[PATCH printk v5 28/30] panic: Mark emergency section in oops

John Ogness
2024-05-02T21:38:56Z

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>
Reviewed-by: Petr Mladek <pmladek@suse.com>
---
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