Commit 8ffe28b4 authored by Christian Loehle's avatar Christian Loehle Committed by Rafael J. Wysocki
Browse files

cpufreq: Initialize cpufreq-based invariance before subsys 



commit 2a6c7273 ("cpufreq: Initialize cpufreq-based
frequency-invariance later") postponed the frequency invariance
initialization to avoid disabling it in the error case.
This isn't locking safe, instead move the initialization up before
the subsys interface is registered (which will rebuild the
sched_domains) and add the corresponding disable on the error path.

Observed lockdep without this patch:
[    0.989686] ======================================================
[    0.989688] WARNING: possible circular locking dependency detected
[    0.989690] 6.17.0-rc4-cix-build+ #31 Tainted: G S
[    0.989691] ------------------------------------------------------
[    0.989692] swapper/0/1 is trying to acquire lock:
[    0.989693] ffff800082ada7f8 (sched_energy_mutex){+.+.}-{4:4}, at: rebuild_sched_domains_energy+0x30/0x58
[    0.989705]
               but task is already holding lock:
[    0.989706] ffff000088c89bc8 (&policy->rwsem){+.+.}-{4:4}, at: cpufreq_online+0x7f8/0xbe0
[    0.989713]
               which lock already depends on the new lock.

Fixes: 2a6c7273 ("cpufreq: Initialize cpufreq-based frequency-invariance later")
Signed-off-by: default avatarChristian Loehle <christian.loehle@arm.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent f83ec76b

drivers/cpufreq/cpufreq.c

+11 −9
Original line number Diff line number Diff line
@@ -2953,6 +2953,15 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) 
			goto err_null_driver;

	}



	/*

	 * Mark support for the scheduler's frequency invariance engine for

	 * drivers that implement target(), target_index() or fast_switch().

	 */

	if (!cpufreq_driver->setpolicy) {

		static_branch_enable_cpuslocked(&cpufreq_freq_invariance);

		pr_debug("cpufreq: supports frequency invariance\n");

	}



	ret = subsys_interface_register(&cpufreq_interface);

	if (ret)

		goto err_boost_unreg;
@@ -2974,21 +2983,14 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) 
	hp_online = ret;

	ret = 0;



	/*

	 * Mark support for the scheduler's frequency invariance engine for

	 * drivers that implement target(), target_index() or fast_switch().

	 */

	if (!cpufreq_driver->setpolicy) {

		static_branch_enable_cpuslocked(&cpufreq_freq_invariance);

		pr_debug("supports frequency invariance");

	}



	pr_debug("driver %s up and running\n", driver_data->name);

	goto out;



err_if_unreg:

	subsys_interface_unregister(&cpufreq_interface);

err_boost_unreg:

	if (!cpufreq_driver->setpolicy)

		static_branch_disable_cpuslocked(&cpufreq_freq_invariance);

	remove_boost_sysfs_file();

err_null_driver:

	write_lock_irqsave(&cpufreq_driver_lock, flags);