---

yaml
---
r: 164669
b: refs/heads/master
c: af91322
h: refs/heads/master
i:
  164667: a20d4bc
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 3a3b6ed2235f2f619889dd6096e24b6d93bf3339
+refs/heads/master: af91322ef3f29ae4114e736e2a72e28b4d619cf9

trunk/Documentation/sysctl/kernel.txt

@@ -313,6 +313,14 @@ send before ratelimiting kicks in.
 
 ==============================================================
 
+printk_delay:
+
+Delay each printk message in printk_delay milliseconds
+
+Value from 0 - 10000 is allowed.
+
+==============================================================
+
 randomize-va-space:
 
 This option can be used to select the type of process address

trunk/include/linux/kernel.h

@@ -246,6 +246,8 @@ extern int printk_ratelimit(void);
 extern bool printk_timed_ratelimit(unsigned long *caller_jiffies,
 				   unsigned int interval_msec);
 
+extern int printk_delay_msec;
+
 /*
  * Print a one-time message (analogous to WARN_ONCE() et al):
  */

trunk/kernel/printk.c

@@ -653,6 +653,20 @@ static int recursion_bug;
 static int new_text_line = 1;
 static char printk_buf[1024];
 
+int printk_delay_msec __read_mostly;
+
+static inline void printk_delay(void)
+{
+	if (unlikely(printk_delay_msec)) {
+		int m = printk_delay_msec;
+
+		while (m--) {
+			mdelay(1);
+			touch_nmi_watchdog();
+		}
+	}
+}
+
 asmlinkage int vprintk(const char *fmt, va_list args)
 {
 	int printed_len = 0;
@@ -662,6 +676,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
 	char *p;
 
 	boot_delay_msec();
+	printk_delay();
 
 	preempt_disable();
 	/* This stops the holder of console_sem just where we want him */

trunk/kernel/sysctl.c

@@ -106,6 +106,9 @@ static int __maybe_unused one = 1;
 static int __maybe_unused two = 2;
 static unsigned long one_ul = 1;
 static int one_hundred = 100;
+#ifdef CONFIG_PRINTK
+static int ten_thousand = 10000;
+#endif
 
 /* this is needed for the proc_doulongvec_minmax of vm_dirty_bytes */
 static unsigned long dirty_bytes_min = 2 * PAGE_SIZE;
@@ -722,6 +725,17 @@ static struct ctl_table kern_table[] = {
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec,
 	},
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "printk_delay",
+		.data		= &printk_delay_msec,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec_minmax,
+		.strategy	= &sysctl_intvec,
+		.extra1		= &zero,
+		.extra2		= &ten_thousand,
+	},
 #endif
 	{
 		.ctl_name	= KERN_NGROUPS_MAX,