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-rw-r--r--kernel/printk.c43
1 files changed, 36 insertions, 7 deletions
diff --git a/kernel/printk.c b/kernel/printk.c
index 444b770c9595..8fe465ac008a 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -37,6 +37,8 @@
#include <linux/ratelimit.h>
#include <linux/kmsg_dump.h>
#include <linux/syslog.h>
+#include <linux/cpu.h>
+#include <linux/notifier.h>
#include <asm/uaccess.h>
@@ -985,6 +987,32 @@ void resume_console(void)
}
/**
+ * console_cpu_notify - print deferred console messages after CPU hotplug
+ * @self: notifier struct
+ * @action: CPU hotplug event
+ * @hcpu: unused
+ *
+ * If printk() is called from a CPU that is not online yet, the messages
+ * will be spooled but will not show up on the console. This function is
+ * called when a new CPU comes online (or fails to come up), and ensures
+ * that any such output gets printed.
+ */
+static int __cpuinit console_cpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu)
+{
+ switch (action) {
+ case CPU_ONLINE:
+ case CPU_DEAD:
+ case CPU_DYING:
+ case CPU_DOWN_FAILED:
+ case CPU_UP_CANCELED:
+ acquire_console_sem();
+ release_console_sem();
+ }
+ return NOTIFY_OK;
+}
+
+/**
* acquire_console_sem - lock the console system for exclusive use.
*
* Acquires a semaphore which guarantees that the caller has
@@ -1371,7 +1399,7 @@ int unregister_console(struct console *console)
}
EXPORT_SYMBOL(unregister_console);
-static int __init disable_boot_consoles(void)
+static int __init printk_late_init(void)
{
struct console *con;
@@ -1382,9 +1410,10 @@ static int __init disable_boot_consoles(void)
unregister_console(con);
}
}
+ hotcpu_notifier(console_cpu_notify, 0);
return 0;
}
-late_initcall(disable_boot_consoles);
+late_initcall(printk_late_init);
#if defined CONFIG_PRINTK
@@ -1520,9 +1549,9 @@ void kmsg_dump(enum kmsg_dump_reason reason)
chars = logged_chars;
spin_unlock_irqrestore(&logbuf_lock, flags);
- if (logged_chars > end) {
- s1 = log_buf + log_buf_len - logged_chars + end;
- l1 = logged_chars - end;
+ if (chars > end) {
+ s1 = log_buf + log_buf_len - chars + end;
+ l1 = chars - end;
s2 = log_buf;
l2 = end;
@@ -1530,8 +1559,8 @@ void kmsg_dump(enum kmsg_dump_reason reason)
s1 = "";
l1 = 0;
- s2 = log_buf + end - logged_chars;
- l2 = logged_chars;
+ s2 = log_buf + end - chars;
+ l2 = chars;
}
if (!spin_trylock_irqsave(&dump_list_lock, flags)) {