From: Daniel Drake <dsd@laptop.org>
Date: Wed, 20 Oct 2010 23:00:48 +0000 (-0700)
Subject: serial8250: ratelimit "too much work" error
X-Git-Tag: v2.6.37-rc1~155^2
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=cd3ecad19aea8debae9a48b53de2ec7a571f24e9

serial8250: ratelimit "too much work" error

Running a serial console, if too many kernel messages are generated within
a short time causing a lot of serial I/O, the 8250 driver will generate
another kernel message reporting this, which just adds to the I/O. It has
a cascading effect and quickly results the system being brought to its knees
by a flood of "too much work" messages.

Ratelimit the error message to avoid this.

[akpm@linux-foundation.org: use the superior printk_ratelimited()]
[akpm@linux-foundation.org: printk_ratelimited() needs ratelimit.h]
Signed-off-by: Daniel Drake <dsd@laptop.org>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 37f19a678c97..167c4a6ccbc3 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -31,6 +31,7 @@
 #include <linux/delay.h>
 #include <linux/platform_device.h>
 #include <linux/tty.h>
+#include <linux/ratelimit.h>
 #include <linux/tty_flip.h>
 #include <linux/serial_reg.h>
 #include <linux/serial_core.h>
@@ -1600,8 +1601,8 @@ static irqreturn_t serial8250_interrupt(int irq, void *dev_id)
 
 		if (l == i->head && pass_counter++ > PASS_LIMIT) {
 			/* If we hit this, we're dead. */
-			printk(KERN_ERR "serial8250: too much work for "
-				"irq%d\n", irq);
+			printk_ratelimited(KERN_ERR
+				"serial8250: too much work for irq%d\n", irq);
 			break;
 		}
 	} while (l != end);