execsnoop warning

Looks like execsnoop is throwing a warning:

matty@theshack ~] sudo execsnoop
In file included from /virtual/main.c:4:
include/linux/fs.h:2653:9: warning: comparison of unsigned enum expression < 0
is always false [-Wtautological-compare]
if (id < 0 || id >= READING_MAX_ID)
~~ ^ ~

Not sure if this is intentional but I figured I would pass it on. Killer script!

Start by reproducing the warning with the reported `sudo execsnoop` command, then inspect `include/linux/fs.h` around line 2653 and the execsnoop entry point. Determine whether the unsigned-enum comparison is intentional and document or correct the warning so the command runs without it.

Written by the indexing model from the issue text.