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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 19895C432C0 for ; Fri, 22 Nov 2019 10:58:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E25DB2071C for ; Fri, 22 Nov 2019 10:58:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574420293; bh=Er1C0v6WOPG9MdMVv1ytWpIZtgZTMmVtrfz1ICT1oRc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=2nKwEZzOVtjep0JrEjVKVYfWG25Gx1GQWUlrVPV8+ohk4oLsh2lCaC+GcqgNXPEid ykGlW9GcvnqT3JJD5XWH1E9x+VUKg5Qd11WVyowuN8uVGkeP+738w9MfTf0/c7lTbI 7LAw2kvqEbj/OboEve2uFAnkUbJ9tecdj4BW9wcQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730117AbfKVK6L (ORCPT ); Fri, 22 Nov 2019 05:58:11 -0500 Received: from mail.kernel.org ([198.145.29.99]:47636 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730079AbfKVK6G (ORCPT ); Fri, 22 Nov 2019 05:58:06 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6AC972075B; Fri, 22 Nov 2019 10:58:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574420285; bh=Er1C0v6WOPG9MdMVv1ytWpIZtgZTMmVtrfz1ICT1oRc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NhBvFC3EqXdQVHKUdbuNZz4S6vYQupVumcwBIFMPV8lY22jp4e4N/bOrLSyy/t1me fUiRMaXw8S9ElPcfF/V9xN7dc3W/2eUfv1+Nz5ZvNTEobNktRj3GyyiXydjLe2TW0O Rarsb8Clo0tsQF2OxRQeC2Of0D1Omaf9j4mqSG/c= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, Steven Rostedt Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sergey Senozhatsky , Peter Zijlstra , Sergey Senozhatsky , Petr Mladek , Sasha Levin Subject: [PATCH 4.19 055/220] printk: Do not miss new messages when replaying the log Date: Fri, 22 Nov 2019 11:27:00 +0100 Message-Id: <20191122100916.121259277@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191122100912.732983531@linuxfoundation.org> References: <20191122100912.732983531@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Petr Mladek [ Upstream commit f92b070f2dc89a8ff1a0cc8b608e20abef894c7d ] The variable "exclusive_console" is used to reply all existing messages on a newly registered console. It is cleared when all messages are out. The problem is that new messages might appear in the meantime. These are then visible only on the exclusive console. The obvious solution is to clear "exclusive_console" after we replay all messages that were already proceed before we started the reply. Reported-by: Sergey Senozhatsky Link: http://lkml.kernel.org/r/20180913123406.14378-1-pmladek@suse.com To: Steven Rostedt Cc: Peter Zijlstra Cc: Sergey Senozhatsky Cc: linux-kernel@vger.kernel.org Acked-by: Sergey Senozhatsky Signed-off-by: Petr Mladek Signed-off-by: Sasha Levin --- kernel/printk/printk.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index d0d03223b45b1..b627954061bb6 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -423,6 +423,7 @@ static u32 log_next_idx; /* the next printk record to write to the console */ static u64 console_seq; static u32 console_idx; +static u64 exclusive_console_stop_seq; /* the next printk record to read after the last 'clear' command */ static u64 clear_seq; @@ -2014,6 +2015,7 @@ static u64 syslog_seq; static u32 syslog_idx; static u64 console_seq; static u32 console_idx; +static u64 exclusive_console_stop_seq; static u64 log_first_seq; static u32 log_first_idx; static u64 log_next_seq; @@ -2381,6 +2383,12 @@ void console_unlock(void) goto skip; } + /* Output to all consoles once old messages replayed. */ + if (unlikely(exclusive_console && + console_seq >= exclusive_console_stop_seq)) { + exclusive_console = NULL; + } + len += msg_print_text(msg, console_msg_format & MSG_FORMAT_SYSLOG, text + len, @@ -2423,10 +2431,6 @@ void console_unlock(void) console_locked = 0; - /* Release the exclusive_console once it is used */ - if (unlikely(exclusive_console)) - exclusive_console = NULL; - raw_spin_unlock(&logbuf_lock); up_console_sem(); @@ -2711,6 +2715,7 @@ void register_console(struct console *newcon) * the already-registered consoles. */ exclusive_console = newcon; + exclusive_console_stop_seq = console_seq; } console_unlock(); console_sysfs_notify(); -- 2.20.1