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From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Linux PM <linux-pm@vger.kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Lukasz Luba <lukasz.luba@arm.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
	Christian Loehle <christian.loehle@arm.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>
Subject: [PATCH v1] cpufreq: Drop policy locking from cpufreq_policy_is_good_for_eas()
Date: Mon, 12 May 2025 15:23:30 +0200	[thread overview]
Message-ID: <2806514.mvXUDI8C0e@rjwysocki.net> (raw)
In-Reply-To: <3344336.aeNJFYEL58@rjwysocki.net>

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

Policy locking was added to cpufreq_policy_is_good_for_eas() by commit
4854649b1fb4 ("cpufreq/sched: Move cpufreq-specific EAS checks to
cpufreq") to address a theoretical race condition, but it turned out to
introduce a circular locking dependency between the policy rwsem and
sched_domains_mutex via cpuset_mutex. This leads to a board lockup on
OdroidN2 that is based on the ARM64 Amlogic Meson SoC.

Drop the policy locking from cpufreq_policy_is_good_for_eas() to address
this issue.

Fixes: 4854649b1fb4 ("cpufreq/sched: Move cpufreq-specific EAS checks to cpufreq")
Closes: https://lore.kernel.org/linux-pm/1bf3df62-0641-459f-99fc-fd511e564b84@samsung.com/
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/cpufreq/cpufreq.c |    2 --
 1 file changed, 2 deletions(-)

--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -3067,8 +3067,6 @@
 		return false;
 	}
 
-	guard(cpufreq_policy_read)(policy);
-
 	return sugov_is_governor(policy);
 }
 




      parent reply	other threads:[~2025-05-12 13:23 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-16 17:44 [RFT][PATCH v1 0/8] cpufreq: intel_pstate: Enable EAS on hybrid platforms without SMT Rafael J. Wysocki
2025-04-16 17:48 ` [RFT][PATCH v1 1/8] cpufreq/sched: schedutil: Add helper for governor checks Rafael J. Wysocki
2025-04-17 12:23   ` Christian Loehle
2025-04-16 17:59 ` [RFT][PATCH v1 2/8] cpufreq/sched: Move cpufreq-specific EAS checks to cpufreq Rafael J. Wysocki
2025-04-17 12:28   ` Christian Loehle
2025-04-16 18:01 ` [RFT][PATCH v1 3/8] cpufreq/sched: Allow .setpolicy() cpufreq drivers to enable EAS Rafael J. Wysocki
2025-04-17 12:19   ` Christian Loehle
2025-04-17 13:01     ` Rafael J. Wysocki
2025-04-17 13:03       ` Christian Loehle
2025-04-16 18:04 ` [RFT][PATCH v1 4/8] PM: EM: Move CPU capacity check to em_adjust_new_capacity() Rafael J. Wysocki
2025-04-16 18:06 ` [RFT][PATCH v1 5/8] PM: EM: Introduce em_adjust_cpu_capacity() Rafael J. Wysocki
2025-04-27 14:01   ` Dietmar Eggemann
2025-04-30 19:23     ` Rafael J. Wysocki
2025-05-01 12:30       ` Dietmar Eggemann
2025-05-06 19:46         ` Rafael J. Wysocki
2025-04-16 18:09 ` [RFT][PATCH v1 6/8] cpufreq: intel_pstate: EAS support for hybrid platforms Rafael J. Wysocki
2025-04-16 18:10 ` [RFT][PATCH v1 7/8] cpufreq: intel_pstate: Align perf domains with L2 cache Rafael J. Wysocki
2025-04-17 12:42   ` Christian Loehle
2025-04-27 16:23   ` Dietmar Eggemann
2025-04-30 19:29     ` Rafael J. Wysocki
2025-05-01 12:30       ` Dietmar Eggemann
2025-04-16 18:12 ` [RFT][PATCH v1 8/8] cpufreq: intel_pstate: EAS: Increase cost for CPUs using L3 cache Rafael J. Wysocki
2025-04-25 21:32   ` Christian Loehle
2025-04-25 21:39     ` Rafael J. Wysocki
2025-04-18  9:58 ` [RFT][PATCH v1 0/8] cpufreq: intel_pstate: Enable EAS on hybrid platforms without SMT Christian Loehle
2025-04-18 19:52   ` Rafael J. Wysocki
2025-05-12 13:23 ` Rafael J. Wysocki [this message]

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