1 files changed, 125 insertions, 2 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
index 8451dfc31d25..a30fe33de395 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -22,6 +22,8 @@
 #include <linux/tty_driver.h>
 #include <linux/console.h>
 #include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/nmi.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/interrupt.h>                    /* For in_interrupt() */
@@ -162,6 +164,113 @@ out:
 
 __setup("log_buf_len=", log_buf_len_setup);
 
+#ifdef CONFIG_BOOT_PRINTK_DELAY
+
+static unsigned int boot_delay; /* msecs delay after each printk during bootup */
+static unsigned long long printk_delay_msec; /* per msec, based on boot_delay */
+
+static int __init boot_delay_setup(char *str)
+{
+        unsigned long lpj;
+        unsigned long long loops_per_msec;
+
+        lpj = preset_lpj ? preset_lpj : 1000000;        /* some guess */
+        loops_per_msec = (unsigned long long)lpj / 1000 * HZ;
+
+        get_option(&str, &boot_delay);
+        if (boot_delay > 10 * 1000)
+                boot_delay = 0;
+
+        printk_delay_msec = loops_per_msec;
+        printk(KERN_DEBUG "boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
+                "HZ: %d, printk_delay_msec: %llu\n",
+                boot_delay, preset_lpj, lpj, HZ, printk_delay_msec);
+        return 1;
+}
+__setup("boot_delay=", boot_delay_setup);
+
+static void boot_delay_msec(void)
+{
+        unsigned long long k;
+        unsigned long timeout;
+
+        if (boot_delay == 0 || system_state != SYSTEM_BOOTING)
+                return;
+
+        k = (unsigned long long)printk_delay_msec * boot_delay;
+
+        timeout = jiffies + msecs_to_jiffies(boot_delay);
+        while (k) {
+                k--;
+                cpu_relax();
+                /*
+                 * use (volatile) jiffies to prevent
+                 * compiler reduction; loop termination via jiffies
+                 * is secondary and may or may not happen.
+                 */
+                if (time_after(jiffies, timeout))
+                        break;
+                touch_nmi_watchdog();
+        }
+}
+#else
+static inline void boot_delay_msec(void)
+{
+}
+#endif
+
+/*
+ * Return the number of unread characters in the log buffer.
+ */
+int log_buf_get_len(void)
+{
+        return logged_chars;
+}
+
+/*
+ * Copy a range of characters from the log buffer.
+ */
+int log_buf_copy(char *dest, int idx, int len)
+{
+        int ret, max;
+        bool took_lock = false;
+
+        if (!oops_in_progress) {
+                spin_lock_irq(&logbuf_lock);
+                took_lock = true;
+        }
+
+        max = log_buf_get_len();
+        if (idx < 0 || idx >= max) {
+                ret = -1;
+        } else {
+                if (len > max)
+                        len = max;
+                ret = len;
+                idx += (log_end - max);
+                while (len-- > 0)
+                        dest[len] = LOG_BUF(idx + len);
+        }
+
+        if (took_lock)
+                spin_unlock_irq(&logbuf_lock);
+
+        return ret;
+}
+
+/*
+ * Extract a single character from the log buffer.
+ */
+int log_buf_read(int idx)
+{
+        char ret;
+
+        if (log_buf_copy(&ret, idx, 1) == 1)
+                return ret;
+        else
+                return -1;
+}
+
 /*
  * Commands to do_syslog:
  *
@@ -527,6 +636,8 @@ asmlinkage int vprintk(const char *fmt, va_list args)
         static char printk_buf[1024];
         static int log_level_unknown = 1;
 
+        boot_delay_msec();
+
         preempt_disable();
         if (unlikely(oops_in_progress) && printk_cpu == smp_processor_id())
                 /* If a crash is occurring during printk() on this CPU,
@@ -751,7 +862,16 @@ int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, cha
         return -1;
 }
 
-#ifndef CONFIG_DISABLE_CONSOLE_SUSPEND
+int console_suspend_enabled = 1;
+EXPORT_SYMBOL(console_suspend_enabled);
+
+static int __init console_suspend_disable(char *str)
+{
+        console_suspend_enabled = 0;
+        return 1;
+}
+__setup("no_console_suspend", console_suspend_disable);
+
 /**
  * suspend_console - suspend the console subsystem
  *
@@ -759,6 +879,8 @@ int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, cha
  */
 void suspend_console(void)
 {
+        if (!console_suspend_enabled)
+                return;
         printk("Suspending console(s)\n");
         acquire_console_sem();
         console_suspended = 1;
@@ -766,10 +888,11 @@ void suspend_console(void)
 
 void resume_console(void)
 {
+        if (!console_suspend_enabled)
+                return;
         console_suspended = 0;
         release_console_sem();
 }
-#endif /* CONFIG_DISABLE_CONSOLE_SUSPEND */
 
 /**
  * acquire_console_sem - lock the console system for exclusive use.