ratelimit: Warn if ->interval or ->burst are negative

Currently, ___ratelimit() treats a negative ->interval or ->burst as
if it was zero, but this is an accident of the current implementation.
Therefore, splat in this case, which might have the benefit of detecting
use of uninitialized ratelimit_state structures on the one hand or easing
addition of new features on the other.

Link: https://lore.kernel.org/all/fbe93a52-365e-47fe-93a4-44a44547d601@paulmck-laptop/
Link: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Petr Mladek <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Kuniyuki Iwashima <[email protected]>
Cc: Mateusz Guzik <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: John Ogness <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>

Author: pmladek

lib/ratelimit.c

@@ -40,6 +40,7 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
 	 * says always limit.
 	 */
 	if (interval <= 0 || burst <= 0) {
+		WARN_ONCE(interval < 0 || burst < 0, "Negative interval (%d) or burst (%d): Uninitialized ratelimit_state structure?\n", interval, burst);
 		ret = interval == 0 || burst > 0;
 		if (!(READ_ONCE(rs->flags) & RATELIMIT_INITIALIZED) || (!interval && !burst) ||
 		    !raw_spin_trylock_irqsave(&rs->lock, flags)) {