Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752146AbaABWzv (ORCPT ); Thu, 2 Jan 2014 17:55:51 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:43108 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751849AbaABWzt (ORCPT ); Thu, 2 Jan 2014 17:55:49 -0500 Date: Thu, 2 Jan 2014 14:55:48 -0800 From: Andrew Morton To: Arun KS Cc: linux-kernel@vger.kernel.org, joe@perches.com, tj@kernel.org, fweisbec@gmail.com, paul.gortmaker@windriver.com Subject: Re: [PATCH] printk: flush conflicting continuation line Message-Id: <20140102145548.f3fe2c3fd3ea706ed388685c@linux-foundation.org> In-Reply-To: References: X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3423 Lines: 96 On Wed, 1 Jan 2014 17:44:06 +0530 Arun KS wrote: > >From d751f9a0cb6329ae3171f6e1cb85e4a3aa792d73 Mon Sep 17 00:00:00 2001 > From: Arun KS > Date: Wed, 1 Jan 2014 17:24:46 +0530 > Subject: printk: flush conflicting continuation line > > An earlier newline was missing and current print is from different task. > In this scenario flush the continuation line and store this line seperatly. > > This patch fix the below scenario of timestamp interleaving, > <6>[ 28.154370 ] read_word_reg : reg[0x 3], reg[0x 4] data [0x 642] > <6>[ 28.155428 ] uart disconnect > <6>[ 31.947341 ] dvfs[cpufreq.c<275>]:plug-in cpu<1> done > <4>[ 28.155445 ] UART detached : send switch state 201 > <6>[ 32.014112 ] read_reg : reg[0x 3] data[0x21] > > ... > > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -1604,7 +1604,10 @@ asmlinkage int vprintk_emit(int facility, int level, > if (!(lflags & LOG_PREFIX)) > stored = cont_add(facility, level, text, text_len); > cont_flush(LOG_NEWLINE); > - } > + /* Flush conflicting buffer. An earlier newline was missing > + * and current print is from different task */ > + } else if (cont.len && cont.owner != current) > + cont_flush(LOG_NEWLINE); > > if (!stored) > log_store(facility, level, lflags, 0, Your email client makes a horrid mess of the patches :( I *think* it's right. But the code can be significantly simplified and optimised. Please review: } else { bool stored = false; /* * If an earlier newline was missing and it was the same task, * either merge it with the current buffer and flush, or if * there was a race with interrupts (prefix == true) then just * flush it out and store this line separately. * If the preceding printk was from a different task and missed * a newline, flush and append the newline. */ if (cont.len) { if (cont.owner == current && !(lflags & LOG_PREFIX)) stored = cont_add(facility, level, text, text_len); cont_flush(LOG_NEWLINE); } if (!stored) log_store(facility, level, lflags, 0, dict, dictlen, text, text_len); } --- a/kernel/printk/printk.c~printk-flush-conflicting-continuation-line-fix +++ a/kernel/printk/printk.c @@ -1595,15 +1595,15 @@ asmlinkage int vprintk_emit(int facility * either merge it with the current buffer and flush, or if * there was a race with interrupts (prefix == true) then just * flush it out and store this line separately. + * If the preceding printk was from a different task and missed + * a newline, flush and append the newline. */ - if (cont.len && cont.owner == current) { - if (!(lflags & LOG_PREFIX)) - stored = cont_add(facility, level, text, text_len); - cont_flush(LOG_NEWLINE); - /* Flush conflicting buffer. An earlier newline was missing - * and current print is from different task */ - } else if (cont.len && cont.owner != current) + if (cont.len) { + if (cont.owner == current && !(lflags & LOG_PREFIX)) + stored = cont_add(facility, level, text, + text_len); cont_flush(LOG_NEWLINE); + } if (!stored) log_store(facility, level, lflags, 0, _ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/