v4.19.13 snapshot.
diff --git a/include/linux/ratelimit.h b/include/linux/ratelimit.h
new file mode 100644
index 0000000..8ddf79e
--- /dev/null
+++ b/include/linux/ratelimit.h
@@ -0,0 +1,113 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_RATELIMIT_H
+#define _LINUX_RATELIMIT_H
+
+#include <linux/param.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+
+#define DEFAULT_RATELIMIT_INTERVAL (5 * HZ)
+#define DEFAULT_RATELIMIT_BURST 10
+
+/* issue num suppressed message on exit */
+#define RATELIMIT_MSG_ON_RELEASE BIT(0)
+
+struct ratelimit_state {
+ raw_spinlock_t lock; /* protect the state */
+
+ int interval;
+ int burst;
+ int printed;
+ int missed;
+ unsigned long begin;
+ unsigned long flags;
+};
+
+#define RATELIMIT_STATE_INIT(name, interval_init, burst_init) { \
+ .lock = __RAW_SPIN_LOCK_UNLOCKED(name.lock), \
+ .interval = interval_init, \
+ .burst = burst_init, \
+ }
+
+#define RATELIMIT_STATE_INIT_DISABLED \
+ RATELIMIT_STATE_INIT(ratelimit_state, 0, DEFAULT_RATELIMIT_BURST)
+
+#define DEFINE_RATELIMIT_STATE(name, interval_init, burst_init) \
+ \
+ struct ratelimit_state name = \
+ RATELIMIT_STATE_INIT(name, interval_init, burst_init) \
+
+static inline void ratelimit_state_init(struct ratelimit_state *rs,
+ int interval, int burst)
+{
+ memset(rs, 0, sizeof(*rs));
+
+ raw_spin_lock_init(&rs->lock);
+ rs->interval = interval;
+ rs->burst = burst;
+}
+
+static inline void ratelimit_default_init(struct ratelimit_state *rs)
+{
+ return ratelimit_state_init(rs, DEFAULT_RATELIMIT_INTERVAL,
+ DEFAULT_RATELIMIT_BURST);
+}
+
+static inline void ratelimit_state_exit(struct ratelimit_state *rs)
+{
+ if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE))
+ return;
+
+ if (rs->missed) {
+ pr_warn("%s: %d output lines suppressed due to ratelimiting\n",
+ current->comm, rs->missed);
+ rs->missed = 0;
+ }
+}
+
+static inline void
+ratelimit_set_flags(struct ratelimit_state *rs, unsigned long flags)
+{
+ rs->flags = flags;
+}
+
+extern struct ratelimit_state printk_ratelimit_state;
+
+extern int ___ratelimit(struct ratelimit_state *rs, const char *func);
+#define __ratelimit(state) ___ratelimit(state, __func__)
+
+#ifdef CONFIG_PRINTK
+
+#define WARN_ON_RATELIMIT(condition, state) ({ \
+ bool __rtn_cond = !!(condition); \
+ WARN_ON(__rtn_cond && __ratelimit(state)); \
+ __rtn_cond; \
+})
+
+#define WARN_RATELIMIT(condition, format, ...) \
+({ \
+ static DEFINE_RATELIMIT_STATE(_rs, \
+ DEFAULT_RATELIMIT_INTERVAL, \
+ DEFAULT_RATELIMIT_BURST); \
+ int rtn = !!(condition); \
+ \
+ if (unlikely(rtn && __ratelimit(&_rs))) \
+ WARN(rtn, format, ##__VA_ARGS__); \
+ \
+ rtn; \
+})
+
+#else
+
+#define WARN_ON_RATELIMIT(condition, state) \
+ WARN_ON(condition)
+
+#define WARN_RATELIMIT(condition, format, ...) \
+({ \
+ int rtn = WARN(condition, format, ##__VA_ARGS__); \
+ rtn; \
+})
+
+#endif
+
+#endif /* _LINUX_RATELIMIT_H */