filemon should hold proctree_lock at least during pid check

[sjg]

Summary

filemon's pid check needs to guard against changes to proc tree while it is walking up the list.

[sjg]

Related to https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=200958

[kib]

sys/dev/filemon/filemon_wrapper.c

89

sx_slock should be enough there

89–90

This is wrong condition. You should use something like while (p != initproc).

97

This should be spelled p = proc_realparent(p);

[sjg]

implement suggested changes

[sjg]

missed the slock