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From: chao.qin@intel.com
To: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org,
	bigeasy@linutronix.de, tglx@linutronix.de,
	john.ogness@linutronix.de, rostedt@goodmis.org
Cc: mgross@linux.intel.com, paul.mei@intel.com, lili.li@intel.com
Subject: [PREEMPT_RT][PATCH] printk: Enhance the condition check of msleep in pr_flush()
Date: Mon, 19 Jul 2021 10:26:50 +0800	[thread overview]
Message-ID: <20210719022649.3444072-1-chao.qin@intel.com> (raw)

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: 63cf1e4b564a ("printk: add pr_flush()")

Signed-off-by: Chao Qin <chao.qin@intel.com>
Signed-off-by: Lili Li <lili.li@intel.com>
---
 kernel/printk/printk.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 209d2392f0d8..a9b3afbdac39 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3620,7 +3620,8 @@ bool pr_flush(int timeout_ms, bool reset_on_progress)
 	u64 diff;
 	u64 seq;
 
-	may_sleep = (preemptible() && !in_softirq());
+	may_sleep = (preemptible() && !in_softirq()
+			&& (system_state >= SYSTEM_RUNNING));
 
 	seq = prb_next_seq(prb);
 

base-commit: 7e175e6b59975c8901ad370f7818937f68de45c1
-- 
2.25.1


             reply	other threads:[~2021-07-19  2:33 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-19  2:26 chao.qin [this message]
2021-07-19 14:55 ` John Ogness
2021-07-30 14:01   ` Sebastian Andrzej Siewior
2021-07-30 14:46     ` John Ogness
2021-08-02  6:08       ` Qin, Chao
2021-08-02  6:48       ` Sebastian Andrzej Siewior
2021-07-20 11:55 ` Joe Perches
2021-07-20 14:03   ` John Ogness
2021-07-21  1:42     ` Qin, Chao
2021-08-05  3:01     ` Qin, Chao
2021-08-05 12:21       ` John Ogness
2021-08-05 16:12         ` Steven Rostedt
2021-08-06 18:34           ` Steven Rostedt

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