Re: [PATCH RFC v4 net-next 23/26] samples: bpf: elf file loader

On Wed, Aug 13, 2014 at 12:57 AM, Alexei Starovoitov [off-list ref] wrote:
[...]

+static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
+{
+       int fd, event_fd, err;
+       char fmt[32];
+       char path[256] = DEBUGFS;
+
+       fd = bpf_prog_load(BPF_PROG_TYPE_TRACING_FILTER, prog, size, license);
+
+       if (fd < 0) {
+               printf("err %d errno %d\n", fd, errno);
+               return fd;
+       }

Minor suggestion: since this is sample code, I'd always print the bpf
log after this this printf() error message:

printf("%s", bpf_log_buf);

Which has helped me debug my eBPF programs, as will be the case for
anyone hacking on the examples. Or have a function for logdie(), if
the log buffer may be populated with useful messages from other error
paths as well.

Brendan