Revert "clk: Use hashtable for global clk lookups"

This reverts commit 4bf2d27.

Author: popcornmix

drivers/clk/clk.c

@@ -12,7 +12,6 @@
 #include <linux/clk-provider.h>
 #include <linux/device.h>
 #include <linux/err.h>
-#include <linux/hashtable.h>
 #include <linux/init.h>
 #include <linux/list.h>
 #include <linux/module.h>
@@ -22,8 +21,6 @@
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
-#include <linux/string.h>
-#include <linux/stringhash.h>
 
 #include "clk.h"
 
@@ -36,9 +33,6 @@ static struct task_struct *enable_owner;
 static int prepare_refcnt;
 static int enable_refcnt;
 
-#define CLK_HASH_BITS 9
-static DEFINE_HASHTABLE(clk_hashtable, CLK_HASH_BITS);
-
 static HLIST_HEAD(clk_root_list);
 static HLIST_HEAD(clk_orphan_list);
 static LIST_HEAD(clk_notifier_list);
@@ -93,7 +87,6 @@ struct clk_core {
 	struct clk_duty		duty;
 	struct hlist_head	children;
 	struct hlist_node	child_node;
-	struct hlist_node	hashtable_node;
 	struct hlist_head	clks;
 	unsigned int		notifier_count;
 #ifdef CONFIG_DEBUG_FS
@@ -402,20 +395,45 @@ struct clk_hw *clk_hw_get_parent(const struct clk_hw *hw)
 }
 EXPORT_SYMBOL_GPL(clk_hw_get_parent);
 
+static struct clk_core *__clk_lookup_subtree(const char *name,
+					     struct clk_core *core)
+{
+	struct clk_core *child;
+	struct clk_core *ret;
+
+	if (!strcmp(core->name, name))
+		return core;
+
+	hlist_for_each_entry(child, &core->children, child_node) {
+		ret = __clk_lookup_subtree(name, child);
+		if (ret)
+			return ret;
+	}
+
+	return NULL;
+}
+
 static struct clk_core *clk_core_lookup(const char *name)
 {
-	struct clk_core *core;
-	u32 hash;
+	struct clk_core *root_clk;
+	struct clk_core *ret;
 
 	if (!name)
 		return NULL;
 
-	hash = full_name_hash(NULL, name, strlen(name));
+	/* search the 'proper' clk tree first */
+	hlist_for_each_entry(root_clk, &clk_root_list, child_node) {
+		ret = __clk_lookup_subtree(name, root_clk);
+		if (ret)
+			return ret;
+	}
 
-	/* search the hashtable */
-	hash_for_each_possible(clk_hashtable, core, hashtable_node, hash)
-		if (!strcmp(core->name, name))
-			return core;
+	/* if not found, then search the orphan tree */
+	hlist_for_each_entry(root_clk, &clk_orphan_list, child_node) {
+		ret = __clk_lookup_subtree(name, root_clk);
+		if (ret)
+			return ret;
+	}
 
 	return NULL;
 }
@@ -3995,8 +4013,6 @@ static int __clk_core_init(struct clk_core *core)
 		hlist_add_head(&core->child_node, &clk_orphan_list);
 		core->orphan = true;
 	}
-	hash_add(clk_hashtable, &core->hashtable_node,
-		 full_name_hash(NULL, core->name, strlen(core->name)));
 
 	/*
 	 * Set clk's accuracy.  The preferred method is to use
@@ -4073,7 +4089,6 @@ static int __clk_core_init(struct clk_core *core)
 	clk_pm_runtime_put(core);
 unlock:
 	if (ret) {
-		hash_del(&core->hashtable_node);
 		hlist_del_init(&core->child_node);
 		core->hw->core = NULL;
 	}
@@ -4595,7 +4610,6 @@ void clk_unregister(struct clk *clk)
 
 	clk_core_evict_parent_cache(clk->core);
 
-	hash_del(&clk->core->hashtable_node);
 	hlist_del_init(&clk->core->child_node);
 
 	if (clk->core->prepare_count)