linux-kernel - [PATCH v2] printk: allow setting DEFAULT_MESSAGE

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Message-ID: <20110209005231.GE632@google.com>
Date:	Tue, 8 Feb 2011 16:52:31 -0800
From:	Mandeep Singh Baines <msb@...omium.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Joe Perches <joe@...ches.com>, msb@...omium.org, mingo@...e.hu,
	olofj@...omium.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] printk: allow setting DEFAULT_MESSAGE_LEVEL via Kconfig

Andrew Morton (akpm@...ux-foundation.org) wrote:
> On Tue, 08 Feb 2011 13:52:51 -0800
> Joe Perches <joe@...ches.com> wrote:
> 
> > On Tue, 2011-02-08 at 13:49 -0800, akpm@...ux-foundation.org wrote:
> > > The patch titled
> > >      printk: allow setting DEFAULT_MESSAGE_LEVEL via Kconfig
> > > has been removed from the -mm tree.
> > > This patch was dropped because it had testing failures
> > 
> > The patch seems pretty simple.
> > What kind of testing failures did it have?
> > 
> 
> CONFIG_DEFAULT_MESSAGE_LOGLEVEL undefined with CONFIG_PRINTK=n (Randy)

D'oh. Fixed.

---

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 |   11 +++++++++++
 2 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/kernel/printk.c b/kernel/printk.c
index 2ddbdc7..bddeee8 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -53,7 +53,7 @@ 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 3967c23..bd1760c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -9,6 +9,17 @@ 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
+	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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