Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758727Ab2EUU7x (ORCPT ); Mon, 21 May 2012 16:59:53 -0400 Received: from tx2ehsobe005.messaging.microsoft.com ([65.55.88.15]:58185 "EHLO tx2outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758513Ab2EUU7v (ORCPT ); Mon, 21 May 2012 16:59:51 -0400 X-SpamScore: -12 X-BigFish: VPS-12(zzbb2dI9371I1432N98dK4015Izz1202hzzz2fh2a8h668h839hd25hf0ah) X-Forefront-Antispam-Report: CIP:160.33.194.230;KIP:(null);UIP:(null);IPV:NLI;H:usculsndmail03v.am.sony.com;RD:mail03.sonyusa.com;EFVD:NLI Message-ID: <4FBAACAC.3080300@am.sony.com> Date: Mon, 21 May 2012 13:59:24 -0700 From: Frank Rowand Reply-To: User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110428 Fedora/3.1.10-1.fc14 Thunderbird/3.1.10 MIME-Version: 1.0 To: Venkat Subbiah CC: "Rowand, Frank" , "tglx@linutronix.de" , "linux-kernel@vger.kernel.org" , "linux-rt-users@vger.kernel.org" Subject: Re: [PATCH RT 2/2] fix printk flush of messages References: <4FB44EF1.9050809@am.sony.com> <4FB44FD0.4090800@am.sony.com> <4FBAA150.6050308@caviumnetworks.com> In-Reply-To: <4FBAA150.6050308@caviumnetworks.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-OriginatorOrg: am.sony.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1721 Lines: 50 On 05/21/12 13:10, Venkat Subbiah wrote: > On 05/16/2012 06:09 PM, Frank Rowand wrote: >> Updates console-make-rt-friendly.patch >> >> #ifdef CONFIG_PREEMPT_RT_FULL, printk() output is never flushed by >> printk() because: > So this is an issue for printk() itself and is not just for early_printk()? > > > # some liberties taken in this pseudo-code to make it easier to follow > printk() > vprintk() > raw_spin_lock(&logbuf_lock) > # increment preempt_count(): > preempt_disable() > result = console_trylock_for_printk() > > As I read it console_trylock_for_printk() is called from printk() but in > code it is called from vprintk() Yes, I goofed on the indentation, starting at console_trylock_for_printk(). It should have been: # some liberties taken in this pseudo-code to make it easier to follow printk() vprintk() raw_spin_lock(&logbuf_lock) # increment preempt_count(): preempt_disable() result = console_trylock_for_printk() retval = 0 # lock will always be false, because preempt_count() will be >= 1 lock = ... && !preempt_count() if (lock) retval = 1 return retval # result will always be false since lock will always be false if (result) console_unlock() # this is where the printk() output would be flushed Thanks, Frank -- 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/