[PATCH bpf-next] bpf: Only call sock_from_file with CONFIG_NET

[Florent Revest <revest@xxxxxxxxxxxx>]

This avoids
  ld: kernel/trace/bpf_trace.o: in function `bpf_sock_from_file':
  bpf_trace.c:(.text+0xe23): undefined reference to `sock_from_file'
When compiling a kernel with BPF and without NET.

Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Signed-off-by: Florent Revest <revest@xxxxxxxxxxxx>
---
 kernel/trace/bpf_trace.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 0cf0a6331482..877123bae71f 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1272,7 +1272,11 @@ const struct bpf_func_proto bpf_snprintf_btf_proto = {
 
 BPF_CALL_1(bpf_sock_from_file, struct file *, file)
 {
+#ifdef CONFIG_NET
 	return (unsigned long) sock_from_file(file);
+#else
+	return NULL;
+#endif
 }
 
 BTF_ID_LIST(bpf_sock_from_file_btf_ids)
-- 
2.29.2.576.ga3fc446d84-goog