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From:   Dmitry Safonov <dima@arista.com>
To:     linux-kernel@vger.kernel.org
Cc:     Dmitry Safonov <0x7f454c46@gmail.com>,
        Dmitry Safonov <dima@arista.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Ingo Molnar <mingo@kernel.org>, Jiri Slaby <jslaby@suse.com>,
        Petr Mladek <pmladek@suse.com>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
        Jonas Bonn <jonas@southpole.se>,
        Stafford Horne <shorne@gmail.com>,
        Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
        openrisc@lists.librecores.org
Subject: [PATCHv3 24/50] openrisc: Add show_stack_loglvl()
Date:   Sat, 18 Apr 2020 21:19:18 +0100
Message-Id: <20200418201944.482088-25-dima@arista.com>
In-Reply-To: <20200418201944.482088-1-dima@arista.com>
References: <20200418201944.482088-1-dima@arista.com>
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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: Jonas Bonn <jonas@southpole.se>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: openrisc@lists.librecores.org
[1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/T/#u
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 arch/openrisc/kernel/traps.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/arch/openrisc/kernel/traps.c b/arch/openrisc/kernel/traps.c
index c11aa2e17ce0..3b7978a22d68 100644
--- a/arch/openrisc/kernel/traps.c
+++ b/arch/openrisc/kernel/traps.c
@@ -41,18 +41,26 @@ unsigned long __user *lwa_addr;
 
 void print_trace(void *data, unsigned long addr, int reliable)
 {
-	pr_emerg("[<%p>] %s%pS\n", (void *) addr, reliable ? "" : "? ",
+	const char *loglvl = data;
+
+	printk("%s[<%p>] %s%pS\n", loglvl, (void *) addr, reliable ? "" : "? ",
 	       (void *) addr);
 }
 
 /* displays a short stack trace */
-void show_stack(struct task_struct *task, unsigned long *esp)
+void show_stack_loglvl(struct task_struct *task, unsigned long *esp,
+		const char *loglvl)
 {
 	if (esp == NULL)
 		esp = (unsigned long *)&esp;
 
-	pr_emerg("Call trace:\n");
-	unwind_stack(NULL, esp, print_trace);
+	printk("%sCall trace:\n", loglvl);
+	unwind_stack((void *)loglvl, esp, print_trace);
+}
+
+void show_stack(struct task_struct *task, unsigned long *esp)
+{
+	show_stack_loglvl(task, esp, KERN_EMERG);
 }
 
 void show_registers(struct pt_regs *regs)
-- 
2.26.0