PM: EM: Fix late boot with holes in CPU topology

[ Upstream commit 1ebe8f7e782523e62cd1fa8237f7afba5d1dae83 ]

Commit e3f1164fc9ee ("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: e3f1164fc9ee ("PM: EM: Support late CPUs booting and capacity adjustment")
Suggested-by: Kenneth Crudup <kenneth.crudup@gmail.com>
Reported-by: Kenneth 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: Christian 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: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
index 2ef0a7d9d8405a67e0ccebdb967fc357d47f55d8..d839b564522f668ba9f31101da24f4b75636691f 100644 (file)
--- a/kernel/power/energy_model.c
+++ b/kernel/power/energy_model.c
@@ -755,7 +755,7 @@ static void em_adjust_new_capacity(unsigned int cpu, struct device *dev,
 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");
@@ -773,10 +773,8 @@ 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);
 
@@ -791,6 +789,9 @@ 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);
 }