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>
diff --git a/lib/ratelimit.c b/lib/ratelimit.c
new file mode 100644
index 0000000..485e304
--- /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);