[PATCH v5 18/21] ratelimit: Use nolock_ret restructuring to collapse common case code

[Paul E. McKenney]

Now that unlock_ret releases the lock, then falls into nolock_ret, which
handles ->missed based on the value of ret, the common-case lock-held
code can be collapsed into a single "if" statement with a single-statement
"then" clause.

Yes, we could go further and just assign the "if" condition to ret,
but in the immortal words of MSDOS, "Are you sure?".

Link: https://lore.kernel.org/all/fbe93a52-365e-47fe-93a4-44a44547d601@paulmck-laptop/
Link: https://lore.kernel.org/all/20250423115409.3425-1-spasswolf@xxxxxx/
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Cc: Mateusz Guzik <mjguzik@xxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: John Ogness <john.ogness@xxxxxxxxxxxxx>
Cc: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
---
 lib/ratelimit.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/lib/ratelimit.c b/lib/ratelimit.c
index bcda7c61fc6ff..dcc063af195eb 100644
--- a/lib/ratelimit.c
+++ b/lib/ratelimit.c
@@ -88,17 +88,10 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
 			}
 		}
 	}
-	if (burst) {
-		int n_left = atomic_read(&rs->rs_n_left);
 
-		/* The burst might have been taken by a parallel call. */
-
-		if (n_left > 0) {
-			n_left = atomic_dec_return(&rs->rs_n_left);
-			if (n_left >= 0)
-				ret = 1;
-		}
-	}
+	/* Note that the burst might be taken by a parallel call. */
+	if (burst && atomic_read(&rs->rs_n_left) > 0 && atomic_dec_return(&rs->rs_n_left) >= 0)
+		ret = 1;
 
 unlock_ret:
 	raw_spin_unlock_irqrestore(&rs->lock, flags);
-- 
2.40.1