linux-kernel - [PATCH v1 3/4] cpuidle: teo: Reorder candidate state index checks

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Message-ID: <8476650.T7Z3S40VBb@rjwysocki.net>
Date: Fri, 10 Jan 2025 13:55:29 +0100
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
 Daniel Lezcano <daniel.lezcano@...aro.org>,
 Christian Loehle <christian.loehle@....com>,
 Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>
Subject: [PATCH v1 3/4] cpuidle: teo: Reorder candidate state index checks

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Since constraint_idx may be 0, the candidate state index may change to 0
after assinging constraint_idx to it, so first check if it is greater
than constraint_idx (and update it if so) and then check it against 0.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/cpuidle/governors/teo.c |   15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

--- a/drivers/cpuidle/governors/teo.c
+++ b/drivers/cpuidle/governors/teo.c
@@ -428,6 +428,14 @@
 				break;
 		}
 	}
+
+	/*
+	 * If there is a latency constraint, it may be necessary to select an
+	 * idle state shallower than the current candidate one.
+	 */
+	if (idx > constraint_idx)
+		idx = constraint_idx;
+
 	if (!idx && prev_intercept_idx &&
 	    !(drv->states[0].flags & CPUIDLE_FLAG_POLLING)) {
 		/*
@@ -440,13 +448,6 @@
 	}

 	/*
-	 * If there is a latency constraint, it may be necessary to select an
-	 * idle state shallower than the current candidate one.
-	 */
-	if (idx > constraint_idx)
-		idx = constraint_idx;
-
-	/*
 	 * Skip the timers check if state 0 is the current candidate one,
 	 * because an immediate non-timer wakeup is expected in that case.
 	 */