sh: add show_stack_loglvl()

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().

[1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/T/#u

Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: http://lkml.kernel.org/r/20200418201944.482088-34-dima@arista.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/sh/kernel/dumpstack.c b/arch/sh/kernel/dumpstack.c
index d488a47a1f0fcf45bb69f0f08bcbdd6cb1a1fd9a..cc51e9d74667486e91d646180eb8dac646068a7e 100644 (file)
--- a/arch/sh/kernel/dumpstack.c
+++ b/arch/sh/kernel/dumpstack.c
@@ -144,7 +144,8 @@ void show_trace(struct task_struct *tsk, unsigned long *sp,
        debug_show_held_locks(tsk);
 }
 
-void show_stack(struct task_struct *tsk, unsigned long *sp)
+void show_stack_loglvl(struct task_struct *tsk, unsigned long *sp,
+                      const char *loglvl)
 {
        unsigned long stack;
 
@@ -156,7 +157,12 @@ void show_stack(struct task_struct *tsk, unsigned long *sp)
                sp = (unsigned long *)tsk->thread.sp;
 
        stack = (unsigned long)sp;
-       dump_mem("Stack: ", KERN_DEFAULT, stack, THREAD_SIZE +
+       dump_mem("Stack: ", loglvl, stack, THREAD_SIZE +
                 (unsigned long)task_stack_page(tsk));
-       show_trace(tsk, sp, NULL, KERN_DEFAULT);
+       show_trace(tsk, sp, NULL, loglvl);
+}
+
+void show_stack(struct task_struct *task, unsigned long *sp)
+{
+       show_stack_loglvl(task, sp, KERN_DEFAULT);
 }