1 files changed, 57 insertions, 0 deletions
diff --git a/lib/ratelimit.c b/lib/ratelimit.c
new file mode 100644
index 0000000..26187ed
--- /dev/null
+++ b/lib/ratelimit.c
@@ -0,0 +1,57 @@
+/*
+ * ratelimit.c - Do something with rate limit.
+ *
+ * Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com>
+ *
+ * 2008-05-01 rewrite the function and use a ratelimit_state data struct as
+ * parameter. Now every user can use their own standalone ratelimit_state.
+ *
+ * This file is released under the GPLv2.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+
+static DEFINE_SPINLOCK(ratelimit_lock);
+
+/*
+ * __ratelimit - rate limiting
+ * @rs: ratelimit_state data
+ *
+ * This enforces a rate limit: not more than @rs->ratelimit_burst callbacks
+ * in every @rs->ratelimit_jiffies
+ */
+int __ratelimit(struct ratelimit_state *rs)
+{
+	unsigned long flags;
+
+	if (!rs->interval)
+		return 1;
+
+	spin_lock_irqsave(&ratelimit_lock, flags);
+	if (!rs->begin)
+		rs->begin = jiffies;
+
+	if (time_is_before_jiffies(rs->begin + rs->interval)) {
+		if (rs->missed)
+			printk(KERN_WARNING "%s: %d callbacks suppressed\n",
+				__func__, rs->missed);
+		rs->begin = 0;
+		rs->printed = 0;
+		rs->missed = 0;
+	}
+	if (rs->burst && rs->burst > rs->printed)
+		goto print;
+
+	rs->missed++;
+	spin_unlock_irqrestore(&ratelimit_lock, flags);
+	return 0;
+
+print:
+	rs->printed++;
+	spin_unlock_irqrestore(&ratelimit_lock, flags);
+	return 1;
+}
+EXPORT_SYMBOL(__ratelimit);