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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Thu, 20 Jun 2024 11:21:13 +0200
Subject: [PATCH] prinkt/nbcon: Add a scheduling point to nbcon_kthread_func().
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.10/older/patches-6.10.2-rt14.tar.xz
Constant printing can lead to a CPU hog in nbcon_kthread_func(). The
context is preemptible but on !PREEMPT kernels there is no explicit
preemption point which leads softlockup warnings.
Add an explicit preemption point in nbcon_kthread_func().
Reported-by: Derek Barbosa <debarbos@redhat.com>
Link: https://lore.kernel.org/ZnHF5j1DUDjN1kkq@debarbos-thinkpadt14sgen2i.remote.csb
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Acked-by: Andrew Halaney <ahalaney@redhat.com>
Tested-by: Andrew Halaney <ahalaney@redhat.com>
Acked-by: Derek Barbosa <debarbos@redhat.com>
Tested-by: Derek Barbosa <debarbos@redhat.com>
Link: https://lore.kernel.org/r/20240620094300.YJlW043f@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/printk/nbcon.c | 1 +
1 file changed, 1 insertion(+)
--- a/kernel/printk/nbcon.c
+++ b/kernel/printk/nbcon.c
@@ -1119,6 +1119,7 @@ static int nbcon_kthread_func(void *__co
}
console_srcu_read_unlock(cookie);
+ cond_resched();
} while (backlog);
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