Merge tag 'sound-5.7-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai...

[linux-2.6-microblaze.git] / kernel / printk / printk.c

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 633f41a..9a9b615 100644 (file)
--- 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));