Commit 1ebe8f7e authored by Christian Loehle's avatar Christian Loehle Committed by Rafael J. Wysocki
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PM: EM: Fix late boot with holes in CPU topology 



Commit e3f1164f ("PM: EM: Support late CPUs booting and capacity
adjustment") added a mechanism to handle CPUs that come up late by
retrying when any of the `cpufreq_cpu_get()` call fails.

However, if there are holes in the CPU topology (offline CPUs, e.g.
nosmt), the first missing CPU causes the loop to break, preventing
subsequent online CPUs from being updated.

Instead of aborting on the first missing CPU policy, loop through all
and retry if any were missing.

Fixes: e3f1164f ("PM: EM: Support late CPUs booting and capacity adjustment")
Suggested-by: default avatarKenneth Crudup <kenneth.crudup@gmail.com>
Reported-by: default avatarKenneth Crudup <kenneth.crudup@gmail.com>
Link: https://lore.kernel.org/linux-pm/40212796-734c-4140-8a85-854f72b8144d@panix.com/


Cc: 6.9+ <stable@vger.kernel.org> # 6.9+
Signed-off-by: default avatarChristian Loehle <christian.loehle@arm.com>
Link: https://patch.msgid.link/20250831214357.2020076-1-christian.loehle@arm.com


[ rjw: Drop the new pr_debug() message which is not very useful ]
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent e0423541

kernel/power/energy_model.c

+6 −5
Original line number Diff line number Diff line
@@ -799,7 +799,7 @@ void em_adjust_cpu_capacity(unsigned int cpu) 
static void em_check_capacity_update(void)

{

	cpumask_var_t cpu_done_mask;

	int cpu;

	int cpu, failed_cpus = 0;



	if (!zalloc_cpumask_var(&cpu_done_mask, GFP_KERNEL)) {

		pr_warn("no free memory\n");
@@ -817,10 +817,8 @@ static void em_check_capacity_update(void) 


		policy = cpufreq_cpu_get(cpu);

		if (!policy) {

			pr_debug("Accessing cpu%d policy failed\n", cpu);

			schedule_delayed_work(&em_update_work,

					      msecs_to_jiffies(1000));

			break;

			failed_cpus++;

			continue;

		}

		cpufreq_cpu_put(policy);
@@ -835,6 +833,9 @@ static void em_check_capacity_update(void) 
		em_adjust_new_capacity(cpu, dev, pd);

	}



	if (failed_cpus)

		schedule_delayed_work(&em_update_work, msecs_to_jiffies(1000));



	free_cpumask_var(cpu_done_mask);

}