From e755c4382a68ee8bd07e8d8db0f63d7ed306ed03 Mon Sep 17 00:00:00 2001 From: Chao Qin Date: Mon, 19 Jul 2021 10:26:50 +0800 Subject: [PATCH 016/166] printk: Enhance the condition check of msleep in pr_flush() 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 Signed-off-by: Lili Li Signed-off-by: Thomas Gleixner Reviewed-by: John Ogness Signed-off-by: John Ogness Signed-off-by: Thomas Gleixner 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(-) Index: linux-5.15.32-rt39/kernel/printk/printk.c =================================================================== --- linux-5.15.32-rt39.orig/kernel/printk/printk.c +++ linux-5.15.32-rt39/kernel/printk/printk.c @@ -3705,7 +3705,9 @@ 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);