Re: [PATCH bpf-next v2 3/3] bpf: Move nf_conn extern declarations to filter.h

From: Martin KaFai Lau
Date: Tue Sep 20 2022 - 01:21:47 EST


On 9/19/22 12:44 PM, Daniel Xu wrote:
We're seeing the following new warnings on netdev/build_32bit and
netdev/build_allmodconfig_warn CI jobs:

../net/core/filter.c:8608:1: warning: symbol
'nf_conn_btf_access_lock' was not declared. Should it be static?
../net/core/filter.c:8611:5: warning: symbol 'nfct_bsa' was not
declared. Should it be static?

Fix by ensuring extern declaration is present while compiling filter.o.

Fixes: 864b656f82cc ("bpf: Add support for writing to nf_conn:mark")
Signed-off-by: Daniel Xu <dxu@xxxxxxxxx>
---
include/linux/filter.h | 6 ++++++
include/net/netfilter/nf_conntrack_bpf.h | 7 +------
2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 75335432fcbc..98e28126c24b 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -567,6 +567,12 @@ struct sk_filter {
DECLARE_STATIC_KEY_FALSE(bpf_stats_enabled_key);
+extern struct mutex nf_conn_btf_access_lock;
+extern int (*nfct_btf_struct_access)(struct bpf_verifier_log *log, const struct btf *btf,
+ const struct btf_type *t, int off, int size,
+ enum bpf_access_type atype, u32 *next_btf_id,
+ enum bpf_type_flag *flag);
+
typedef unsigned int (*bpf_dispatcher_fn)(const void *ctx,
const struct bpf_insn *insnsi,
unsigned int (*bpf_func)(const void *,
diff --git a/include/net/netfilter/nf_conntrack_bpf.h b/include/net/netfilter/nf_conntrack_bpf.h
index d1087e4da440..24d1ccc1f8df 100644
--- a/include/net/netfilter/nf_conntrack_bpf.h
+++ b/include/net/netfilter/nf_conntrack_bpf.h
@@ -5,6 +5,7 @@
#include <linux/bpf.h>
#include <linux/btf.h>
+#include <linux/filter.h>

The filter.h is only needed by nf_conntrack_bpf.c? How about moving this include to nf_conntrack_bpf.c. nf_conntrack_bpf.h is included by other conntrack core codes. I would prefer not to spill over unnecessary bpf headers to them. The same goes for the above bpf.h and btf.h which are only needed in nf_conntrack_bpf.c also?

#include <linux/kconfig.h>
#include <linux/mutex.h>

Also, is mutex.h still needed?

@@ -14,12 +15,6 @@
extern int register_nf_conntrack_bpf(void);
extern void cleanup_nf_conntrack_bpf(void);
-extern struct mutex nf_conn_btf_access_lock;
-extern int (*nfct_btf_struct_access)(struct bpf_verifier_log *log, const struct btf *btf,
- const struct btf_type *t, int off, int size,
- enum bpf_access_type atype, u32 *next_btf_id,
- enum bpf_type_flag *flag);
-
#else
static inline int register_nf_conntrack_bpf(void)