linux-kernel - [RFC][PATCH 3/4] ntp: Use printk

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Date:	Fri, 29 May 2015 13:24:27 -0700
From:	John Stultz <john.stultz@...aro.org>
To:	lkml <linux-kernel@...r.kernel.org>
Cc:	John Stultz <john.stultz@...aro.org>,
	Prarit Bhargava <prarit@...hat.com>,
	Daniel Bristot de Oliveira <bristot@...hat.com>,
	Richard Cochran <richardcochran@...il.com>,
	Jan Kara <jack@...e.cz>, Jiri Bohac <jbohac@...e.cz>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Shuah Khan <shuahkh@....samsung.com>
Subject: [RFC][PATCH 3/4] ntp: Use printk_deferred in leapsecond path

Looking over the leapsecond code, I noticed the printk messages
reporting the leapsecond insertion in the second_overflow path
were not using the printk_deferred method. This was surprising
since the printk_deferred method was added in part to avoid
printk-ing while holding the timekeeping locks.

See 6d9bcb621b0b (timekeeping: use printk_deferred when holding
timekeeping seqlock) for further rational.

I can only guess that this omission was a git add -p oversight.

Folks particularly worried about leapsecond crashes should
probably pay attention to this patch. Pending review, Its likely
a -stable candidate.

Cc: Prarit Bhargava <prarit@...hat.com>
Cc: Daniel Bristot de Oliveira <bristot@...hat.com>
Cc: Richard Cochran <richardcochran@...il.com>
Cc: Jan Kara <jack@...e.cz>
Cc: Jiri Bohac <jbohac@...e.cz>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Shuah Khan <shuahkh@....samsung.com>
Signed-off-by: John Stultz <john.stultz@...aro.org>
---
 kernel/time/ntp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 7a68100..472591e 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -393,7 +393,7 @@ int second_overflow(unsigned long secs)
 		else if (secs % 86400 == 0) {
 			leap = -1;
 			time_state = TIME_OOP;
-			printk(KERN_NOTICE
+			printk_deferred(KERN_NOTICE
 				"Clock: inserting leap second 23:59:60 UTC\n");
 		}
 		break;
@@ -403,7 +403,7 @@ int second_overflow(unsigned long secs)
 		else if ((secs + 1) % 86400 == 0) {
 			leap = 1;
 			time_state = TIME_WAIT;
-			printk(KERN_NOTICE
+			printk_deferred(KERN_NOTICE
 				"Clock: deleting leap second 23:59:59 UTC\n");
 		}
 		break;
-- 
1.9.1

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