linux-kernel - [PATCH 1/6] printk: Remove outdated comment

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Date:	Thu, 13 Mar 2014 16:58:33 +0100
From:	Jan Kara <jack@...e.cz>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	LKML <linux-kernel@...r.kernel.org>, pmladek@...e.cz,
	Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Jan Kara <jack@...e.cz>
Subject: [PATCH 1/6] printk: Remove outdated comment

Comment about interesting interlocking between lockbuf_lock and
console_sem is outdated. It was added in 2002 by commit
a880f45a48be2956d2c78a839c472287d54435c1 during conversion of
console_lock to console_sem + lockbuf_lock. At that time
release_console_sem() (today's equivalent is console_unlock()) was
indeed using lockbuf_lock to avoid races between trylock on console_sem
in printk() and unlock of console_sem. However these days the
interlocking is gone and the races are avoided by rechecking logbuf
state after releasing console_sem.

Signed-off-by: Jan Kara <jack@...e.cz>
---
 kernel/printk/printk.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 4dae9cbe9259..bd7ee2a9f960 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -206,8 +206,7 @@ struct printk_log {
 };

 /*
- * The logbuf_lock protects kmsg buffer, indices, counters. It is also
- * used in interesting ways to provide interlocking in console_unlock();
+ * The logbuf_lock protects kmsg buffer, indices, counters.
  */
 static DEFINE_RAW_SPINLOCK(logbuf_lock);

-- 
1.8.1.4

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