kdb: don't play with console_loglevel

Print the stack trace with KERN_EMERG - it should be always visible.

Playing with console_loglevel is a bad idea as there may be more messages
printed than wanted.  Also the stack trace might be not printed at all if
printk() was deferred and console_loglevel was raised back before the
trace got flushed.

Unfortunately, after rebasing on commit 2277b49 ("kdb: Fix stack
crawling on 'running' CPUs that aren't the master"), kdb_show_stack() uses
now kdb_dump_stack_on_cpu(), which for now won't be converted as it uses
dump_stack() instead of show_stack().

Convert for now the branch that uses show_stack() and remove
console_loglevel exercise from that case.

Signed-off-by: Dmitry Safonov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Douglas Anderson <[email protected]>
Acked-by: Daniel Thompson <[email protected]>
Cc: Jason Wessel <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

kernel/debug/kdb/kdb_bt.c

@@ -21,17 +21,18 @@
 
 static void kdb_show_stack(struct task_struct *p, void *addr)
 {
-	int old_lvl = console_loglevel;
-
-	console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
 	kdb_trap_printk++;
 
-	if (!addr && kdb_task_has_cpu(p))
+	if (!addr && kdb_task_has_cpu(p)) {
+		int old_lvl = console_loglevel;
+
+		console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
 		kdb_dump_stack_on_cpu(kdb_process_cpu(p));
-	else
-		show_stack(p, addr);
+		console_loglevel = old_lvl;
+	} else {
+		show_stack_loglvl(p, addr, KERN_EMERG);
+	}
 
-	console_loglevel = old_lvl;
 	kdb_trap_printk--;
 }