From b79371604494ac0b30e2bcbeccd74e6135e6910d Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sun, 11 Sep 2022 00:28:17 +0200 Subject: [PATCH] kernel/panic: Add atomic write enforcement to warn/panic Invoke the atomic write enforcement functions for warn/panic to ensure that the information gets out to the consoles. For the panic case, add explicit intermediate atomic flush calls to ensure immediate flushing at important points. Otherwise the atomic flushing only occurs when dropping out of the elevated priority, which for panic may never happen. It is important to note that if there are any legacy consoles registered, they will be attempting to directly print from the printk-caller context, which may jeopardize the reliability of the atomic consoles. Optimally there should be no legacy consoles registered. Co-developed-by: John Ogness Signed-off-by: John Ogness Signed-off-by: Thomas Gleixner (Intel) Signed-off-by: Sebastian Andrzej Siewior --- kernel/panic.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/kernel/panic.c b/kernel/panic.c index 07239d4ad81e..09b40184ddea 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -275,6 +275,7 @@ static void panic_other_cpus_shutdown(bool crash_kexec) */ void panic(const char *fmt, ...) { + enum cons_prio prev_prio; static char buf[1024]; va_list args; long i, i_next = 0, len; @@ -322,6 +323,8 @@ void panic(const char *fmt, ...) if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu) panic_smp_self_stop(); + prev_prio = cons_atomic_enter(CONS_PRIO_PANIC); + console_verbose(); bust_spinlocks(1); va_start(args, fmt); @@ -382,6 +385,8 @@ void panic(const char *fmt, ...) if (_crash_kexec_post_notifiers) __crash_kexec(NULL); + cons_atomic_flush(NULL, true); + console_unblank(); /* @@ -406,6 +411,7 @@ void panic(const char *fmt, ...) * We can't use the "normal" timers since we just panicked. */ pr_emerg("Rebooting in %d seconds..\n", panic_timeout); + cons_atomic_flush(NULL, true); for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { touch_nmi_watchdog(); @@ -424,6 +430,7 @@ void panic(const char *fmt, ...) */ if (panic_reboot_mode != REBOOT_UNDEFINED) reboot_mode = panic_reboot_mode; + cons_atomic_flush(NULL, true); emergency_restart(); } #ifdef __sparc__ @@ -436,12 +443,16 @@ void panic(const char *fmt, ...) } #endif #if defined(CONFIG_S390) + cons_atomic_flush(NULL, true); disabled_wait(); #endif pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf); /* Do not scroll important messages printed above */ suppress_printk = 1; + + cons_atomic_exit(CONS_PRIO_PANIC, prev_prio); + local_irq_enable(); for (i = 0; ; i += PANIC_TIMER_STEP) { touch_softlockup_watchdog(); @@ -652,6 +663,10 @@ struct warn_args { void __warn(const char *file, int line, void *caller, unsigned taint, struct pt_regs *regs, struct warn_args *args) { + enum cons_prio prev_prio; + + prev_prio = cons_atomic_enter(CONS_PRIO_EMERGENCY); + disable_trace_on_warning(); if (file) @@ -682,6 +697,8 @@ void __warn(const char *file, int line, void *caller, unsigned taint, /* Just a warning, don't kill lockdep. */ add_taint(taint, LOCKDEP_STILL_OK); + + cons_atomic_exit(CONS_PRIO_EMERGENCY, prev_prio); } #ifdef CONFIG_BUG