linux-kernel - [PATCH] printk: allow setting DEFAULT_MESSAGE

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Message-ID: <20110125235700.GR8008@google.com>
Date:	Tue, 25 Jan 2011 15:57:00 -0800
From:	Mandeep Singh Baines <msb@...omium.org>
To:	linux-kernel@...r.kernel.org
Cc:	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	olofj@...omium.org
Subject: [PATCH] printk: allow setting DEFAULT_MESSAGE_LEVEL via Kconfig

We've been burned by regressions/bugs which we later realized could
have been triaged quicker if only we'd paid closer attention to
dmesg. To make it easier to audit dmesg, we'd like to make
DEFAULT_MESSAGE_LEVEL Kconfig-settable. That way we can set it to
KERN_NOTICE and audit any messages <= KERN_WARNING.

Signed-off-by: Mandeep Singh Baines <msb@...omium.org>
---
 kernel/printk.c   |    2 +-
 lib/Kconfig.debug |   12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/kernel/printk.c b/kernel/printk.c
index 5ddd291..f91a7fd 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -59,7 +59,7 @@ void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...)
 #define __LOG_BUF_LEN	(1 << CONFIG_LOG_BUF_SHIFT)
 
 /* printk's without a loglevel use this.. */
-#define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */
+#define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL
 
 /* We show everything that is MORE important than this.. */
 #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 28b42b9..67b42fa 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -9,6 +9,18 @@ config PRINTK_TIME
 	  operations.  This is useful for identifying long delays
 	  in kernel startup.
 
+config DEFAULT_MESSAGE_LOGLEVEL
+	int "Default message log level (1-7)"
+	range 1 7
+	depends on PRINTK
+	default "4"
+	help
+	  Default log level for printk statements with no specified priority.
+
+	  This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
+	  that are auditing their logs closely may want to set it to a lower
+	  priority.
+
 config ENABLE_WARN_DEPRECATED
 	bool "Enable __deprecated logic"
 	default y
-- 
1.7.3.1

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