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-rw-r--r--kernel/printk.c40
1 files changed, 37 insertions, 3 deletions
diff --git a/kernel/printk.c b/kernel/printk.c
index 0b3ea2c..b663c2c 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1216,13 +1216,27 @@ int is_console_locked(void)
return console_locked;
}
+/*
+ * Delayed printk facility, for scheduler-internal messages:
+ */
+#define PRINTK_BUF_SIZE 512
+
+#define PRINTK_PENDING_WAKEUP 0x01
+#define PRINTK_PENDING_SCHED 0x02
+
static DEFINE_PER_CPU(int, printk_pending);
+static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf);
void printk_tick(void)
{
if (__this_cpu_read(printk_pending)) {
- __this_cpu_write(printk_pending, 0);
- wake_up_interruptible(&log_wait);
+ int pending = __this_cpu_xchg(printk_pending, 0);
+ if (pending & PRINTK_PENDING_SCHED) {
+ char *buf = __get_cpu_var(printk_sched_buf);
+ printk(KERN_WARNING "[sched_delayed] %s", buf);
+ }
+ if (pending & PRINTK_PENDING_WAKEUP)
+ wake_up_interruptible(&log_wait);
}
}
@@ -1236,7 +1250,7 @@ int printk_needs_cpu(int cpu)
void wake_up_klogd(void)
{
if (waitqueue_active(&log_wait))
- this_cpu_write(printk_pending, 1);
+ this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
}
/**
@@ -1629,6 +1643,26 @@ late_initcall(printk_late_init);
#if defined CONFIG_PRINTK
+int printk_sched(const char *fmt, ...)
+{
+ unsigned long flags;
+ va_list args;
+ char *buf;
+ int r;
+
+ local_irq_save(flags);
+ buf = __get_cpu_var(printk_sched_buf);
+
+ va_start(args, fmt);
+ r = vsnprintf(buf, PRINTK_BUF_SIZE, fmt, args);
+ va_end(args);
+
+ __this_cpu_or(printk_pending, PRINTK_PENDING_SCHED);
+ local_irq_restore(flags);
+
+ return r;
+}
+
/*
* printk rate limiting, lifted from the networking subsystem.
*
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