++++++++++++++++++++-------- 2 files changed, 41 insertions(+), 8 deletions(-) diff --git a/include/ui/gtk.h b/include/ui/gtk.h index 4714218376..2771b1aa91 100644 --- a/include/ui/gtk.h +++ b/include/ui/gtk.h @@ -67,6 +67,8 @@ typedef struct VirtualVteConsole { Chardev *chr; QEMUTimer *kbd_timer; Fifo8 out_fifo; + int64_t be_last_write; + bool be_can_write; bool echo; } VirtualVteConsole; #endif diff --git a/ui/gtk.c b/ui/gtk.c index b95b077b65..c22f4a0329 100644 --- a/ui/gtk.c +++ b/ui/gtk.c @@ -1711,8 +1711,20 @@ static const TypeInfo char_gd_vc_type_info = { .class_init = char_gd_vc_class_init, }; +static uint32_t gd_vc_send_backoff(uint32_t elapsed) +{ + if (elapsed <= 500) { + return 1000; + } else if (elapsed >= 50000) { + return 100000; + } + + return elapsed * 2; +} + static void gd_vc_send_chars(VirtualConsole *vc) { + int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); uint32_t len, avail; const uint8_t *buf; @@ -1721,21 +1733,39 @@ static void gd_vc_send_chars(VirtualConsole *vc) if (len > avail) { len = avail; } - while (len > 0) { + if (len > 0) { uint32_t size; - buf = fifo8_pop_buf(&vc->vte.out_fifo, len, &size); - qemu_chr_be_write(vc->vte.chr, (uint8_t *)buf, size); - len -= size; - avail -= size; + do { + buf = fifo8_pop_buf(&vc->vte.out_fifo, len, &size); + qemu_chr_be_write(vc->vte.chr, (uint8_t *)buf, size); + len -= size; + avail -= size; + } while (len > 0); + + vc->vte.be_can_write = true; + vc->vte.be_last_write = now; } /* * characters are pending: we send them a bit later (XXX: * horrible, should change char device API) */ if (avail > 0) { - timer_mod(vc->vte.kbd_timer, - qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + 1); + if (vc->vte.be_can_write) { + uint64_t elapsed = (now - vc->vte.be_last_write) / SCALE_US; + + if (elapsed < 1920000) { + timer_mod(vc->vte.kbd_timer, + now / SCALE_US + gd_vc_send_backoff(elapsed)); + } else { + /* no progress since 1.92s */ + vc->vte.be_can_write = false; + fifo8_reset(&vc->vte.out_fifo); + } + } else { + /* the chardev frontend hasn't accepted chars in a long time */ + fifo8_reset(&vc->vte.out_fifo); + } } } @@ -1794,7 +1824,8 @@ static GSList *gd_vc_vte_init(GtkDisplayState *s, VirtualConsole *vc, vc->vte.echo = vcd->echo; vc->vte.chr = chr; fifo8_create(&vc->vte.out_fifo, 16); - vc->vte.kbd_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL, + vc->vte.be_can_write = false; + vc->vte.kbd_timer = timer_new_us(QEMU_CLOCK_VIRTUAL, gd_vc_timer_send_chars, vc); vcd->console = vc;