PM: EM: Address RCU-related sparse warnings

The usage of __rcu in the Energy Model code is quite inconsistent
which causes the following sparse warnings to trigger:

kernel/power/energy_model.c:169:15: warning: incorrect type in assignment (different address spaces)
kernel/power/energy_model.c:169:15:    expected struct em_perf_table [noderef] __rcu *table
kernel/power/energy_model.c:169:15:    got struct em_perf_table *
kernel/power/energy_model.c:171:9: warning: incorrect type in argument 1 (different address spaces)
kernel/power/energy_model.c:171:9:    expected struct callback_head *head
kernel/power/energy_model.c:171:9:    got struct callback_head [noderef] __rcu *
kernel/power/energy_model.c:171:9: warning: cast removes address space '__rcu' of expression
kernel/power/energy_model.c:182:19: warning: incorrect type in argument 1 (different address spaces)
kernel/power/energy_model.c:182:19:    expected struct kref *kref
kernel/power/energy_model.c:182:19:    got struct kref [noderef] __rcu *
kernel/power/energy_model.c:200:15: warning: incorrect type in assignment (different address spaces)
kernel/power/energy_model.c:200:15:    expected struct em_perf_table [noderef] __rcu *table
kernel/power/energy_model.c:200:15:    got void *[assigned] _res
kernel/power/energy_model.c:204:20: warning: incorrect type in argument 1 (different address spaces)
kernel/power/energy_model.c:204:20:    expected struct kref *kref
kernel/power/energy_model.c:204:20:    got struct kref [noderef] __rcu *
kernel/power/energy_model.c:320:19: warning: incorrect type in argument 1 (different address spaces)
kernel/power/energy_model.c:320:19:    expected struct kref *kref
kernel/power/energy_model.c:320:19:    got struct kref [noderef] __rcu *
kernel/power/energy_model.c:325:45: warning: incorrect type in argument 2 (different address spaces)
kernel/power/energy_model.c:325:45:    expected struct em_perf_state *table
kernel/power/energy_model.c:325:45:    got struct em_perf_state [noderef] __rcu *
kernel/power/energy_model.c:425:45: warning: incorrect type in argument 3 (different address spaces)
kernel/power/energy_model.c:425:45:    expected struct em_perf_state *table
kernel/power/energy_model.c:425:45:    got struct em_perf_state [noderef] __rcu *
kernel/power/energy_model.c:442:15: warning: incorrect type in argument 1 (different address spaces)
kernel/power/energy_model.c:442:15:    expected void const *objp
kernel/power/energy_model.c:442:15:    got struct em_perf_table [noderef] __rcu *[assigned] em_table
kernel/power/energy_model.c:626:55: warning: incorrect type in argument 2 (different address spaces)
kernel/power/energy_model.c:626:55:    expected struct em_perf_state *table
kernel/power/energy_model.c:626:55:    got struct em_perf_state [noderef] __rcu *
kernel/power/energy_model.c:681:16: warning: incorrect type in assignment (different address spaces)
kernel/power/energy_model.c:681:16:    expected struct em_perf_state *new_ps
kernel/power/energy_model.c:681:16:    got struct em_perf_state [noderef] __rcu *
kernel/power/energy_model.c:699:37: warning: incorrect type in argument 2 (different address spaces)
kernel/power/energy_model.c:699:37:    expected struct em_perf_state *table
kernel/power/energy_model.c:699:37:    got struct em_perf_state [noderef] __rcu *
kernel/power/energy_model.c:733:38: warning: incorrect type in argument 3 (different address spaces)
kernel/power/energy_model.c:733:38:    expected struct em_perf_state *table
kernel/power/energy_model.c:733:38:    got struct em_perf_state [noderef] __rcu *
kernel/power/energy_model.c:855:53: warning: dereference of noderef expression
kernel/power/energy_model.c:864:32: warning: dereference of noderef expression

This is because the __rcu annotation for sparse is only applicable to
pointers that need rcu_dereference() or equivalent for protection, which
basically means pointers assigned with rcu_assign_pointer().

Make all of the above sparse warnings go away by cleaning up the usage
of __rcu and using rcu_dereference_protected() where applicable.

Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Link: https://patch.msgid.link/5885405.DvuYhMxLoT@rjwysocki.net

1 files changed, 6 insertions, 6 deletions

diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
index b23c8c798dac..ddd09debfc7d 100644
--- a/include/linux/energy_model.h
+++ b/include/linux/energy_model.h
@@ -167,13 +167,13 @@ struct em_data_callback {
 struct em_perf_domain *em_cpu_get(int cpu);
 struct em_perf_domain *em_pd_get(struct device *dev);
 int em_dev_update_perf_domain(struct device *dev,
-			      struct em_perf_table __rcu *new_table);
+			      struct em_perf_table *new_table);
 int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
 				const struct em_data_callback *cb,
 				const cpumask_t *cpus, bool microwatts);
 void em_dev_unregister_perf_domain(struct device *dev);
-struct em_perf_table __rcu *em_table_alloc(struct em_perf_domain *pd);
-void em_table_free(struct em_perf_table __rcu *table);
+struct em_perf_table *em_table_alloc(struct em_perf_domain *pd);
+void em_table_free(struct em_perf_table *table);
 int em_dev_compute_costs(struct device *dev, struct em_perf_state *table,
 			 int nr_states);
 int em_dev_update_chip_binning(struct device *dev);
@@ -373,14 +373,14 @@ static inline int em_pd_nr_perf_states(struct em_perf_domain *pd)
 	return 0;
 }
 static inline
-struct em_perf_table __rcu *em_table_alloc(struct em_perf_domain *pd)
+struct em_perf_table *em_table_alloc(struct em_perf_domain *pd)
 {
 	return NULL;
 }
-static inline void em_table_free(struct em_perf_table __rcu *table) {}
+static inline void em_table_free(struct em_perf_table *table) {}
 static inline
 int em_dev_update_perf_domain(struct device *dev,
-			      struct em_perf_table __rcu *new_table)
+			      struct em_perf_table *new_table)
 {
 	return -EINVAL;
 }