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From: John Ogness <john.ogness@linutronix.de>
To: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Josh Poimboeuf <jpoimboe@kernel.org>,
	Uros Bizjak <ubizjak@gmail.com>,
	Kefeng Wang <wangkefeng.wang@huawei.com>,
	Arnd Bergmann <arnd@arndb.de>
Subject: [PATCH printk v4 25/27] panic: Mark emergency section in oops
Date: Wed,  3 Apr 2024 00:17:27 +0206
Message-Id: <20240402221129.2613843-26-john.ogness@linutronix.de>
In-Reply-To: <20240402221129.2613843-1-john.ogness@linutronix.de>
References: <20240402221129.2613843-1-john.ogness@linutronix.de>
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Mark an emergency section beginning with oops_enter() until the
end of oops_exit(). In this section, the CPU will not perform
console output for the printk() calls. Instead, a flushing of the
console output is triggered when exiting the emergency section.

The very end of oops_exit() performs a kmsg_dump(). This is not
included in the emergency section because it is another
flushing mechanism that should occur after the consoles have
been triggered to flush.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
---
 kernel/panic.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/panic.c b/kernel/panic.c
index ee03193f9495..3754a2471b4f 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -634,6 +634,7 @@ bool oops_may_print(void)
  */
 void oops_enter(void)
 {
+	nbcon_cpu_emergency_enter();
 	tracing_off();
 	/* can't trust the integrity of the kernel anymore: */
 	debug_locks_off();
@@ -656,6 +657,7 @@ void oops_exit(void)
 {
 	do_oops_enter_exit();
 	print_oops_end_marker();
+	nbcon_cpu_emergency_exit();
 	kmsg_dump(KMSG_DUMP_OOPS);
 }
 
-- 
2.39.2