[PATCH 1/1] kernel: panic: display reason at end + pr_emerg

[PATCH 1/1] kernel: panic: display reason at end + pr_emerg

[Fabian Frederick]

Currently, booting without initrd specified on 80x25 screen
gives a call trace followed by atkbd : Spurious ACK.
Original message ("VFS: Unable to mount root fs") is not available.
Of course this could happen in other situations...

-This patch displays panic reason after call trace which could help
lot of people even if it's not the very last line on screen.

-Converting all panic.c printk(KERN_EMERG to pr_emerg(

Signed-off-by: Fabian Frederick <fabf@skynet.be>
---
 kernel/panic.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/panic.c b/kernel/panic.c
index 6d63003..b71d520 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -100,7 +100,7 @@ void panic(const char *fmt, ...)
 	va_start(args, fmt);
 	vsnprintf(buf, sizeof(buf), fmt, args);
 	va_end(args);
-	printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
+	pr_emerg("Kernel panic - not syncing: %s\n", buf);
 #ifdef CONFIG_DEBUG_BUGVERBOSE
 	/*
 	 * Avoid nested stack-dumping if a panic occurs during oops processing
@@ -141,7 +141,7 @@ void panic(const char *fmt, ...)
 		 * Delay timeout seconds before rebooting the machine.
 		 * We can't use the "normal" timers since we just panicked.
 		 */
-		printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
+		pr_emerg("Rebooting in %d seconds..", panic_timeout);
 
 		for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
 			touch_nmi_watchdog();
@@ -165,7 +165,7 @@ void panic(const char *fmt, ...)
 		extern int stop_a_enabled;
 		/* Make sure the user can actually press Stop-A (L1-A) */
 		stop_a_enabled = 1;
-		printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
+		pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
 	}
 #endif
 #if defined(CONFIG_S390)
@@ -176,6 +176,7 @@ void panic(const char *fmt, ...)
 		disabled_wait(caller);
 	}
 #endif
+	pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
 	local_irq_enable();
 	for (i = 0; ; i += PANIC_TIMER_STEP) {
 		touch_softlockup_watchdog();
-- 
1.8.1.4

Re: [PATCH 1/1] kernel: panic: display reason at end + pr_emerg

[Andrew Morton]

On Sat, 8 Feb 2014 15:45:22 +0800 Fabian Frederick <fabf@skynet.be> wrote:

> Currently, booting without initrd specified on 80x25 screen
> gives a call trace followed by atkbd : Spurious ACK.
> Original message ("VFS: Unable to mount root fs") is not available.
> Of course this could happen in other situations...
> 
> -This patch displays panic reason after call trace which could help
> lot of people even if it's not the very last line on screen.

Fair enough.  Hate it when that happens!

> -Converting all panic.c printk(KERN_EMERG to pr_emerg(

You missed a couple.

--- a/kernel/panic.c~kernel-panicc-display-reason-at-end-pr_emerg-fix
+++ a/kernel/panic.c
@@ -275,8 +275,7 @@ unsigned long get_taint(void)
 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
 {
 	if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
-		printk(KERN_WARNING
-		       "Disabling lock debugging due to kernel taint\n");
+		pr_warn("Disabling lock debugging due to kernel taint\n");
 
 	set_bit(flag, &tainted_mask);
 }
@@ -381,8 +380,7 @@ late_initcall(init_oops_id);
 void print_oops_end_marker(void)
 {
 	init_oops_id();
-	printk(KERN_WARNING "---[ end trace %016llx ]---\n",
-		(unsigned long long)oops_id);
+	pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
 }
 
 /*
_

Re: [PATCH 1/1] kernel: panic: display reason at end + pr_emerg

[Fabian Frederick]

On Tue, 11 Feb 2014 15:34:45 -0800
Andrew Morton <akpm@linux-foundation.org> wrote:

> On Sat, 8 Feb 2014 15:45:22 +0800 Fabian Frederick <fabf@skynet.be> wrote:
> 
> > Currently, booting without initrd specified on 80x25 screen
> > gives a call trace followed by atkbd : Spurious ACK.
> > Original message ("VFS: Unable to mount root fs") is not available.
> > Of course this could happen in other situations...
> > 
> > -This patch displays panic reason after call trace which could help
> > lot of people even if it's not the very last line on screen.
> 
> Fair enough.  Hate it when that happens!
I was sure I was not the only one :)

> 
> > -Converting all panic.c printk(KERN_EMERG to pr_emerg(
> 
> You missed a couple.
Thanks a lot for addition and patch fix.
What a pleasure to see such professionalism !

> 
> --- a/kernel/panic.c~kernel-panicc-display-reason-at-end-pr_emerg-fix
> +++ a/kernel/panic.c
> @@ -275,8 +275,7 @@ unsigned long get_taint(void)
>  void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
>  {
>  	if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
> -		printk(KERN_WARNING
> -		       "Disabling lock debugging due to kernel taint\n");
> +		pr_warn("Disabling lock debugging due to kernel taint\n");
>  
>  	set_bit(flag, &tainted_mask);
>  }
> @@ -381,8 +380,7 @@ late_initcall(init_oops_id);
>  void print_oops_end_marker(void)
>  {
>  	init_oops_id();
> -	printk(KERN_WARNING "---[ end trace %016llx ]---\n",
> -		(unsigned long long)oops_id);
> +	pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
>  }
>  
>  /*
> _
>