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Subject[PATCH RFC] [1/3] isolate ratelimit from printk.c for other use
This series include 3 patch, they need to be applied in order.
1) isolate ratelimit from printk.c
2) add WARN_ON_SECS macro
3) use WARN_ON_SECS macro in rcupreempt.h

Please give some comments and suggestions for improvement, thanks.

---

Due to the rcupreempt.h WARN_ON trigged, I got 2G syslog file. For some
serious complaining of kernel, we need repeat the warnings, so here I
isolate the ratelimit part of printk.c to a standalone file.

Signed-off-by: Dave Young <hidave.darkstar@gmail.com>

---
include/linux/kernel.h | 1
kernel/printk.c | 26 ------------------------
lib/Makefile | 2 -
lib/ratelimit.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 54 insertions(+), 26 deletions(-)

diff -uprN linux/include/linux/kernel.h linux.new/include/linux/kernel.h
--- linux/include/linux/kernel.h 2008-03-10 13:41:18.000000000 +0800
+++ linux.new/include/linux/kernel.h 2008-03-10 13:42:06.000000000 +0800
@@ -188,6 +188,7 @@ extern int log_buf_copy(char *dest, int
extern int printk_ratelimit_jiffies;
extern int printk_ratelimit_burst;
extern int printk_ratelimit(void);
+extern int __ratelimit(int ratelimit_jiffies, int ratelimit_burst);
extern int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst);
extern bool printk_timed_ratelimit(unsigned long *caller_jiffies,
unsigned int interval_msec);
diff -uprN linux/kernel/printk.c linux.new/kernel/printk.c
--- linux/kernel/printk.c 2008-03-10 13:41:37.000000000 +0800
+++ linux.new/kernel/printk.c 2008-03-10 13:42:19.000000000 +0800
@@ -1261,31 +1261,7 @@ void tty_write_message(struct tty_struct
*/
int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst)
{
- static DEFINE_SPINLOCK(ratelimit_lock);
- static unsigned toks = 10 * 5 * HZ;
- static unsigned long last_msg;
- static int missed;
- unsigned long flags;
- unsigned long now = jiffies;
-
- spin_lock_irqsave(&ratelimit_lock, flags);
- toks += now - last_msg;
- last_msg = now;
- if (toks > (ratelimit_burst * ratelimit_jiffies))
- toks = ratelimit_burst * ratelimit_jiffies;
- if (toks >= ratelimit_jiffies) {
- int lost = missed;
-
- missed = 0;
- toks -= ratelimit_jiffies;
- spin_unlock_irqrestore(&ratelimit_lock, flags);
- if (lost)
- printk(KERN_WARNING "printk: %d messages suppressed.\n", lost);
- return 1;
- }
- missed++;
- spin_unlock_irqrestore(&ratelimit_lock, flags);
- return 0;
+ return __ratelimit(ratelimit_jiffies, ratelimit_burst);
}
EXPORT_SYMBOL(__printk_ratelimit);

diff -uprN linux/lib/Makefile linux.new/lib/Makefile
--- linux/lib/Makefile 2008-03-10 13:43:57.000000000 +0800
+++ linux.new/lib/Makefile 2008-03-10 13:42:38.000000000 +0800
@@ -6,7 +6,7 @@ lib-y := ctype.o string.o vsprintf.o cmd
rbtree.o radix-tree.o dump_stack.o \
idr.o int_sqrt.o extable.o prio_tree.o \
sha1.o irq_regs.o reciprocal_div.o argv_split.o \
- proportions.o prio_heap.o
+ proportions.o prio_heap.o ratelimit.o

lib-$(CONFIG_MMU) += ioremap.o
lib-$(CONFIG_SMP) += cpumask.o
diff -uprN linux/lib/ratelimit.c linux.new/lib/ratelimit.c
--- linux/lib/ratelimit.c 1970-01-01 07:00:00.000000000 +0700
+++ linux.new/lib/ratelimit.c 2008-03-10 13:42:46.000000000 +0800
@@ -0,0 +1,51 @@
+/*
+ * ratelimit.c - Do something with rate limit.
+ *
+ * Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com>
+ *
+ * This file is released under the GPLv2.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+
+/*
+ * __ratelimit - rate limiting
+ * @ratelimit_jiffies: minimum time in jiffies between too callbacks
+ * @ratelimit_burst: number of callbacks we do before ratelimiting
+ *
+ * This enforces a rate limit: not more than @ratelimit_burst callbacks
+ * in every ratelimit_jiffies
+ */
+int __ratelimit(int ratelimit_jiffies, int ratelimit_burst)
+{
+ static DEFINE_SPINLOCK(ratelimit_lock);
+ static unsigned toks = 10 * 5 * HZ;
+ static unsigned long last_msg;
+ static int missed;
+ unsigned long flags;
+ unsigned long now = jiffies;
+
+ spin_lock_irqsave(&ratelimit_lock, flags);
+ toks += now - last_msg;
+ last_msg = now;
+ if (toks > (ratelimit_burst * ratelimit_jiffies))
+ toks = ratelimit_burst * ratelimit_jiffies;
+ if (toks >= ratelimit_jiffies) {
+ int lost = missed;
+
+ missed = 0;
+ toks -= ratelimit_jiffies;
+ spin_unlock_irqrestore(&ratelimit_lock, flags);
+ if (lost)
+ printk(KERN_WARNING "__ratelimit: %d messages"
+ " suppressed.\n", lost);
+ return 1;
+ }
+ missed++;
+ spin_unlock_irqrestore(&ratelimit_lock, flags);
+ return 0;
+}
+EXPORT_SYMBOL(__ratelimit);

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