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Subject: printk: Enhance the condition check of msleep in pr_flush()
From: Chao Qin <chao.qin@intel.com>
Date: Mon Jul 19 10:26:50 2021 +0800
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.15/older/patches-5.15.3-rt21.tar.xz
From: Chao Qin <chao.qin@intel.com>
There is msleep in pr_flush(). If call WARN() in the early boot
stage such as in early_initcall, pr_flush() will run into msleep
when process scheduler is not ready yet. And then the system will
sleep forever.
Before the system_state is SYSTEM_RUNNING, make sure DO NOT sleep
in pr_flush().
Fixes: c0b395bd0fe3("printk: add pr_flush()")
Signed-off-by: Chao Qin <chao.qin@intel.com>
Signed-off-by: Lili Li <lili.li@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/lkml/20210719022649.3444072-1-chao.qin@intel.com
---
kernel/printk/printk.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
---
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3649,7 +3649,9 @@ bool pr_flush(int timeout_ms, bool reset
u64 diff;
u64 seq;
- may_sleep = (preemptible() && !in_softirq());
+ may_sleep = (preemptible() &&
+ !in_softirq() &&
+ system_state >= SYSTEM_RUNNING);
seq = prb_next_seq(prb);
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