diff options
| -rw-r--r-- | include/linux/printk.h | 2 | ||||
| -rw-r--r-- | kernel/kexec_core.c | 1 | ||||
| -rw-r--r-- | kernel/panic.c | 6 | ||||
| -rw-r--r-- | kernel/printk/internal.h | 2 | ||||
| -rw-r--r-- | kernel/printk/nmi.c | 39 | ||||
| -rw-r--r-- | kernel/printk/printk.c | 2 |
6 files changed, 49 insertions, 3 deletions
diff --git a/include/linux/printk.h b/include/linux/printk.h index 51dd6b8..f4da695 100644 --- a/include/linux/printk.h +++ b/include/linux/printk.h @@ -127,11 +127,13 @@ extern void printk_nmi_init(void); extern void printk_nmi_enter(void); extern void printk_nmi_exit(void); extern void printk_nmi_flush(void); +extern void printk_nmi_flush_on_panic(void); #else static inline void printk_nmi_init(void) { } static inline void printk_nmi_enter(void) { } static inline void printk_nmi_exit(void) { } static inline void printk_nmi_flush(void) { } +static inline void printk_nmi_flush_on_panic(void) { } #endif /* PRINTK_NMI */ #ifdef CONFIG_PRINTK diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index 1c03dfb..d5d4082 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -893,6 +893,7 @@ void crash_kexec(struct pt_regs *regs) old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu); if (old_cpu == PANIC_CPU_INVALID) { /* This is the 1st CPU which comes here, so go ahead. */ + printk_nmi_flush_on_panic(); __crash_kexec(regs); /* diff --git a/kernel/panic.c b/kernel/panic.c index 535c965..8aa7449 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -160,8 +160,10 @@ void panic(const char *fmt, ...) * * Bypass the panic_cpu check and call __crash_kexec directly. */ - if (!crash_kexec_post_notifiers) + if (!crash_kexec_post_notifiers) { + printk_nmi_flush_on_panic(); __crash_kexec(NULL); + } /* * Note smp_send_stop is the usual smp shutdown function, which @@ -176,6 +178,8 @@ void panic(const char *fmt, ...) */ atomic_notifier_call_chain(&panic_notifier_list, 0, buf); + /* Call flush even twice. It tries harder with a single online CPU */ + printk_nmi_flush_on_panic(); kmsg_dump(KMSG_DUMP_PANIC); /* diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h index 341bedc..7fd2838 100644 --- a/kernel/printk/internal.h +++ b/kernel/printk/internal.h @@ -22,6 +22,8 @@ int __printf(1, 0) vprintk_default(const char *fmt, va_list args); #ifdef CONFIG_PRINTK_NMI +extern raw_spinlock_t logbuf_lock; + /* * printk() could not take logbuf_lock in NMI context. Instead, * it temporary stores the strings into a per-CPU buffer. diff --git a/kernel/printk/nmi.c b/kernel/printk/nmi.c index bf08557..b69eb8a 100644 --- a/kernel/printk/nmi.c +++ b/kernel/printk/nmi.c @@ -17,6 +17,7 @@ #include <linux/preempt.h> #include <linux/spinlock.h> +#include <linux/debug_locks.h> #include <linux/smp.h> #include <linux/cpumask.h> #include <linux/irq_work.h> @@ -106,7 +107,16 @@ static void print_nmi_seq_line(struct nmi_seq_buf *s, int start, int end) { const char *buf = s->buffer + start; - printk("%.*s", (end - start) + 1, buf); + /* + * The buffers are flushed in NMI only on panic. The messages must + * go only into the ring buffer at this stage. Consoles will get + * explicitly called later when a crashdump is not generated. + */ + if (in_nmi()) + printk_deferred("%.*s", (end - start) + 1, buf); + else + printk("%.*s", (end - start) + 1, buf); + } /* @@ -194,6 +204,33 @@ void printk_nmi_flush(void) __printk_nmi_flush(&per_cpu(nmi_print_seq, cpu).work); } +/** + * printk_nmi_flush_on_panic - flush all per-cpu nmi buffers when the system + * goes down. + * + * Similar to printk_nmi_flush() but it can be called even in NMI context when + * the system goes down. It does the best effort to get NMI messages into + * the main ring buffer. + * + * Note that it could try harder when there is only one CPU online. + */ +void printk_nmi_flush_on_panic(void) +{ + /* + * Make sure that we could access the main ring buffer. + * Do not risk a double release when more CPUs are up. + */ + if (in_nmi() && raw_spin_is_locked(&logbuf_lock)) { + if (num_online_cpus() > 1) + return; + + debug_locks_off(); + raw_spin_lock_init(&logbuf_lock); + } + + printk_nmi_flush(); +} + void __init printk_nmi_init(void) { int cpu; diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index e38579d..60cdf63 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -245,7 +245,7 @@ __packed __aligned(4) * within the scheduler's rq lock. It must be released before calling * console_unlock() or anything else that might wake up a process. */ -static DEFINE_RAW_SPINLOCK(logbuf_lock); +DEFINE_RAW_SPINLOCK(logbuf_lock); #ifdef CONFIG_PRINTK DECLARE_WAIT_QUEUE_HEAD(log_wait); |
