On Wed, 16 Oct 2019 14:39:20 +0800 Qu Wenruo <wqu@xxxxxxxx> wrote: > +static void print_uuid_arg(struct trace_seq *s, void *data, int size, > + struct tep_event *event, struct tep_print_arg *arg) > +{ > + const char *fmt; > + unsigned char *buf; > + > + fmt = "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x"; > + if (arg->type != TEP_PRINT_FIELD) { > + trace_seq_printf(s, "ARG TYPE NOT FIELID but %d", arg->type); > + return; > + } > + > + if (!arg->field.field) { > + arg->field.field = tep_find_any_field(event, arg->field.name); > + if (!arg->field.field) { > + do_warning("%s: field %s not found", > + __func__, arg->field.name); > + return; > + } > + } > + buf = data + arg->field.field->offset; You also need to make sure the data field is not smaller than 16 bytes. if (arg->field.field->size < 16) { trace_seq_puts(s, "INVALIDUUID"); return; } > + > + trace_seq_printf(s, fmt, buf[0], buf[1], buf[2], buf[3], buf[4], buf[5], > + buf[6], buf[7], buf[8], buf[9], buf[10], buf[11], buf[12], > + buf[13], buf[14], buf[15]); > +} > + Hmm, I know print_mac_addr() does something similar as this, but this is getting a bit extreme (too many arguments!). What about doing: for (i = 0; i < 4; i++) trace_seq_printf(s, "%02x", buf++); for (i = 0; i < 3; i++) trace_seq_printf(s, "-%02x%02x", buf[i * 2], buf[i * 2 + 1]); buf += 6; trace_seq_putc(s, '-'); for (i = 0; i < 6; i++) trace_seq_printf(s, "%02x", buf++); Hmm, not sure the above is better, but having that many arguments just looks ugly to me. -- Steve