diff options
| -rw-r--r-- | include/linux/printk.h | 5 | ||||
| -rw-r--r-- | init/main.c | 1 | ||||
| -rw-r--r-- | kernel/printk/internal.h | 5 | ||||
| -rw-r--r-- | kernel/printk/printk.c | 34 | ||||
| -rw-r--r-- | kernel/printk/printk_safe.c | 11 |
5 files changed, 40 insertions, 16 deletions
diff --git a/include/linux/printk.h b/include/linux/printk.h index 1e6108b8d15f..e061635e0409 100644 --- a/include/linux/printk.h +++ b/include/linux/printk.h @@ -202,7 +202,6 @@ __printf(1, 2) void dump_stack_set_arch_desc(const char *fmt, ...); void dump_stack_print_info(const char *log_lvl); void show_regs_print_info(const char *log_lvl); extern asmlinkage void dump_stack(void) __cold; -extern void printk_safe_init(void); extern void printk_safe_flush(void); extern void printk_safe_flush_on_panic(void); #else @@ -269,10 +268,6 @@ static inline void dump_stack(void) { } -static inline void printk_safe_init(void) -{ -} - static inline void printk_safe_flush(void) { } diff --git a/init/main.c b/init/main.c index e488213857e2..a48617f2e5e5 100644 --- a/init/main.c +++ b/init/main.c @@ -913,7 +913,6 @@ asmlinkage __visible void __init start_kernel(void) boot_init_stack_canary(); time_init(); - printk_safe_init(); perf_event_init(); profile_init(); call_function_init(); diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h index c8e6ab689d42..b2b0f526f249 100644 --- a/kernel/printk/internal.h +++ b/kernel/printk/internal.h @@ -23,6 +23,9 @@ __printf(1, 0) int vprintk_func(const char *fmt, va_list args); void __printk_safe_enter(void); void __printk_safe_exit(void); +void printk_safe_init(void); +bool printk_percpu_data_ready(void); + #define printk_safe_enter_irqsave(flags) \ do { \ local_irq_save(flags); \ @@ -64,4 +67,6 @@ __printf(1, 0) int vprintk_func(const char *fmt, va_list args) { return 0; } #define printk_safe_enter_irq() local_irq_disable() #define printk_safe_exit_irq() local_irq_enable() +static inline void printk_safe_init(void) { } +static inline bool printk_percpu_data_ready(void) { return false; } #endif /* CONFIG_PRINTK */ diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 633f41a11d75..9a9b6156270b 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -460,6 +460,18 @@ static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); static char *log_buf = __log_buf; static u32 log_buf_len = __LOG_BUF_LEN; +/* + * We cannot access per-CPU data (e.g. per-CPU flush irq_work) before + * per_cpu_areas are initialised. This variable is set to true when + * it's safe to access per-CPU data. + */ +static bool __printk_percpu_data_ready __read_mostly; + +bool printk_percpu_data_ready(void) +{ + return __printk_percpu_data_ready; +} + /* Return log buffer address */ char *log_buf_addr_get(void) { @@ -1146,12 +1158,28 @@ static void __init log_buf_add_cpu(void) static inline void log_buf_add_cpu(void) {} #endif /* CONFIG_SMP */ +static void __init set_percpu_data_ready(void) +{ + printk_safe_init(); + /* Make sure we set this flag only after printk_safe() init is done */ + barrier(); + __printk_percpu_data_ready = true; +} + void __init setup_log_buf(int early) { unsigned long flags; char *new_log_buf; unsigned int free; + /* + * Some archs call setup_log_buf() multiple times - first is very + * early, e.g. from setup_arch(), and second - when percpu_areas + * are initialised. + */ + if (!early) + set_percpu_data_ready(); + if (log_buf != __log_buf) return; @@ -2975,6 +3003,9 @@ static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = { void wake_up_klogd(void) { + if (!printk_percpu_data_ready()) + return; + preempt_disable(); if (waitqueue_active(&log_wait)) { this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP); @@ -2985,6 +3016,9 @@ void wake_up_klogd(void) void defer_console_output(void) { + if (!printk_percpu_data_ready()) + return; + preempt_disable(); __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c index b4045e782743..d9a659a686f3 100644 --- a/kernel/printk/printk_safe.c +++ b/kernel/printk/printk_safe.c @@ -27,7 +27,6 @@ * There are situations when we want to make sure that all buffers * were handled or when IRQs are blocked. */ -static int printk_safe_irq_ready __read_mostly; #define SAFE_LOG_BUF_LEN ((1 << CONFIG_PRINTK_SAFE_LOG_BUF_SHIFT) - \ sizeof(atomic_t) - \ @@ -51,7 +50,7 @@ static DEFINE_PER_CPU(struct printk_safe_seq_buf, nmi_print_seq); /* Get flushed in a more safe context. */ static void queue_flush_work(struct printk_safe_seq_buf *s) { - if (printk_safe_irq_ready) + if (printk_percpu_data_ready()) irq_work_queue(&s->work); } @@ -402,14 +401,6 @@ void __init printk_safe_init(void) #endif } - /* - * In the highly unlikely event that a NMI were to trigger at - * this moment. Make sure IRQ work is set up before this - * variable is set. - */ - barrier(); - printk_safe_irq_ready = 1; - /* Flush pending messages that did not have scheduled IRQ works. */ printk_safe_flush(); } |