From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759422Ab2HYDv0 (ORCPT ); Fri, 24 Aug 2012 23:51:26 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:19860 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754727Ab2HYDux (ORCPT ); Fri, 24 Aug 2012 23:50:53 -0400 X-Authority-Analysis: v=2.0 cv=LIjkseq9 c=1 sm=0 a=rXTBtCOcEpjy1lPqhTCpEQ==:17 a=mNMOxpOpBa8A:10 a=Ciwy3NGCPMMA:10 a=2k-WFFBCSGIA:10 a=5SG0PmZfjMsA:10 a=bbbx4UPp9XUA:10 a=seBqgFWFO7gA:10 a=meVymXHHAAAA:8 a=z6gsHLkEAAAA:8 a=Thplo4k3AAAA:8 a=VwQbUJbxAAAA:8 a=ohp7AQS0vaYIBeFxnjgA:9 a=SXYrDhgbg5QA:10 a=Zh68SRI7RUMA:10 a=rXTBtCOcEpjy1lPqhTCpEQ==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.115.198 Message-Id: <20120825035051.968542677@goodmis.org> User-Agent: quilt/0.60-1 Date: Fri, 24 Aug 2012 23:49:01 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-rt-users Cc: Thomas Gleixner , Carsten Emde , John Kacur , Frank Rowand , Frank Subject: [PATCH RT 1/2] fix printk flush of messages References: <20120825034900.144648579@goodmis.org> Content-Disposition: inline; filename=0001-fix-printk-flush-of-messages.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Updates console-make-rt-friendly.patch #ifdef CONFIG_PREEMPT_RT_FULL, printk() output is never flushed by printk() because: # 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 On system boot some printk() output is flushed because register_console() and tty_open() call console_unlock(). This change also fixes the problem that was previously fixed by preempt-rt-allow-immediate-magic-sysrq-output-for-preempt_rt_full.patch Signed-off-by: Frank Rowand Cc: Frank Link: http://lkml.kernel.org/r/4FB44FD0.4090800@am.sony.com Signed-off-by: Thomas Gleixner --- kernel/printk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/printk.c b/kernel/printk.c index 60f4290..f2c459f 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -835,7 +835,7 @@ static int console_trylock_for_printk(unsigned int cpu, unsigned long flags) { #ifdef CONFIG_PREEMPT_RT_FULL int lock = (!early_boot_irqs_disabled && !irqs_disabled_flags(flags) && - !preempt_count()) || sysrq_in_progress; + (preempt_count() <= 1)) || sysrq_in_progress; #else int lock = 1; #endif -- 1.7.10.4