linux-kernel - [PATCH 5.10 060/238] printk: Add panic_in

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Date: Sun, 24 Mar 2024 19:37:28 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Stephen Brennan <stephen.s.brennan@...cle.com>,
	Petr Mladek <pmladek@...e.com>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 060/238] printk: Add panic_in_progress helper

From: Stephen Brennan <stephen.s.brennan@...cle.com>

[ Upstream commit 77498617857f68496b360081dde1a492d40c28b2 ]

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>
Reviewed-by: Petr Mladek <pmladek@...e.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@...omium.org>
Signed-off-by: Petr Mladek <pmladek@...e.com>
Link: https://lore.kernel.org/r/20220202171821.179394-2-stephen.s.brennan@oracle.com
Stable-dep-of: d04d5882cd67 ("printk: Disable passing console lock owner completely during panic()")
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/printk/printk.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 17a310dcb6d96..94af80b7fa9b5 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -258,6 +258,11 @@ 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
-- 
2.43.0