Re: [PATCH bpf-next 07/10] bpf: Switch to bpf mem allocator for LPM trie

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

On 2024-11-18 09:08:05 [+0800], Hou Tao wrote:
> diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c
> index d447a6dab83b..d8995acecedf 100644
> --- a/kernel/bpf/lpm_trie.c
> +++ b/kernel/bpf/lpm_trie.c
> @@ -319,6 +326,25 @@ static int trie_check_noreplace_update(const struct lpm_trie *trie, u64 flags)
>  	return 0;
>  }
>  
> +static void lpm_trie_node_free(struct lpm_trie *trie,
> +			       struct lpm_trie_node *node, bool defer)
> +{
> +	struct bpf_mem_alloc *ma;
> +
> +	if (!node)
> +		return;
> +
> +	ma = (node->flags & LPM_TREE_NODE_FLAG_ALLOC_LEAF) ? trie->leaf_ma :
> +							     trie->im_ma;
> +
> +	migrate_disable();
> +	if (defer)
> +		bpf_mem_cache_free_rcu(ma, node);
> +	else
> +		bpf_mem_cache_free(ma, node);
> +	migrate_enable();

I guess a preempt_disable() here instead wouldn't hurt much. The inner
pieces of the allocator (unit_free()) does local_irq_save() for the
entire function so we don't win much with migrate_disable().

> +}
> +

Sebastian