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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 0ACE2C5ACB3 for ; Thu, 16 Nov 2023 11:55:03 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1r3aws-0006i1-Vn; Thu, 16 Nov 2023 06:54:19 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1r3awq-0006hj-Lb; Thu, 16 Nov 2023 06:54:17 -0500 Received: from mail-pf1-x429.google.com ([2607:f8b0:4864:20::429]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1r3awp-0007hC-80; Thu, 16 Nov 2023 06:54:16 -0500 Received: by mail-pf1-x429.google.com with SMTP id d2e1a72fcca58-6c431ca7826so635708b3a.0; Thu, 16 Nov 2023 03:54:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1700135652; x=1700740452; darn=nongnu.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=khu5P4E16LAd1R2e6yUGq0YwfAOQmxoguNRACDoGfCg=; b=Ggihks2ADxgnmYv6LYoRpvf4YZC3xtuHDtqckIgwJJRaX2uyoj5g41/nIKdCLa0kvC oWOr4WxfmA0771drr4nxt3q33NzJqEnOQXISA+d/b4Xnz657djXADDIfn1iHROkJgAtQ UBnsqWaaZRF2dbUDFl4vGs52sDLjUHQ3Ae5jbUOgrONjrIsAn4KXxZLBdgPYiskPuHTu aZMb4hWfu2VLd+sMx1seISDkfy3X6z6c+rcXsiBiDPhisDA1iM96gNgXCyLHvnXRl8yX dWTK2ludjYU2JTj1xn7j0B5FTni+p//1ZfGBAO37K39/W6pBrJ0VZcOa5zAHyuGMOWAg VhUQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700135652; x=1700740452; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=khu5P4E16LAd1R2e6yUGq0YwfAOQmxoguNRACDoGfCg=; b=rRvodotZke8T1nvB0gNJF6BBae1DxoVBSCNON/69hQtc4Jqsn4GrC+OibPyWelP81n MBX5uuQn/vd1M32F70ecu1wfPZppeQg6VFOzGuSm4zez2P7EXA3blkFZkiQh7riDusuV E0D9CMYRU4OwmjnKD4FcOKGNS2N/NkOYITyxaUkdeu7bm6fExRlDHc8+dnPESL2cGl04 KGMCT4XQvM6JrKzYruRMZ09fHPeRKw1rtd38ZDfYgf843EEQFSrAj95wG1T59b3pOdwI 1YStyG1ICbJuTpBUJa8ZvOQ7mfKBXnv1s5CjT2UghYpmFR4qB8p/qsHnpCZMjQelNZmw 0N3w== X-Gm-Message-State: AOJu0YxesbEplqopFuBIGwLLxe+3QU+K5om+8oMUJza+6ra0urMBGKR8 9XbGa/iyUHxW6NDNBwl47dbEP7KUW/c= X-Google-Smtp-Source: AGHT+IFymt2qv910Oa/LderXVtoyd1pY2xzwWMs/AkszvU1nAyn732QPn/4KMAQr6wYZ+Pu7Ddu6/g== X-Received: by 2002:a05:6a00:1e18:b0:68f:f650:3035 with SMTP id gx24-20020a056a001e1800b0068ff6503035mr13497466pfb.12.1700135652048; Thu, 16 Nov 2023 03:54:12 -0800 (PST) Received: from wheely.local0.net ([210.84.53.86]) by smtp.gmail.com with ESMTPSA id n19-20020a62e513000000b006c60b150383sm4507960pff.12.2023.11.16.03.54.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Nov 2023 03:54:11 -0800 (PST) From: Nicholas Piggin To: qemu-devel@nongnu.org Cc: Nicholas Piggin , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , Paolo Bonzini , Pavel Dovgalyuk , Cleber Rosa , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Wainer dos Santos Moschetta , Beraldo Leal , Ani Sinha , =?UTF-8?q?Daniel=20P=20=2E=20Berrang=C3=A9?= , "Thomas Huth" , "John Snow" , qemu-ppc@nongnu.org, =?UTF-8?q?Alex=20Benn=C3=A9e?= Subject: [PATCH 2/3] chardev: report blocked write to chardev backend Date: Thu, 16 Nov 2023 21:53:53 +1000 Message-ID: <20231116115354.228678-2-npiggin@gmail.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231116115354.228678-1-npiggin@gmail.com> References: <20231116115354.228678-1-npiggin@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::429; envelope-from=npiggin@gmail.com; helo=mail-pf1-x429.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org If a chardev socket is not read, it will eventually fill and QEMU can block attempting to write to it. A difficult bug in avocado tests where the console socket was not being read from caused this hang. warn if a chardev write is blocked for 100ms. Signed-off-by: Nicholas Piggin --- This is not necessary for the fix but it does trigger in the failing avocado test without the previous patch applied. Maybe it would be helpful? Thanks, Nick chardev/char.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/chardev/char.c b/chardev/char.c index 996a024c7a..7c375e3cc4 100644 --- a/chardev/char.c +++ b/chardev/char.c @@ -114,6 +114,8 @@ static int qemu_chr_write_buffer(Chardev *s, { ChardevClass *cc = CHARDEV_GET_CLASS(s); int res = 0; + int nr_retries = 0; + *offset = 0; qemu_mutex_lock(&s->chr_write_lock); @@ -126,6 +128,10 @@ static int qemu_chr_write_buffer(Chardev *s, } else { g_usleep(100); } + if (++nr_retries == 1000) { /* 100ms */ + warn_report("Chardev '%s' write blocked for > 100ms, " + "socket buffer full?", s->label); + } goto retry; } -- 2.42.0