[PATCH 1/7] cacheinfo: Export get_cpu_cacheinfo_id() for loadable modules

[Tony Luck]

From: Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>

Loadable drivers that track bitfix filter state need the cache ID to
distinguish shared cache instances. Without access to the cache ID, CPUs
sharing the same cache cannot be associated with the same tracking state.

The existing helper cannot be used by loadable modules because it depends
on a non-exported symbol, preventing the such drivers from building as
a module.

Export get_cpu_cacheinfo_id() so loadable modules can retrieve cache IDs
through a common cacheinfo interface.

Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
---
 include/linux/cacheinfo.h | 12 +-----------
 drivers/base/cacheinfo.c  | 17 +++++++++++++++++
 2 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
index fc879ac4cc4f..56fa646df0d1 100644
--- a/include/linux/cacheinfo.h
+++ b/include/linux/cacheinfo.h
@@ -82,6 +82,7 @@ struct cpu_cacheinfo {
 };
 
 struct cpu_cacheinfo *get_cpu_cacheinfo(unsigned int cpu);
+int get_cpu_cacheinfo_id(int cpu, int level);
 int early_cache_level(unsigned int cpu);
 int init_cache_level(unsigned int cpu);
 int init_of_cache_level(unsigned int cpu);
@@ -137,17 +138,6 @@ static inline struct cacheinfo *get_cpu_cacheinfo_level(int cpu, int level)
 	return NULL;
 }
 
-/*
- * Get the id of the cache associated with @cpu at level @level.
- * cpuhp lock must be held.
- */
-static inline int get_cpu_cacheinfo_id(int cpu, int level)
-{
-	struct cacheinfo *ci = get_cpu_cacheinfo_level(cpu, level);
-
-	return ci ? ci->id : -1;
-}
-
 #if defined(CONFIG_ARM64) || defined(CONFIG_ARM)
 #define use_arch_cache_info()	(true)
 #else
diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index 70701d3bc81c..28d193bf6064 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -38,6 +38,23 @@ struct cpu_cacheinfo *get_cpu_cacheinfo(unsigned int cpu)
 	return ci_cacheinfo(cpu);
 }
 
+/**
+ * get_cpu_cacheinfo_id - Return the cache ID for a CPU and cache level
+ * @cpu: CPU number
+ * @level: Cache level
+ *
+ * The caller must hold the cpuhp lock.
+ *
+ * Return: Cache ID on success, or -1 if no matching cache exists.
+ */
+int get_cpu_cacheinfo_id(int cpu, int level)
+{
+	struct cacheinfo *ci = get_cpu_cacheinfo_level(cpu, level);
+
+	return ci ? ci->id : -1;
+}
+EXPORT_SYMBOL_GPL(get_cpu_cacheinfo_id);
+
 static inline bool cache_leaves_are_shared(struct cacheinfo *this_leaf,
 					   struct cacheinfo *sib_leaf)
 {
-- 
2.55.0