From: "Paul E. McKenney" <paulmck@xxxxxxxxxx> Kernels built with CONFIG_PREEMPT_RT=y can lose significant console output and shutdown time, which hides shutdown-time RCU issues from rcutorture. Therefore, make pr_flush() public and invoke it after then last print in kernel_power_off(). [ paulmck: Apply John Ogness feedback. ] [ paulmck: Appy Sebastian Andrzej Siewior feedback. ] [ paulmck: Apply kernel test robot feedback. ] Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> Reviewed-by: John Ogness <john.ogness@xxxxxxxxxxxxx> Reviewed-by: Petr Mladek <pmladek@xxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/5f743488-dc2a-4f19-bdda-cf50b9314832@paulmck-laptop Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx> --- include/linux/printk.h | 6 ++++++ kernel/printk/printk.c | 4 +--- kernel/reboot.c | 1 + 3 files changed, 8 insertions(+), 3 deletions(-) diff --git a/include/linux/printk.h b/include/linux/printk.h index 4217a9f412b2..5b462029d03c 100644 --- a/include/linux/printk.h +++ b/include/linux/printk.h @@ -207,6 +207,7 @@ void printk_legacy_allow_panic_sync(void); extern bool nbcon_device_try_acquire(struct console *con); extern void nbcon_device_release(struct console *con); void nbcon_atomic_flush_unsafe(void); +bool pr_flush(int timeout_ms, bool reset_on_progress); #else static inline __printf(1, 0) int vprintk(const char *s, va_list args) @@ -315,6 +316,11 @@ static inline void nbcon_atomic_flush_unsafe(void) { } +static inline bool pr_flush(int timeout_ms, bool reset_on_progress) +{ + return true; +} + #endif bool this_cpu_in_panic(void); diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 07668433644b..057db78876cd 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2461,7 +2461,6 @@ asmlinkage __visible int _printk(const char *fmt, ...) } EXPORT_SYMBOL(_printk); -static bool pr_flush(int timeout_ms, bool reset_on_progress); static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress); #else /* CONFIG_PRINTK */ @@ -2474,7 +2473,6 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre static u64 syslog_seq; -static bool pr_flush(int timeout_ms, bool reset_on_progress) { return true; } static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress) { return true; } #endif /* CONFIG_PRINTK */ @@ -4466,7 +4464,7 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre * Context: Process context. May sleep while acquiring console lock. * Return: true if all usable printers are caught up. */ -static bool pr_flush(int timeout_ms, bool reset_on_progress) +bool pr_flush(int timeout_ms, bool reset_on_progress) { return __pr_flush(NULL, timeout_ms, reset_on_progress); } diff --git a/kernel/reboot.c b/kernel/reboot.c index b5a8569e5d81..41ab9e1ba357 100644 --- a/kernel/reboot.c +++ b/kernel/reboot.c @@ -704,6 +704,7 @@ void kernel_power_off(void) migrate_to_reboot_cpu(); syscore_shutdown(); pr_emerg("Power down\n"); + pr_flush(1000, true); kmsg_dump(KMSG_DUMP_SHUTDOWN); machine_power_off(); } -- 2.48.1
