linux-kernel - [PATCH v4 3/3] printk: check CON_ENABLED in have_callable

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Date:	Sat, 13 Feb 2016 03:37:12 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Petr Mladek <pmladek@...e.com>, Jan Kara <jack@...e.com>,
	Tejun Heo <tj@...nel.org>, Kyle McMartin <kyle@...nel.org>,
	Dave Jones <davej@...emonkey.org.uk>,
	Calvin Owens <calvinowens@...com>,
	linux-kernel@...r.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: [PATCH v4 3/3] printk: check CON_ENABLED in have_callable_console()

have_callable_console() must also test CON_ENABLED bit, not just
CON_ANYTIME. We may have disabled CON_ANYTIME console so printk
can wrongly assume that it's safe to call_console_drivers().

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
---
 kernel/printk/printk.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 9f0c3e1..9917f69 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2139,7 +2139,8 @@ static int have_callable_console(void)
 	struct console *con;
 
 	for_each_console(con)
-		if (con->flags & CON_ANYTIME)
+		if ((con->flags & CON_ENABLED) &&
+				(con->flags & CON_ANYTIME))
 			return 1;
 
 	return 0;
-- 
2.7.1