linux-kernel - [PATCH 1/2] bpf: Fix register_bpf_struct

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Message-ID: <ead27aa92275c71c1fcd148f88ca6926a524f322.1764843951.git.geert@linux-m68k.org>
Date: Thu,  4 Dec 2025 11:29:15 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Kui-Feng Lee <thinker.li@...il.com>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	"D . Wythe" <alibuda@...ux.alibaba.com>,
	Dust Li <dust.li@...ux.alibaba.com>,
	Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	John Fastabend <john.fastabend@...il.com>,
	Sidraya Jayagond <sidraya@...ux.ibm.com>,
	Wenjia Zhang <wenjia@...ux.ibm.com>,
	Mahanta Jambigi <mjambigi@...ux.ibm.com>,
	Tony Lu <tonylu@...ux.alibaba.com>,
	Wen Gu <guwen@...ux.alibaba.com>,
	"David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Simon Horman <horms@...nel.org>
Cc: bpf@...r.kernel.org,
	linux-rdma@...r.kernel.org,
	linux-s390@...r.kernel.org,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH 1/2] bpf: Fix register_bpf_struct_ops() dummy

If CONFIG_BPF_SYSCALL=y, but CONFIG_BPF_JIT=n:

    net/smc/smc_hs_bpf.c: In function ‘bpf_smc_hs_ctrl_init’:
    include/linux/bpf.h:2068:50: error: statement with no effect [-Werror=unused-value]
     2068 | #define register_bpf_struct_ops(st_ops, type) ({ (void *)(st_ops); 0; })
	  |                                                  ^~~~~~~~~~~~~~~~
    net/smc/smc_hs_bpf.c:139:16: note: in expansion of macro ‘register_bpf_struct_ops’
      139 |         return register_bpf_struct_ops(&bpf_smc_hs_ctrl_ops, smc_hs_ctrl);
	  |                ^~~~~~~~~~~~~~~~~~~~~~~

As type is not a variable, but a variable type, this cannot be fixed by
just converting register_bpf_struct_ops() into a static inline function.
Hence fix this by introducing a static inline intermediate dummy.

Fixes: f6be98d19985411c ("bpf, net: switch to dynamic registration")
Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
---
 include/linux/bpf.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 6498be4c44f8c275..bb69905c28a761e7 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2065,7 +2065,11 @@ int bpf_struct_ops_desc_init(struct bpf_struct_ops_desc *st_ops_desc,
 void bpf_map_struct_ops_info_fill(struct bpf_map_info *info, struct bpf_map *map);
 void bpf_struct_ops_desc_release(struct bpf_struct_ops_desc *st_ops_desc);
 #else
-#define register_bpf_struct_ops(st_ops, type) ({ (void *)(st_ops); 0; })
+static inline int __register_bpf_struct_ops(struct bpf_struct_ops *st_ops)
+{
+	return 0;
+}
+#define register_bpf_struct_ops(st_ops, type) __register_bpf_struct_ops(st_ops)
 static inline bool bpf_try_module_get(const void *data, struct module *owner)
 {
 	return try_module_get(owner);
-- 
2.43.0