linux-kernel - [PATCH v3 18/20] ratelimit: Use nolock_ret label to collapse lock-failure code

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Message-Id: <20250425002826.3431914-18-paulmck@kernel.org>
Date: Thu, 24 Apr 2025 17:28:24 -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 18/20] 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@...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 | 18 ++++--------------
 1 file changed, 4 insertions(+), 14 deletions(-)

diff --git a/lib/ratelimit.c b/lib/ratelimit.c
index 7b075654e23ac..7bbc270b88e21 100644
--- a/lib/ratelimit.c
+++ b/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)) {
-- 
2.40.1