netdev - [PATCH bpf-next] bpf, x86: remove unnecessary handling of BPF

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Date:   Thu, 27 Jan 2022 16:32:40 +0800
From:   Hou Tao <houtao1@...wei.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        John Fastabend <john.fastabend@...il.com>
CC:     Martin KaFai Lau <kafai@...com>, Yonghong Song <yhs@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Brendan Jackman <jackmanb@...gle.com>,
        <netdev@...r.kernel.org>, <bpf@...r.kernel.org>,
        <houtao1@...wei.com>
Subject: [PATCH bpf-next] bpf, x86: remove unnecessary handling of BPF_SUB atomic op

According to the LLVM commit (https://reviews.llvm.org/D72184),
sync_fetch_and_sub() is implemented as a negation followed by
sync_fetch_and_add(), so there will be no BPF_SUB op and just
remove it.

Signed-off-by: Hou Tao <houtao1@...wei.com>
---
 arch/x86/net/bpf_jit_comp.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index ce1f86f245c9..5d643ebb1e56 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -787,7 +787,6 @@ static int emit_atomic(u8 **pprog, u8 atomic_op,
 	/* emit opcode */
 	switch (atomic_op) {
 	case BPF_ADD:
-	case BPF_SUB:
 	case BPF_AND:
 	case BPF_OR:
 	case BPF_XOR:
-- 
2.29.2