linux-kernel - [PATCH v4 1/4] printk: Add panic_in

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Date:   Wed,  2 Feb 2022 09:18:18 -0800
From:   Stephen Brennan <stephen.s.brennan@...cle.com>
To:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Petr Mladek <pmladek@...e.com>
Cc:     linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
        John Ogness <john.ogness@...utronix.de>,
        Stephen Brennan <stephen.s.brennan@...cle.com>
Subject: [PATCH v4 1/4] printk: Add panic_in_progress helper

This will be used help avoid deadlocks during panics. Although it would
be better to include this in linux/panic.h, it would require that header
to include linux/atomic.h as well. On some architectures, this results
in a circular dependency as well. So instead add the helper directly to
printk.c.

Suggested-by: Petr Mladek <pmladek@...e.com>
Signed-off-by: Stephen Brennan <stephen.s.brennan@...cle.com>
---

Notes:
    v4: Move helper outside CONFIG_PRINTK section
    v3: Move the helper into printk.c due to circular include
    v2: Switch from macro to static inline function

 kernel/printk/printk.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 57b132b658e1..e3d986dd49a1 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -256,6 +256,11 @@ static void __up_console_sem(unsigned long ip)
 }
 #define up_console_sem() __up_console_sem(_RET_IP_)
 
+static bool panic_in_progress(void)
+{
+	return unlikely(atomic_read(&panic_cpu) != PANIC_CPU_INVALID);
+}
+
 /*
  * This is used for debugging the mess that is the VT code by
  * keeping track if we have the console semaphore held. It's
-- 
2.30.2