linux-kernel - [PATCH 1/2] cpufreq: Fix re-boost issue after hotplugging a cpu

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250115100123.241110-2-zhenglifeng1@huawei.com>
Date: Wed, 15 Jan 2025 18:01:22 +0800
From: Lifeng Zheng <zhenglifeng1@...wei.com>
To: <rafael@...nel.org>, <viresh.kumar@...aro.org>
CC: <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linuxarm@...wei.com>, <jonathan.cameron@...wei.com>,
	<zhanjie9@...ilicon.com>, <lihuisong@...wei.com>, <zhenglifeng1@...wei.com>,
	<fanghao11@...wei.com>
Subject: [PATCH 1/2] cpufreq: Fix re-boost issue after hotplugging a cpu

It turns out that cpuX will stay on the base frequency after performing
these operations:

1. boost all cpus: echo 1 > /sys/devices/system/cpu/cpufreq/boost

2. offline the cpu: echo 0 > /sys/devices/system/cpu/cpuX/online

3. deboost all cpus: echo 0 > /sys/devices/system/cpu/cpufreq/boost

4. online the cpu: echo 1 > /sys/devices/system/cpu/cpuX/online

5. boost all cpus again: echo 1 > /sys/devices/system/cpu/cpufreq/boost

This is because max_freq_req of the policy is not updated during the
online process, and the value of max_freq_req before the last offline is
retained. When the CPU is boosted again, freq_qos_update_request() will
do nothing because the old value is the same as the new one. This causes
the CPU stay on the base frequency. Update max_freq_req (and
min_freq_req of course) in cpufreq_online() will solve this problem.

Signed-off-by: Lifeng Zheng <zhenglifeng1@...wei.com>
---
 drivers/cpufreq/cpufreq.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 1a4cae54a01b..03ae879d50b9 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1475,6 +1475,13 @@ static int cpufreq_online(unsigned int cpu)
 
 		blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
 				CPUFREQ_CREATE_POLICY, policy);
+	} else {
+		ret = freq_qos_update_request(policy->min_freq_req, policy->min);
+		if (ret < 0)
+			goto out_destroy_policy;
+		ret = freq_qos_update_request(policy->max_freq_req, policy->max);
+		if (ret < 0)
+			goto out_destroy_policy;
 	}
 
 	if (cpufreq_driver->get && has_target()) {
-- 
2.33.0