[PATCH 1/4] panic: Add new API is_being_panic()

[Xiaoming Ni]

Add is_being_panic() to check whether the system is in panic state.
Used to replace the global variable used to determine the panic status
in other features: hung_task ledtrig-activity ledtrig-heartbeat

Signed-off-by: Xiaoming Ni <nixiaoming@xxxxxxxxxx>
---
 include/linux/kernel.h | 1 +
 kernel/panic.c         | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index f7902d8c1048..3d6f344771c1 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -167,6 +167,7 @@ void __might_fault(const char *file, int line);
 static inline void might_fault(void) { }
 #endif
 
+extern bool is_being_panic(void);
 extern struct atomic_notifier_head panic_notifier_list;
 extern long (*panic_blink)(int state);
 __printf(1, 2)
diff --git a/kernel/panic.c b/kernel/panic.c
index 332736a72a58..3b6a487702b0 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -125,6 +125,12 @@ void __weak crash_smp_send_stop(void)
 
 atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
 
+bool is_being_panic(void)
+{
+	return (atomic_read(&panic_cpu) != PANIC_CPU_INVALID);
+}
+EXPORT_SYMBOL(is_being_panic);
+
 /*
  * A variant of panic() called from NMI context. We return if we've already
  * panicked on this CPU. If another CPU already panicked, loop in
-- 
2.27.0