isolate ratelimit from printk.c for other use

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>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 54 insertions, 26 deletions

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 28caa53dd1f7..ad5d05efcd1a 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -188,6 +188,7 @@ extern int log_buf_copy(char *dest, int idx, int len);
 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 --git a/kernel/printk.c b/kernel/printk.c
index bdd4ea8c3f2b..d3f9c0f788bf 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1287,31 +1287,7 @@ void tty_write_message(struct tty_struct *tty, char *msg)
  */
 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 --git a/lib/Makefile b/lib/Makefile
index 2d7001b7f5a4..0ae4eb047aac 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -6,7 +6,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
          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 --git a/lib/ratelimit.c b/lib/ratelimit.c
new file mode 100644
index 000000000000..485e3040dcd4
--- /dev/null
+++ b/lib/ratelimit.c
@@ -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 two 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 "%s: %d messages suppressed\n",
+                                __func__, lost);
+                return 1;
+        }
+        missed++;
+        spin_unlock_irqrestore(&ratelimit_lock, flags);
+        return 0;
+}
+EXPORT_SYMBOL(__ratelimit);