[BUG] conflicting types for '____ovs_dp_upcall'

[qingwusunny]

my probe code:

#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>

SEC("kprobe/ovs_dp_upcall")
int BPF_KPROBE(ovs_dp_upcall, struct datapath *dp, struct sk_buff *skb, const struct sw_flow_key *key,
        const struct dp_upcall_info *upcall_info, uint32_t cutlen)
{
    bpf_printk("ovs_dp_upcall point\n");
    return 0;
};

SEC("kretprobe/ovs_dp_upcall")
int BPF_KPROBE(ovs_dp_upcall_exit, long ret)
{
    bpf_printk("ovs_dp_upcall ret point ret=%d\n", ret);
    return 0;
};
char LICENSE[] SEC("license") = "Dual BSD/GPL";

And I run docker run -it -v `pwd`/:/src/ ghcr.io/eunomia-bpf/ecc-`uname -m`:latest failed, error and warning , error is conflicting types for '____ovs_dp_upcall':

/src/kprobe_ovs_dp_upcall.bpf.c:6:86: warning: declaration of 'struct sw_flow_key' will not be visible outside of this function [-Wvisibility]
int BPF_KPROBE(ovs_dp_upcall, struct datapath *dp, struct sk_buff *skb, const struct sw_flow_key *key,
                                                                                     ^
/src/kprobe_ovs_dp_upcall.bpf.c:7:22: warning: declaration of 'struct dp_upcall_info' will not be visible outside of this function [-Wvisibility]
        const struct dp_upcall_info *upcall_info, uint32_t cutlen)
                     ^
/src/kprobe_ovs_dp_upcall.bpf.c:6:38: warning: declaration of 'struct datapath' will not be visible outside of this function [-Wvisibility]
int BPF_KPROBE(ovs_dp_upcall, struct datapath *dp, struct sk_buff *skb, const struct sw_flow_key *key,
                                     ^
/src/kprobe_ovs_dp_upcall.bpf.c:6:86: warning: declaration of 'struct sw_flow_key' will not be visible outside of this function [-Wvisibility]
int BPF_KPROBE(ovs_dp_upcall, struct datapath *dp, struct sk_buff *skb, const struct sw_flow_key *key,
                                                                                     ^
/src/kprobe_ovs_dp_upcall.bpf.c:7:22: warning: declaration of 'struct dp_upcall_info' will not be visible outside of this function [-Wvisibility]
        const struct dp_upcall_info *upcall_info, uint32_t cutlen)
                     ^
/src/kprobe_ovs_dp_upcall.bpf.c:6:5: error: conflicting types for '____ovs_dp_upcall'
int BPF_KPROBE(ovs_dp_upcall, struct datapath *dp, struct sk_buff *skb, const struct sw_flow_key *key,
    ^
/tmp/.tmpG6eqsI/include/bpf/bpf_tracing.h:579:48: note: expanded from macro 'BPF_KPROBE'
static __always_inline typeof(name(0))                                      \
                                                                            ^
<scratch space>:17:1: note: expanded from here
____ovs_dp_upcall
^
/src/kprobe_ovs_dp_upcall.bpf.c:6:5: note: previous declaration is here
/tmp/.tmpG6eqsI/include/bpf/bpf_tracing.h:570:48: note: expanded from macro 'BPF_KPROBE'
static __always_inline typeof(name(0))                                      \
                                                                            ^
<scratch space>:8:1: note: expanded from here
____ovs_dp_upcall
^
6 warnings and 1 error generated.

[github-actions]

Thanks for using eunomia-bpf! We appreciate your help and we’ll take care of this as soon as possible.

[qingwusunny]

Can someone help me?

[Officeyutong]

#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>

SEC("kprobe/ovs_dp_upcall")
int BPF_KPROBE(ovs_dp_upcall, struct datapath *dp, struct sk_buff *skb, const struct sw_flow_key *key,
const struct dp_upcall_info *upcall_info, uint32_t cutlen)
{
bpf_printk("ovs_dp_upcall point\n");
return 0;
};

SEC("kretprobe/ovs_dp_upcall")
int BPF_KPROBE(ovs_dp_upcall_exit, long ret)
{
bpf_printk("ovs_dp_upcall ret point ret=%d\n", ret);
return 0;
};
char LICENSE[] SEC("license") = "Dual BSD/GPL";

Seems that the rootcause is the undefinition of struct datapath, sw_flow_key, dp_upcall_info. The expansion of macro KPROBE will produce a function proto like static inline __attribute__((always_inline)) typeof(ovs_dp_upcall(0)) ____ovs_dp_upcall(struct pt_regs *ctx, struct datapath *dp, struct sk_buff *skb, const struct sw_flow_key *key, const struct dp_upcall_info *upcall_info, uint32_t cutlen); , and the function implementation in the same signature. But since the structures were not predefined, but first-introduced in the function prototype, they are not visible by outer things. So in this way, clang treats the struct datapath* (and other struct pointers) as different types in the function proto and function implementation, and leads to a definition mismatch error