ratelimit: Use nolock_ret label to collapse lock-failure code

Now that we have a nolock_ret label that handles ->missed correctly
based on the value of ret, we can eliminate a local variable and collapse
several "if" statements on the lock-acquisition-failure code path.

Link: https://lore.kernel.org/all/fbe93a52-365e-47fe-93a4-44a44547d601@paulmck-laptop/
Link: https://lore.kernel.org/all/20250423115409.3425-1-spasswolf@web.de/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kuniyuki Iwashima <kuniyu@amazon.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>

Author: paulmckrcu

lib/ratelimit.c

@@ -58,20 +58,10 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
 	 * the current lock owner is just about to reset it.
 	 */
 	if (!raw_spin_trylock_irqsave(&rs->lock, flags)) {
-		unsigned int rs_flags = READ_ONCE(rs->flags);
-
-		if (rs_flags & RATELIMIT_INITIALIZED && burst) {
-			int n_left = atomic_read(&rs->rs_n_left);
-
-			if (n_left <= 0)
-				return 0;
-			n_left = atomic_dec_return(&rs->rs_n_left);
-			if (n_left >= 0)
-				return 1;
-		}
-
-		ratelimit_state_inc_miss(rs);
-		return 0;
+		if (READ_ONCE(rs->flags) & RATELIMIT_INITIALIZED && burst &&
+		    atomic_read(&rs->rs_n_left) > 0 && atomic_dec_return(&rs->rs_n_left) >= 0)
+			ret = 1;
+		goto nolock_ret;
 	}
 
 	if (!(rs->flags & RATELIMIT_INITIALIZED)) {