diff options
Diffstat (limited to 'kernel/printk/printk.c')
| -rw-r--r-- | kernel/printk/printk.c | 34 |
1 files changed, 34 insertions, 0 deletions
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)); |