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Date:   Mon, 9 Jan 2023 09:39:24 -0800
In-Reply-To: <20230108151258.96570-1-haiyue.wang@intel.com>
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Subject: Re: [PATCH bpf-next v1] bpf: Remove the unnecessary insn buffer comparison
From:   sdf@google.com
To:     Haiyue Wang <haiyue.wang@intel.com>
Cc:     bpf@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>, Hao Luo <haoluo@google.com>,
        Jiri Olsa <jolsa@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On 01/08, Haiyue Wang wrote:
> The variable 'insn' is initialized to 'insn_buf' without being changed,
> only some helper macros are defined, so the insn buffer comparison is
> unnecessary, just remove it.

> Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>

Acked-by: Stanislav Fomichev <sdf@google.com>

Looks like these should have been removed as part of commit 2377b81de527
("bpf: split shared bpf_tcp_sock and bpf_sock_ops implementation").

> ---
>   net/core/filter.c | 6 ------
>   1 file changed, 6 deletions(-)

> diff --git a/net/core/filter.c b/net/core/filter.c
> index ab811293ae5d..d9befa6ba04e 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -6847,9 +6847,6 @@ u32 bpf_tcp_sock_convert_ctx_access(enum  
> bpf_access_type type,
>   					FIELD));			\
>   	} while (0)

> -	if (insn > insn_buf)
> -		return insn - insn_buf;
> -
>   	switch (si->off) {
>   	case offsetof(struct bpf_tcp_sock, rtt_min):
>   		BUILD_BUG_ON(sizeof_field(struct tcp_sock, rtt_min) !=
> @@ -10147,9 +10144,6 @@ static u32 sock_ops_convert_ctx_access(enum  
> bpf_access_type type,
>   			SOCK_OPS_GET_FIELD(BPF_FIELD, OBJ_FIELD, OBJ);	      \
>   	} while (0)

> -	if (insn > insn_buf)
> -		return insn - insn_buf;
> -
>   	switch (si->off) {
>   	case offsetof(struct bpf_sock_ops, op):
>   		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_sock_ops_kern,
> --
> 2.39.0