[PATCH 17/50] m68k: Add show_stack_loglvl()

[Dmitry Safonov <dima@arista.com>]

Currently, the log-level of show_stack() depends on a platform
realization. It creates situations where the headers are printed with
lower log level or higher than the stacktrace (depending on
a platform or user).

Furthermore, it forces the logic decision from user to an architecture
side. In result, some users as sysrq/kdb/etc are doing tricks with
temporary rising console_loglevel while printing their messages.
And in result it not only may print unwanted messages from other CPUs,
but also omit printing at all in the unlucky case where the printk()
was deferred.

Introducing log-level parameter and KERN_UNSUPPRESSED [1] seems
an easier approach than introducing more printk buffers.
Also, it will consolidate printings with headers.

Introduce show_stack_loglvl(), that eventually will substitute
show_stack().

Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: linux-m68k@lists.linux-m68k.org
[1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/T/#u
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 arch/m68k/kernel/traps.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c
index 344f93d36a9a..ffcc5ec4fac3 100644
--- a/arch/m68k/kernel/traps.c
+++ b/arch/m68k/kernel/traps.c
@@ -811,13 +811,13 @@ asmlinkage void buserr_c(struct frame *fp)
 
 static int kstack_depth_to_print = 48;
 
-void show_trace(unsigned long *stack)
+static void show_trace(unsigned long *stack, const char *loglvl)
 {
 	unsigned long *endstack;
 	unsigned long addr;
 	int i;
 
-	pr_info("Call Trace:");
+	printk("%sCall Trace:", loglvl);
 	addr = (unsigned long)stack + THREAD_SIZE - 1;
 	endstack = (unsigned long *)(addr & -THREAD_SIZE);
 	i = 0;
@@ -935,7 +935,8 @@ void show_registers(struct pt_regs *regs)
 	pr_cont("\n");
 }
 
-void show_stack(struct task_struct *task, unsigned long *stack)
+void show_stack_loglvl(struct task_struct *task, unsigned long *stack,
+		       const char *loglvl)
 {
 	unsigned long *p;
 	unsigned long *endstack;
@@ -949,7 +950,7 @@ void show_stack(struct task_struct *task, unsigned long *stack)
 	}
 	endstack = (unsigned long *)(((unsigned long)stack + THREAD_SIZE - 1) & -THREAD_SIZE);
 
-	pr_info("Stack from %08lx:", (unsigned long)stack);
+	printk("%sStack from %08lx:", loglvl, (unsigned long)stack);
 	p = stack;
 	for (i = 0; i < kstack_depth_to_print; i++) {
 		if (p + 1 > endstack)
@@ -959,7 +960,12 @@ void show_stack(struct task_struct *task, unsigned long *stack)
 		pr_cont(" %08lx", *p++);
 	}
 	pr_cont("\n");
-	show_trace(stack);
+	show_trace(stack, loglvl);
+}
+
+void show_stack(struct task_struct *task, unsigned long *stack)
+{
+	show_stack_loglvl(task, stack, KERN_INFO);
 }
 
 /*
-- 
2.23.0