optimize code, remove unnecessary filter check

tools/offcputime

@@ -92,22 +92,22 @@ int offcpu(struct pt_regs *ctx) {
 
 int oncpu(struct pt_regs *ctx) {
  u32 pid = bpf_get_current_pid_tgid();
- FILTER
- u64 ts = bpf_ktime_get_ns();
- struct key_t key = {};
- u64 zero = 0, *val, bp = 0, *tsp, delta;
- int depth = 0;
+ u64 *tsp;
 
  // calculate delta time
  tsp = start.lookup(&pid);
  if (tsp == 0)
- return 0; // missed start
- delta = bpf_ktime_get_ns() - *tsp;
+ return 0; // missed start or filtered
+ u64 delta = bpf_ktime_get_ns() - *tsp;
  start.delete(&pid);
  delta = delta / 1000;
  if (delta < MINBLOCK_US)
  return 0;
 
+ // create map key
+ u64 zero = 0, *val, bp = 0;
+ int depth = 0;
+ struct key_t key = {};
  bpf_get_current_comm(&key.name, sizeof(key.name));
  bp = ctx->bp;