[PATCH] panic: Call console_verbose in panic

[PATCH] panic: Call console_verbose in panic

[Anton Blanchard]

Most distros turn the console verbosity down and that means a backtrace after
a panic never makes it to the console. I assume we haven't seen this because
a panic is often preceeded by an oops which will have called console_verbose.
There are however a lot of places we call panic directly, and they are
broken.

Use console_verbose like we do in the oops path to ensure a directly called
panic will print a backtrace.

Signed-off-by: Anton Blanchard <anton@samba.org>
---

Index: linux-2.6/kernel/panic.c
===================================================================
--- linux-2.6.orig/kernel/panic.c	2010-05-09 09:13:06.000000000 +1000
+++ linux-2.6/kernel/panic.c	2010-05-09 09:14:13.000000000 +1000
@@ -87,6 +87,7 @@ NORET_TYPE void panic(const char * fmt, 
 	 */
 	preempt_disable();
 
+	console_verbose();
 	bust_spinlocks(1);
 	va_start(args, fmt);
 	vsnprintf(buf, sizeof(buf), fmt, args);

Re: [PATCH] panic: Call console_verbose in panic

[Greg KH]

On Tue, May 11, 2010 at 08:59:59AM +1000, Anton Blanchard wrote:
> 
> Most distros turn the console verbosity down and that means a backtrace after
> a panic never makes it to the console. I assume we haven't seen this because
> a panic is often preceeded by an oops which will have called console_verbose.
> There are however a lot of places we call panic directly, and they are
> broken.
> 
> Use console_verbose like we do in the oops path to ensure a directly called
> panic will print a backtrace.
> 
> Signed-off-by: Anton Blanchard <anton@samba.org>

Looks good to me:
	Acked-by: Greg Kroah-Hartman <gregkh@suse.de>

thanks,

greg k-h

Re: [PATCH] panic: Call console_verbose in panic

[Andrew Morton]

On Tue, 11 May 2010 08:59:59 +1000
Anton Blanchard <anton@samba.org> wrote:

> 
> Most distros turn the console verbosity down and that means a backtrace after
> a panic never makes it to the console. I assume we haven't seen this because
> a panic is often preceeded by an oops which will have called console_verbose.
> There are however a lot of places we call panic directly, and they are
> broken.
> 
> Use console_verbose like we do in the oops path to ensure a directly called
> panic will print a backtrace.
> 
> Signed-off-by: Anton Blanchard <anton@samba.org>
> ---
> 
> Index: linux-2.6/kernel/panic.c
> ===================================================================
> --- linux-2.6.orig/kernel/panic.c	2010-05-09 09:13:06.000000000 +1000
> +++ linux-2.6/kernel/panic.c	2010-05-09 09:14:13.000000000 +1000
> @@ -87,6 +87,7 @@ NORET_TYPE void panic(const char * fmt, 
>  	 */
>  	preempt_disable();
>  
> +	console_verbose();
>  	bust_spinlocks(1);
>  	va_start(args, fmt);
>  	vsnprintf(buf, sizeof(buf), fmt, args);

hm, console_verbose() is interesting:

: static inline void console_verbose(void)
: {
: 	if (console_loglevel)
: 		console_loglevel = 15;
: }

so if someone has run console_silent():

: static inline void console_silent(void)
: {
: 	console_loglevel = 0;
: }

then console_verbose() doesn't work.


The sole caller of console_silent() is
arch/mn10300/kernel/mn10300-watchdog.c:watchdog_interrupt(), which
makes me wonder if mn10300 is doing something wrong or outdated?

Re: [PATCH] panic: Call console_verbose in panic

[David Howells]

Andrew Morton <akpm@linux-foundation.org> wrote:

> The sole caller of console_silent() is
> arch/mn10300/kernel/mn10300-watchdog.c:watchdog_interrupt(), which
> makes me wonder if mn10300 is doing something wrong or outdated?

The MN10300 code will have been copied from elsewhere, so it may well be
outdated.

David