linux-kernel - [PATCH v2 1/4] panic: Add panic_in

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Message-Id: <20220126230236.750229-2-stephen.s.brennan@oracle.com>
Date:   Wed, 26 Jan 2022 15:02:33 -0800
From:   Stephen Brennan <stephen.s.brennan@...cle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Steven Rostedt <rostedt@...dmis.org>,
        Stephen Brennan <stephen.s.brennan@...cle.com>,
        Sebastian Reichel <sre@...nel.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        John Ogness <john.ogness@...utronix.de>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Luis Chamberlain <mcgrof@...nel.org>,
        linux-kernel@...r.kernel.org, Petr Mladek <pmladek@...e.com>
Subject: [PATCH v2 1/4] panic: Add panic_in_progress helper

This helper will be used in printk code to avoid deadlocks during
panic().

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

Notes:
    v2: Switch to static inline function

 include/linux/panic.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/panic.h b/include/linux/panic.h
index f5844908a089..1022ec930d34 100644
--- a/include/linux/panic.h
+++ b/include/linux/panic.h
@@ -4,6 +4,7 @@
 
 #include <linux/compiler_attributes.h>
 #include <linux/types.h>
+#include <linux/atomic.h>
 
 struct pt_regs;
 
@@ -45,6 +46,11 @@ extern bool crash_kexec_post_notifiers;
 extern atomic_t panic_cpu;
 #define PANIC_CPU_INVALID	-1
 
+static inline bool panic_in_progress(void)
+{
+	return unlikely(atomic_read(&panic_cpu) != PANIC_CPU_INVALID);
+}
+
 /*
  * Only to be used by arch init code. If the user over-wrote the default
  * CONFIG_PANIC_TIMEOUT, honor it.
-- 
2.30.2