6.12-stable review patch. If anyone has any objections, please let me know.
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From: Rafael J. Wysocki rafael.j.wysocki@intel.com
[ Upstream commit 3ee7be9e10dd5f79448788b899591d4bd2bf0c19 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/energy_model.h | 12 +++++------ kernel/power/energy_model.c | 39 ++++++++++++++++++------------------ 2 files changed, 26 insertions(+), 25 deletions(-)
diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h index 1ff52020cf757..34498652f7802 100644 --- a/include/linux/energy_model.h +++ b/include/linux/energy_model.h @@ -163,13 +163,13 @@ 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, struct em_data_callback *cb, cpumask_t *span, 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); @@ -365,14 +365,14 @@ 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; } diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c index e303d938637f1..4e1778071d704 100644 --- a/kernel/power/energy_model.c +++ b/kernel/power/energy_model.c @@ -163,12 +163,8 @@ static void em_debug_remove_pd(struct device *dev) {}
static void em_release_table_kref(struct kref *kref) { - struct em_perf_table __rcu *table; - /* It was the last owner of this table so we can free */ - table = container_of(kref, struct em_perf_table, kref); - - kfree_rcu(table, rcu); + kfree_rcu(container_of(kref, struct em_perf_table, kref), rcu); }
/** @@ -177,7 +173,7 @@ static void em_release_table_kref(struct kref *kref) * * No return values. */ -void em_table_free(struct em_perf_table __rcu *table) +void em_table_free(struct em_perf_table *table) { kref_put(&table->kref, em_release_table_kref); } @@ -190,9 +186,9 @@ void em_table_free(struct em_perf_table __rcu *table) * has a user. * Returns allocated table or NULL. */ -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) { - struct em_perf_table __rcu *table; + struct em_perf_table *table; int table_size;
table_size = sizeof(struct em_perf_state) * pd->nr_perf_states; @@ -300,9 +296,9 @@ int em_dev_compute_costs(struct device *dev, struct em_perf_state *table, * Return 0 on success or an error code on failure. */ int em_dev_update_perf_domain(struct device *dev, - struct em_perf_table __rcu *new_table) + struct em_perf_table *new_table) { - struct em_perf_table __rcu *old_table; + struct em_perf_table *old_table; struct em_perf_domain *pd;
if (!dev) @@ -319,7 +315,8 @@ int em_dev_update_perf_domain(struct device *dev,
kref_get(&new_table->kref);
- old_table = pd->em_table; + old_table = rcu_dereference_protected(pd->em_table, + lockdep_is_held(&em_pd_mutex)); rcu_assign_pointer(pd->em_table, new_table);
em_cpufreq_update_efficiencies(dev, new_table->state); @@ -391,7 +388,7 @@ static int em_create_pd(struct device *dev, int nr_states, struct em_data_callback *cb, cpumask_t *cpus, unsigned long flags) { - struct em_perf_table __rcu *em_table; + struct em_perf_table *em_table; struct em_perf_domain *pd; struct device *cpu_dev; int cpu, ret, num_cpus; @@ -551,6 +548,7 @@ int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states, struct em_data_callback *cb, cpumask_t *cpus, bool microwatts) { + struct em_perf_table *em_table; unsigned long cap, prev_cap = 0; unsigned long flags = 0; int cpu, ret; @@ -621,7 +619,9 @@ int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
dev->em_pd->flags |= flags;
- em_cpufreq_update_efficiencies(dev, dev->em_pd->em_table->state); + em_table = rcu_dereference_protected(dev->em_pd->em_table, + lockdep_is_held(&em_pd_mutex)); + em_cpufreq_update_efficiencies(dev, em_table->state);
em_debug_create_pd(dev); dev_info(dev, "EM: created perf domain\n"); @@ -658,7 +658,8 @@ void em_dev_unregister_perf_domain(struct device *dev) mutex_lock(&em_pd_mutex); em_debug_remove_pd(dev);
- em_table_free(dev->em_pd->em_table); + em_table_free(rcu_dereference_protected(dev->em_pd->em_table, + lockdep_is_held(&em_pd_mutex)));
kfree(dev->em_pd); dev->em_pd = NULL; @@ -666,9 +667,9 @@ void em_dev_unregister_perf_domain(struct device *dev) } EXPORT_SYMBOL_GPL(em_dev_unregister_perf_domain);
-static struct em_perf_table __rcu *em_table_dup(struct em_perf_domain *pd) +static struct em_perf_table *em_table_dup(struct em_perf_domain *pd) { - struct em_perf_table __rcu *em_table; + struct em_perf_table *em_table; struct em_perf_state *ps, *new_ps; int ps_size;
@@ -690,7 +691,7 @@ static struct em_perf_table __rcu *em_table_dup(struct em_perf_domain *pd) }
static int em_recalc_and_update(struct device *dev, struct em_perf_domain *pd, - struct em_perf_table __rcu *em_table) + struct em_perf_table *em_table) { int ret;
@@ -721,7 +722,7 @@ static void em_adjust_new_capacity(struct device *dev, struct em_perf_domain *pd, u64 max_cap) { - struct em_perf_table __rcu *em_table; + struct em_perf_table *em_table;
em_table = em_table_dup(pd); if (!em_table) { @@ -812,7 +813,7 @@ static void em_update_workfn(struct work_struct *work) */ int em_dev_update_chip_binning(struct device *dev) { - struct em_perf_table __rcu *em_table; + struct em_perf_table *em_table; struct em_perf_domain *pd; int i, ret;