[RESEND][PATCH bpf-next] bpf: Check map->record at the beginning of check_and_free_fields()

[RESEND][PATCH bpf-next] bpf: Check map->record at the beginning of check_and_free_fields()

[Hou Tao]

From: Hou Tao <houtao1@huawei.com>

When there are no special fields in the map value, there is no need to
invoke bpf_obj_free_fields(). Therefore, checking the validity of
map->record in advance.

After the change, the benchmark result of the per-cpu update case in
map_perf_test increased by 40% under a 16-CPU VM.

Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 kernel/bpf/hashtab.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index c308300fc72f6..877298133fdae 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -787,6 +787,9 @@ static int htab_lru_map_gen_lookup(struct bpf_map *map,
 static void check_and_free_fields(struct bpf_htab *htab,
 				  struct htab_elem *elem)
 {
+	if (IS_ERR_OR_NULL(htab->map.record))
+		return;
+
 	if (htab_is_percpu(htab)) {
 		void __percpu *pptr = htab_elem_get_ptr(elem, htab->map.key_size);
 		int cpu;
-- 
2.29.2

Re: [RESEND][PATCH bpf-next] bpf: Check map->record at the beginning of check_and_free_fields()

[Kumar Kartikeya Dwivedi]

On Sat, 15 Mar 2025 at 15:57, Hou Tao <houtao@huaweicloud.com> wrote:
>
> From: Hou Tao <houtao1@huawei.com>
>
> When there are no special fields in the map value, there is no need to
> invoke bpf_obj_free_fields(). Therefore, checking the validity of
> map->record in advance.
>
> After the change, the benchmark result of the per-cpu update case in
> map_perf_test increased by 40% under a 16-CPU VM.
>
> Signed-off-by: Hou Tao <houtao1@huawei.com>
> ---

Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

Re: [RESEND][PATCH bpf-next] bpf: Check map->record at the beginning of check_and_free_fields()

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Sat, 15 Mar 2025 23:09:30 +0800 you wrote:
> From: Hou Tao <houtao1@huawei.com>
> 
> When there are no special fields in the map value, there is no need to
> invoke bpf_obj_free_fields(). Therefore, checking the validity of
> map->record in advance.
> 
> After the change, the benchmark result of the per-cpu update case in
> map_perf_test increased by 40% under a 16-CPU VM.
> 
> [...]

Here is the summary with links:
  - [RESEND,bpf-next] bpf: Check map->record at the beginning of check_and_free_fields()
    https://git.kernel.org/bpf/bpf-next/c/bb2243f4328b

You are awesome, thank you!
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