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 X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT autolearn=no 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 8F9B0C433DF for ; Thu, 4 Jun 2020 10:01:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6D78B204EA for ; Thu, 4 Jun 2020 10:01:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="f0FQClfi" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728370AbgFDKBk (ORCPT ); Thu, 4 Jun 2020 06:01:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40150 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726115AbgFDKBk (ORCPT ); Thu, 4 Jun 2020 06:01:40 -0400 Received: from mail-pj1-x1043.google.com (mail-pj1-x1043.google.com [IPv6:2607:f8b0:4864:20::1043]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 197D4C03E96D for ; Thu, 4 Jun 2020 03:01:40 -0700 (PDT) Received: by mail-pj1-x1043.google.com with SMTP id a45so2079014pje.1 for ; Thu, 04 Jun 2020 03:01:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id; bh=Clstppy/1La57TBLOjLA/wXNlzifwjjs+dcuhmyrmaM=; b=f0FQClfiS3taqRiHZVNQQ/xEoxPu/xT7VUjVZA/dUMwVQlw5oQLsBZsrBsVAMuud5z omxOeJKgsRb4M/AiakjwNjFdLagSAb1wYJ3PCu7bAcxesHdFl8zamT89hjwwAiNKGIxI bC9/cofrq2DuCMPQTgH5g6pU2zuvUPfgsWx8BHdPZW8loHBAuPwPV3VSQrCuTwYy8JAu 4VprYlBOiCALNM74NEryhPUfk7bs2b0hjMSbTMxnn9xWNRgYG1pn0fUQaorfVp6gm93h kv428ayG3bxzjYwF3E5c+O4VQrm9gfwf59WpXgwq6XLuWfu6UO/w5jM8so1FeVs53wXY Mkng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=Clstppy/1La57TBLOjLA/wXNlzifwjjs+dcuhmyrmaM=; b=lPhCFUsMwiDrW66XkjBaNs6I9oXQFuJ5Jz9k08qlcMaHwrPZbdR2LzSSYYJjF4HJsR YwbUKsapjUSsJGHWfhNLYRllvYQ8Bqg1tof/2f4UpyYaTdOWLAqQNXe5GJSj7zq9PZ9y PrVs2/SztkXecZmfeRgd0PHgZJ4yakOdtzfCY7FHayqJNcBLMGzeI0UY1aM4t8PHPFb6 VsURkH93xORZoT188cWc/PTbZYS8D+z0LhJkdcXWvZ4/H0JdMn1m6sVcnZ9ABvZyuP2T pjrWHFf9cY7G9QspPOiwpBV2eNdLSAEmI99b5zzNYXW7tEeXMPe7KhyR2PNSP4abwRGa tJTg== X-Gm-Message-State: AOAM5306SKOpAigt+ElT45MxXbQ2bfL3WzPqyGwEfB0bLoWVxz2i4cLY 2jZOnnJpFuCOYU3Z5kqls9FjLA== X-Google-Smtp-Source: ABdhPJzVjymj2KK9Fb597/6EVryJH8miLwm1wthbBL4tfu3R8Prui6WkFEIdRP6KmrRYYgDI9FEmfw== X-Received: by 2002:a17:90a:5aa4:: with SMTP id n33mr5297644pji.226.1591264899492; Thu, 04 Jun 2020 03:01:39 -0700 (PDT) Received: from localhost.localdomain ([117.252.66.248]) by smtp.gmail.com with ESMTPSA id np5sm5786992pjb.43.2020.06.04.03.01.34 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 04 Jun 2020 03:01:38 -0700 (PDT) From: Sumit Garg To: daniel.thompson@linaro.org Cc: kgdb-bugreport@lists.sourceforge.net, jason.wessel@windriver.com, dianders@chromium.org, pmladek@suse.com, sergey.senozhatsky@gmail.com, gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, Sumit Garg Subject: [PATCH v6 0/4] kdb: Improve console handling Date: Thu, 4 Jun 2020 15:31:15 +0530 Message-Id: <1591264879-25920-1-git-send-email-sumit.garg@linaro.org> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch-set is aimed to improve console handling especially when kdb operates in NMI context. Brief description of enhancements: - Add status check for console prior to invoking corresponding handler. - Fixup to avoid possible deadlock in NMI context due to usage of locks in the console handlers. - Prefer usage of polling I/O driver mode (lockless APIs) over invocation of console handlers. Changes in v6: - Replace early_con -> kgdboc_earlycon_io_ops.cons. - Added Petr's review tag on patch #1, #2 and #3. - Drop Doug's review tag from patch #4 due to early_con changes which I think needs a re-review. Changes in v5: - Rebased on top of tags/kgdb-5.8-rc1. - Get rid of kdb_io_write(). - Fixed issue reported by kbuild test robot. - Remove is_console from kgdboc_earlycon_io_ops as well. - Misc. comments. - Added Doug's review tag. Changes in v4: - Use dbg_io_ops->write_char() directly instead of passing it as a function pointer. - Use "struct console" rather than "struct tty_driver" for comparison. - Make commit descriptions and comments more informative. - Add review tag for patch #2. Changes in v3: - Split patch to have separate patch for console status check. - New patch to re-factor kdb message emit code. - New patch to prefer polling I/O over console mode. - Add code comments to describe usage of oops_in_progress. Changes in v2: - Use oops_in_progress directly instead of bust_spinlocks(). Sumit Garg (4): kdb: Re-factor kdb_printf() message write code kdb: Check status of console prior to invoking handlers kdb: Make kdb_printf() console handling more robust kdb: Switch to use safer dbg_io_ops over console APIs drivers/tty/serial/kgdb_nmi.c | 2 +- drivers/tty/serial/kgdboc.c | 32 +++++++++---------- drivers/usb/early/ehci-dbgp.c | 3 +- include/linux/kgdb.h | 5 ++- kernel/debug/kdb/kdb_io.c | 72 ++++++++++++++++++++++++++----------------- 5 files changed, 64 insertions(+), 50 deletions(-) -- 2.7.4