Commit ca1d432a authored Jun 04, 2014 by Jan Kara Committed by Linus Torvalds Jun 04, 2014

printk: remove outdated comment



Comment about interesting interlocking between lockbuf_lock and
console_sem is outdated.

It was added in 2002 by commit a880f45a48be 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@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 034633cc

kernel/printk/printk.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -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);