linux-kernel - [PATCH v3 16/20] ratelimit: Simplify common-case exit path

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Message-Id: <20250425002826.3431914-16-paulmck@kernel.org>
Date: Thu, 24 Apr 2025 17:28:22 -0700
From: "Paul E. McKenney" <paulmck@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: kernel-team@...a.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	Kuniyuki Iwashima <kuniyu@...zon.com>,
	Mateusz Guzik <mjguzik@...il.com>,
	Petr Mladek <pmladek@...e.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	John Ogness <john.ogness@...utronix.de>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Jon Pan-Doh <pandoh@...gle.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Karolina Stolarek <karolina.stolarek@...cle.com>,
	"Paul E. McKenney" <paulmck@...nel.org>
Subject: [PATCH v3 16/20] 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@...nel.org>
Cc: Petr Mladek <pmladek@...e.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Kuniyuki Iwashima <kuniyu@...zon.com>
Cc: Mateusz Guzik <mjguzik@...il.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: John Ogness <john.ogness@...utronix.de>
Cc: Sergey Senozhatsky <senozhatsky@...omium.org>
---
 lib/ratelimit.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/lib/ratelimit.c b/lib/ratelimit.c
index 63efb1191d71a..7511f737dc1e2 100644
--- a/lib/ratelimit.c
+++ b/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);
-- 
2.40.1