linux-kernel - [PATCH v1] cpufreq: intel_pstate: Rearrange locking in hybrid_init_cpu_capacity

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Message-ID: <12554508.O9o76ZdvQC@rjwysocki.net>
Date: Thu, 07 Nov 2024 13:36:10 +0100
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
 Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
 Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
Subject:
 [PATCH v1] cpufreq: intel_pstate: Rearrange locking in
 hybrid_init_cpu_capacity_scaling()

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

Notice that hybrid_init_cpu_capacity_scaling() only needs to hold
hybrid_capacity_lock around __hybrid_init_cpu_capacity_scaling()
calls, so introduce a "locked" wrapper around the latter and call
it from the former.  This allows to drop a local variable and a
label that are not needed any more.

Also, rename __hybrid_init_cpu_capacity_scaling() to
__hybrid_refresh_cpu_capacity_scaling() for consistency.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---

This is on top of

https://lore.kernel.org/linux-pm/12555220.O9o76ZdvQC@rjwysocki.net/

---
 drivers/cpufreq/intel_pstate.c |   35 ++++++++++++++++-------------------
 1 file changed, 16 insertions(+), 19 deletions(-)

Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/intel_pstate.c
+++ linux-pm/drivers/cpufreq/intel_pstate.c
@@ -1028,26 +1028,29 @@ static void hybrid_update_cpu_capacity_s
 	}
 }
 
-static void __hybrid_init_cpu_capacity_scaling(void)
+static void __hybrid_refresh_cpu_capacity_scaling(void)
 {
 	hybrid_max_perf_cpu = NULL;
 	hybrid_update_cpu_capacity_scaling();
 }
 
-static void hybrid_init_cpu_capacity_scaling(bool refresh)
+static void hybrid_refresh_cpu_capacity_scaling(void)
 {
-	bool disable_itmt = false;
+	guard(mutex)(&hybrid_capacity_lock);
 
-	mutex_lock(&hybrid_capacity_lock);
+	__hybrid_refresh_cpu_capacity_scaling();
+}
 
+static void hybrid_init_cpu_capacity_scaling(bool refresh)
+{
 	/*
 	 * If hybrid_max_perf_cpu is set at this point, the hybrid CPU capacity
 	 * scaling has been enabled already and the driver is just changing the
 	 * operation mode.
 	 */
 	if (refresh) {
-		__hybrid_init_cpu_capacity_scaling();
-		goto unlock;
+		hybrid_refresh_cpu_capacity_scaling();
+		return;
 	}
 
 	/*
@@ -1056,19 +1059,13 @@ static void hybrid_init_cpu_capacity_sca
 	 * do not do that when SMT is in use.
 	 */
 	if (hwp_is_hybrid && !sched_smt_active() && arch_enable_hybrid_capacity_scale()) {
-		__hybrid_init_cpu_capacity_scaling();
-		disable_itmt = true;
-	}
-
-unlock:
-	mutex_unlock(&hybrid_capacity_lock);
-
-	/*
-	 * Disabling ITMT causes sched domains to be rebuilt to disable asym
-	 * packing and enable asym capacity.
-	 */
-	if (disable_itmt)
+		hybrid_refresh_cpu_capacity_scaling();
+		/*
+		 * Disabling ITMT causes sched domains to be rebuilt to disable asym
+		 * packing and enable asym capacity.
+		 */
 		sched_clear_itmt_support();
+	}
 }
 
 static bool hybrid_clear_max_perf_cpu(void)
@@ -1404,7 +1401,7 @@ static void intel_pstate_update_limits_f
 	mutex_lock(&hybrid_capacity_lock);
 
 	if (hybrid_max_perf_cpu)
-		__hybrid_init_cpu_capacity_scaling();
+		__hybrid_refresh_cpu_capacity_scaling();
 
 	mutex_unlock(&hybrid_capacity_lock);
 }