ratelimit: Simplify common-case exit path

By making "ret" always be initialized, and moving the final call to
ratelimit_state_inc_miss() out from under the lock, we save a goto and
a couple lines of code.  This also saves a couple of lines of code from
the unconditional enable/disable slowpath.

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

@@ -33,7 +33,7 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
 	int interval = READ_ONCE(rs->interval);
 	int burst = READ_ONCE(rs->burst);
 	unsigned long flags;
-	int ret;
+	int ret = 0;
 
 	/*
 	 * Zero interval says never limit, otherwise, non-positive burst
@@ -51,8 +51,6 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
 
 		/* Force re-initialization once re-enabled. */
 		rs->flags &= ~RATELIMIT_INITIALIZED;
-		if (!ret)
-			ratelimit_state_inc_miss(rs);
 		goto unlock_ret;
 	}
 
@@ -110,19 +108,17 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
 
 		if (n_left > 0) {
 			n_left = atomic_dec_return(&rs->rs_n_left);
-			if (n_left >= 0) {
+			if (n_left >= 0)
 				ret = 1;
-				goto unlock_ret;
-			}
 		}
 	}
 
-	ratelimit_state_inc_miss(rs);
-	ret = 0;
-
 unlock_ret:
 	raw_spin_unlock_irqrestore(&rs->lock, flags);
 
+	if (!ret)
+		ratelimit_state_inc_miss(rs);
+
 	return ret;
 }
 EXPORT_SYMBOL(___ratelimit);