These were needed by TMEM only, which is long gone. The Linux original
doesn't have such either. This effectively reverts one of the "Other
changes" from 8dc6738dbb3c ("Update radix-tree.[ch] from upstream Linux
to gain RCU awareness").

Positive side effect: Two cf_check go away.

While there also convert xmalloc()+memset() to xzalloc(). (Don't convert
to xvzalloc(), as that would require touching the freeing side, too.)

Requested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v2: New.

--- a/xen/common/radix-tree.c
+++ b/xen/common/radix-tree.c
@@ -53,12 +53,6 @@ struct rcu_node {
 	struct rcu_head rcu_head;
 };
 
-static struct radix_tree_node *cf_check rcu_node_alloc(void *arg)
-{
-	struct rcu_node *rcu_node = xmalloc(struct rcu_node);
-	return rcu_node ? &rcu_node->node : NULL;
-}
-
 static void cf_check _rcu_node_free(struct rcu_head *head)
 {
 	struct rcu_node *rcu_node =
@@ -66,26 +60,19 @@ static void cf_check _rcu_node_free(stru
 	xfree(rcu_node);
 }
 
-static void cf_check rcu_node_free(struct radix_tree_node *node, void *arg)
-{
-	struct rcu_node *rcu_node = container_of(node, struct rcu_node, node);
-	call_rcu(&rcu_node->rcu_head, _rcu_node_free);
-}
-
 static struct radix_tree_node *radix_tree_node_alloc(
 	struct radix_tree_root *root)
 {
-	struct radix_tree_node *ret;
-	ret = root->node_alloc(root->node_alloc_free_arg);
-	if (ret)
-		memset(ret, 0, sizeof(*ret));
-	return ret;
+	struct rcu_node *rcu_node = xzalloc(struct rcu_node);
+
+	return rcu_node ? &rcu_node->node : NULL;
 }
 
 static void radix_tree_node_free(
 	struct radix_tree_root *root, struct radix_tree_node *node)
 {
-	root->node_free(node, root->node_alloc_free_arg);
+	struct rcu_node *rcu_node = container_of(node, struct rcu_node, node);
+	call_rcu(&rcu_node->rcu_head, _rcu_node_free);
 }
 
 /*
@@ -718,19 +705,6 @@ void radix_tree_destroy(
 void radix_tree_init(struct radix_tree_root *root)
 {
 	memset(root, 0, sizeof(*root));
-	root->node_alloc = rcu_node_alloc;
-	root->node_free = rcu_node_free;
-}
-
-void radix_tree_set_alloc_callbacks(
-	struct radix_tree_root *root,
-	radix_tree_alloc_fn_t *node_alloc,
-	radix_tree_free_fn_t *node_free,
-	void *node_alloc_free_arg)
-{
-	root->node_alloc = node_alloc;
-	root->node_free = node_free;
-	root->node_alloc_free_arg = node_alloc_free_arg;
 }
 
 static __init unsigned long __maxindex(unsigned int height)
--- a/xen/include/xen/radix-tree.h
+++ b/xen/include/xen/radix-tree.h
@@ -66,11 +66,6 @@ typedef void radix_tree_free_fn_t(struct
 struct radix_tree_root {
 	unsigned int		height;
 	struct radix_tree_node	__rcu *rnode;
-
-	/* Allow to specify custom node alloc/dealloc routines. */
-	radix_tree_alloc_fn_t *node_alloc;
-	radix_tree_free_fn_t *node_free;
-	void *node_alloc_free_arg;
 };
 
 /*
@@ -78,11 +73,6 @@ struct radix_tree_root {
  */
 
 void radix_tree_init(struct radix_tree_root *root);
-void radix_tree_set_alloc_callbacks(
-	struct radix_tree_root *root,
-	radix_tree_alloc_fn_t *node_alloc,
-	radix_tree_free_fn_t *node_free,
-	void *node_alloc_free_arg);
 
 void radix_tree_destroy(
 	struct radix_tree_root *root,

On 03/02/2025 4:25 pm, Jan Beulich wrote:
> These were needed by TMEM only, which is long gone. The Linux original
> doesn't have such either. This effectively reverts one of the "Other
> changes" from 8dc6738dbb3c ("Update radix-tree.[ch] from upstream Linux
> to gain RCU awareness").
>
> Positive side effect: Two cf_check go away.

Not only that, they can now be inlined, although you've merged them
directly.

>
> While there also convert xmalloc()+memset() to xzalloc(). (Don't convert
> to xvzalloc(), as that would require touching the freeing side, too.)
>
> Requested-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

One formatting point.

> --- a/xen/common/radix-tree.c
> +++ b/xen/common/radix-tree.c
> @@ -66,26 +60,19 @@ static void cf_check _rcu_node_free(stru
>  	xfree(rcu_node);
>  }
>  
> -static void cf_check rcu_node_free(struct radix_tree_node *node, void *arg)
> -{
> -	struct rcu_node *rcu_node = container_of(node, struct rcu_node, node);
> -	call_rcu(&rcu_node->rcu_head, _rcu_node_free);
> -}
> -
>  static struct radix_tree_node *radix_tree_node_alloc(
>  	struct radix_tree_root *root)
>  {
> -	struct radix_tree_node *ret;
> -	ret = root->node_alloc(root->node_alloc_free_arg);
> -	if (ret)
> -		memset(ret, 0, sizeof(*ret));
> -	return ret;
> +	struct rcu_node *rcu_node = xzalloc(struct rcu_node);
> +
> +	return rcu_node ? &rcu_node->node : NULL;
>  }
>  
>  static void radix_tree_node_free(
>  	struct radix_tree_root *root, struct radix_tree_node *node)
>  {
> -	root->node_free(node, root->node_alloc_free_arg);
> +	struct rcu_node *rcu_node = container_of(node, struct rcu_node, node);

Newline here.

~Andrew

> +	call_rcu(&rcu_node->rcu_head, _rcu_node_free);
>  }
>  
>  /*
>

On 03.02.2025 17:25, Jan Beulich wrote:
> These were needed by TMEM only, which is long gone. The Linux original
> doesn't have such either. This effectively reverts one of the "Other
> changes" from 8dc6738dbb3c ("Update radix-tree.[ch] from upstream Linux
> to gain RCU awareness").
> 
> Positive side effect: Two cf_check go away.
> 
> While there also convert xmalloc()+memset() to xzalloc(). (Don't convert
> to xvzalloc(), as that would require touching the freeing side, too.)
> 
> Requested-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

I'm sorry, the question mark after for-4.20 was somehow lost in the
submission.

Jan