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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 DDEB1C04EBD for ; Tue, 16 Oct 2018 05:04:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 979FD2054F for ; Tue, 16 Oct 2018 05:04:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="LXSRp8Vh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 979FD2054F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727601AbeJPMxR (ORCPT ); Tue, 16 Oct 2018 08:53:17 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:35872 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727008AbeJPMxR (ORCPT ); Tue, 16 Oct 2018 08:53:17 -0400 Received: by mail-pg1-f195.google.com with SMTP id f18-v6so10252198pgv.3; Mon, 15 Oct 2018 22:04:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=zzFIh7fM68tNcvX7bLWay90B5Fk+fBTJ+wuZ+4raSCM=; b=LXSRp8VhXj3g2Fk3ooTCqSYzgxNH+tJfH1bAvQ5KuqT4d39aieVKU6JqgKp76E8Guf c5gNQBsRdnrifwViu+Yc7ucXO5TXX5K+2tVWJ4CvPtVnhO4sVyZuLnAKlkyV3P8ji/fR 6khbaNuakA1GO2qz9LskhllVWLsr2fzUj16ng92/VIgdvE6JC+Q0wfEK+QQ9MJmoEUoh lF3o+ZALhLzqnnz3wKy7PQJy6yYn0pSfgVxG6v9/kr57Qz7OXHvvZF0Ex4KWvHPe0b3q 1y7HvFmAtzSevfUapUE/17cpis8USdZwb10RiGTkQV18I13FgcjG+vGCnTfUMIxIdcEV zwOw== 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:mime-version :content-transfer-encoding; bh=zzFIh7fM68tNcvX7bLWay90B5Fk+fBTJ+wuZ+4raSCM=; b=Y8nL1e08ju80wVS7O67AxBxMFiXxtqYWTL2Q3udLoFjLBLzxqIGybztUOrk+CX/rxM FUZI651PBMYq/jbNbow+GfR/JgrPTTL3jswyQsPQ2DM6nWbuaWTWQ4cNTfPaC8Q2DcF1 kO+y39YCPXmfH4ut9bakug9XKUyYsUPC3A8WxZ+lGi3uch8mOTjlme3RI2aSsKQlLD+a t7zbgd2405kk4JXSvKOmsmpKVmc20anWkc/sh1tt47O/FsWo2QalCzZ2Bj6MolNi8ml7 EKtRJ4BLCpWxeoeYL0qLs/9OCNtyFOLurKipHLsg7KRUjqj6gD6RwNC6zDN/zCIAOXBF M0cg== X-Gm-Message-State: ABuFfohFzUiAzBnrfaWbOrEUDNgB/IVt658CdcUPA4+huDp6KPnsiHwp 0yi2CxPjnbOgF4YCJjK8Ww3LiSwK X-Google-Smtp-Source: ACcGV63/G5OFSgqqcvhUYd4ptPCkqZUZ4Ntmi47XNZSKTpMTmxZ/SHxvUWVChk4eBHK0vgw29sVTcg== X-Received: by 2002:a63:b4b:: with SMTP id a11-v6mr17827575pgl.97.1539666280957; Mon, 15 Oct 2018 22:04:40 -0700 (PDT) Received: from localhost.localdomain ([175.223.10.117]) by smtp.gmail.com with ESMTPSA id e131-v6sm19353225pfc.52.2018.10.15.22.04.34 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 15 Oct 2018 22:04:39 -0700 (PDT) From: Sergey Senozhatsky X-Google-Original-From: Sergey Senozhatsky To: linux-kernel@vger.kernel.org Cc: Petr Mladek , Steven Rostedt , Daniel Wang , Peter Zijlstra , Andrew Morton , Linus Torvalds , Greg Kroah-Hartman , Alan Cox , Jiri Slaby , Peter Feiner , linux-serial@vger.kernel.org, Sergey Senozhatsky , Sergey Senozhatsky Subject: [RFC][PATCHv2 0/4] less deadlock prone serial consoles Date: Tue, 16 Oct 2018 14:04:24 +0900 Message-Id: <20181016050428.17966-1-sergey.senozhatsky@gmail.com> X-Mailer: git-send-email 2.19.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, RFC The patch set reduces the number of ways serial consoles can deadlock the system, including the recently reported deadlock in panic(). The test scenario I ran on my x86_64 box: - panic() the system while one of the CPUs holds 8250's uart_port->lock. Test results: base | patched ----------------------------------------- deadlock | flush logbuf | reboot the system To keep the cover letter short, please find full description in commit messages. P.S. since this is RFC I modify only 8250 serial driver. Sergey Senozhatsky (4): panic: avoid deadlocks in re-entrant console drivers printk: move printk_safe macros to printk header seial: introduce uart_port locking helpers tty: 8250: switch to uart_port locking helpers drivers/tty/serial/8250/8250_core.c | 8 +-- drivers/tty/serial/8250/8250_dma.c | 4 +- drivers/tty/serial/8250/8250_port.c | 81 +++++++++++++---------------- include/linux/printk.h | 40 ++++++++++++++ include/linux/serial_core.h | 48 +++++++++++++++++ kernel/panic.c | 6 +++ kernel/printk/internal.h | 37 ------------- kernel/printk/printk_safe.c | 6 ++- 8 files changed, 141 insertions(+), 89 deletions(-) -- 2.19.1