tools: Update tcpdrop error message when the probe fails

When tcpdrop tool fails to attach a kprobe to tcp_drop() function, the
error message suggest that the running kernel is too old. However,
tcp_drop() is a relatively small static function, so nowadays, it's
more likely that it has been inlined.

Update the error message to avoid to confuse the user.

Signed-off-by: Jerome Marchand <[email protected]>

tools/tcpdrop.py

@@ -200,7 +200,7 @@ def print_ipv6_event(cpu, data, size):
  b.attach_kprobe(event="tcp_drop", fn_name="trace_tcp_drop")
 else:
  print("ERROR: tcp_drop() kernel function not found or traceable. "
- "Older kernel versions not supported.")
+ "The kernel might be too old or the the function has been inlined.")
  exit()
 stack_traces = b.get_table("stack_traces")