From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Date: Mon, 25 Mar 2024 17:04:24 +0000 (+0100)
Subject: cpufreq: intel_pstate: Read global.no_turbo under READ_ONCE()
X-Git-Tag: v6.6.105~4
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d0b26a9f5742148480822babcc357439071f11e9;p=thirdparty%2Fkernel%2Fstable.git

cpufreq: intel_pstate: Read global.no_turbo under READ_ONCE()

[ Upstream commit 9558fae8ce97b3b320b387dd7c88309df2c36d4d ]

Because global.no_turbo is generally not read under intel_pstate_driver_lock
make store_no_turbo() use WRITE_ONCE() for updating it (this is the only
place at which it is updated except for the initialization) and make the
majority of places reading it use READ_ONCE().

Also remove redundant global.turbo_disabled checks from places that
depend on the 'true' value of global.no_turbo because it can only be
'true' if global.turbo_disabled is also 'true'.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Stable-dep-of: 350cbb5d2f67 ("cpufreq: intel_pstate: Check turbo_is_disabled() in store_no_turbo()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 8bac7afb13a3d..05aae7e6da157 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -1297,7 +1297,7 @@ static ssize_t store_no_turbo(struct kobject *a, struct kobj_attribute *b,
 		goto unlock_driver;
 	}
 
-	global.no_turbo = no_turbo;
+	WRITE_ONCE(global.no_turbo, no_turbo);
 
 	mutex_lock(&intel_pstate_limits_lock);
 
@@ -1766,7 +1766,7 @@ static u64 atom_get_val(struct cpudata *cpudata, int pstate)
 	u32 vid;
 
 	val = (u64)pstate << 8;
-	if (global.no_turbo && !global.turbo_disabled)
+	if (READ_ONCE(global.no_turbo) && !global.turbo_disabled)
 		val |= (u64)1 << 32;
 
 	vid_fp = cpudata->vid.min + mul_fp(
@@ -1931,7 +1931,7 @@ static u64 core_get_val(struct cpudata *cpudata, int pstate)
 	u64 val;
 
 	val = (u64)pstate << 8;
-	if (global.no_turbo && !global.turbo_disabled)
+	if (READ_ONCE(global.no_turbo) && !global.turbo_disabled)
 		val |= (u64)1 << 32;
 
 	return val;
@@ -2229,7 +2229,7 @@ static inline int32_t get_target_pstate(struct cpudata *cpu)
 
 	sample->busy_scaled = busy_frac * 100;
 
-	target = global.no_turbo || global.turbo_disabled ?
+	target = READ_ONCE(global.no_turbo) ?
 			cpu->pstate.max_pstate : cpu->pstate.turbo_pstate;
 	target += target >> 2;
 	target = mul_fp(target, busy_frac);
@@ -2490,7 +2490,7 @@ static void intel_pstate_clear_update_util_hook(unsigned int cpu)
 
 static int intel_pstate_get_max_freq(struct cpudata *cpu)
 {
-	return global.turbo_disabled || global.no_turbo ?
+	return READ_ONCE(global.no_turbo) ?
 			cpu->pstate.max_freq : cpu->pstate.turbo_freq;
 }
 
@@ -2627,7 +2627,7 @@ static void intel_pstate_verify_cpu_policy(struct cpudata *cpu,
 
 	if (hwp_active) {
 		intel_pstate_get_hwp_cap(cpu);
-		max_freq = global.no_turbo || global.turbo_disabled ?
+		max_freq = READ_ONCE(global.no_turbo) ?
 				cpu->pstate.max_freq : cpu->pstate.turbo_freq;
 	} else {
 		max_freq = intel_pstate_get_max_freq(cpu);