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

[Brendan Gregg]

On Wed, Aug 13, 2014 at 12:57 AM, Alexei Starovoitov <ast@xxxxxxxxxxxx> 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
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