linux-kernel - [PATCH v1] cpufreq: Add defensive checks during driver registration

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Message-Id: <20250908085738.31602-1-zhangzihuan@kylinos.cn>
Date: Mon,  8 Sep 2025 16:57:38 +0800
From: Zihuan Zhang <zhangzihuan@...inos.cn>
To: "Rafael J . wysocki" <rafael@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>
Cc: zhenglifeng <zhenglifeng1@...wei.com>,
	linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Zihuan Zhang <zhangzihuan@...inos.cn>
Subject: [PATCH v1] cpufreq: Add defensive checks during driver registration

Currently, cpufreq allows drivers to implement both has_target() and
has_target_index(), which can lead to ambiguous or incorrect behavior.

This patch adds defensive checks in the driver registration path to
prevent invalid implementations. For example, a driver is no longer
allowed to implement both has_target() and has_target_index() at the
same time. These checks help catch driver mistakes early and improve
overall robustness, without affecting existing valid drivers.

Signed-off-by: Zihuan Zhang <zhangzihuan@...inos.cn>
---
 drivers/cpufreq/cpufreq.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index a615c98d80ca..cead6d4fa1ad 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2922,6 +2922,7 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 		return -EPROBE_DEFER;
 
 	if (!driver_data || !driver_data->verify || !driver_data->init ||
+	     (driver_data->target_index && driver_data->target) ||
 	     (!!driver_data->setpolicy == (driver_data->target_index || driver_data->target)) ||
 	     (!driver_data->get_intermediate != !driver_data->target_intermediate) ||
 	     (!driver_data->online != !driver_data->offline) ||
-- 
2.25.1