bpf_trace_printk isn't working

["MD I. Islam" <tamim@xxxxxxxxxxx>]

Hi

I have following code attached to an interface:

SEC("simple")
int handle_ingress(struct __sk_buff *skb)
{
        unsigned char *data = (unsigned char *)(long)skb->data;
        char fmt[] = "%u\n";
        bpf_trace_printk(fmt, sizeof(fmt), *data);
        return 0;
}

When packets pass through the interface, it does not print anything at
/sys/kernel/debug/tracing/trace_pipe. However if I do
bpf_trace_printk(fmt, sizeof(fmt), data), it prints the pointer. Could
you please advise what is wrong here?

Many thanks
Tamim