Fix printk_ratelimited()

printk_ratelimited was behind an #ifdef CONFIG_PRINTK, which we don't
define, so it was a complete noop - oops.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

4 files changed, 77 insertions, 5 deletions

diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h
index fe928265..c3f3e1f2 100644
--- a/include/linux/jiffies.h
+++ b/include/linux/jiffies.h
@@ -43,6 +43,8 @@
 	(time_after_eq64(a, b) && \
 	 time_before_eq64(a, c))
 
+#define time_is_before_jiffies(a) time_after(jiffies, a)
+
 #define HZ		1000
 
 static inline u64 jiffies_to_nsecs(const unsigned long j)
diff --git a/include/linux/printk.h b/include/linux/printk.h
index bc1619f7..df9c1920 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -5,6 +5,7 @@
 #define pr_fmt(fmt) fmt
 #endif
 
+#include <linux/compiler.h>
 #include <stdarg.h>
 #include <stdio.h>
 
@@ -169,7 +170,6 @@ static inline int scnprintf(char * buf, size_t size, const char * fmt, ...)
  * ratelimited messages with local ratelimit_state,
  * no local ratelimit_state used in the !PRINTK case
  */
-#ifdef CONFIG_PRINTK
 #define printk_ratelimited(fmt, ...)					\
 ({									\
 	static DEFINE_RATELIMIT_STATE(_rs,				\
@@ -179,10 +179,6 @@ static inline int scnprintf(char * buf, size_t size, const char * fmt, ...)
 	if (__ratelimit(&_rs))						\
 		printk(fmt, ##__VA_ARGS__);				\
 })
-#else
-#define printk_ratelimited(fmt, ...)					\
-	no_printk(fmt, ##__VA_ARGS__)
-#endif
 
 #define pr_emerg_ratelimited(fmt, ...)					\
 	printk_ratelimited(KERN_EMERG pr_fmt(fmt), ##__VA_ARGS__)
diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
index bd51188d..6c4a623c 100644
--- a/include/linux/spinlock.h
+++ b/include/linux/spinlock.h
@@ -15,6 +15,11 @@ static inline void raw_spin_lock_init(raw_spinlock_t *lock)
 	pthread_mutex_init(&lock->lock, NULL);
 }
 
+static inline bool raw_spin_trylock(raw_spinlock_t *lock)
+{
+	return !pthread_mutex_trylock(&lock->lock);
+}
+
 static inline void raw_spin_lock(raw_spinlock_t *lock)
 {
 	pthread_mutex_lock(&lock->lock);
diff --git a/linux/ratelimit.c b/linux/ratelimit.c
new file mode 100644
index 00000000..21a6d6c8
--- /dev/null
+++ b/linux/ratelimit.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * 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.
+ */
+
+#include <linux/ratelimit.h>
+#include <linux/jiffies.h>
+#include <linux/export.h>
+
+/*
+ * __ratelimit - rate limiting
+ * @rs: ratelimit_state data
+ * @func: name of calling function
+ *
+ * This enforces a rate limit: not more than @rs->burst callbacks
+ * in every @rs->interval
+ *
+ * RETURNS:
+ * 0 means callbacks will be suppressed.
+ * 1 means go ahead and do it.
+ */
+int ___ratelimit(struct ratelimit_state *rs, const char *func)
+{
+	int ret;
+
+	if (!rs->interval)
+		return 1;
+
+	/*
+	 * If we contend on this state's lock then almost
+	 * by definition we are too busy to print a message,
+	 * in addition to the one that will be printed by
+	 * the entity that is holding the lock already:
+	 */
+	if (!raw_spin_trylock(&rs->lock))
+		return 0;
+
+	if (!rs->begin)
+		rs->begin = jiffies;
+
+	if (time_is_before_jiffies(rs->begin + rs->interval)) {
+		if (rs->missed) {
+			if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) {
+				printk(KERN_WARNING
+				       "%s: %d callbacks suppressed\n",
+				       func, rs->missed);
+				rs->missed = 0;
+			}
+		}
+		rs->begin   = jiffies;
+		rs->printed = 0;
+	}
+	if (rs->burst && rs->burst > rs->printed) {
+		rs->printed++;
+		ret = 1;
+	} else {
+		rs->missed++;
+		ret = 0;
+	}
+	raw_spin_unlock(&rs->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(___ratelimit);