On Fri, Apr 24, 2020 at 12:54 PM Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote: > > The problem with > > remove > remove > add > add > is: > > A lookup that hit between the remove and the add could return nothing. Argh. Because that thing doesn't actually _search_ the list, it just wants to pick any (first) entry. So it doesn't actually care what it gets, just that it gets something. Ok, I see. > For PIDTYPE_PID and PIDTYPE_TGID these practically aren't lists but > pointers to the appropriate task. Only for PIDTYPE_PGID and PIDTYPE_SID > do these become lists in practice. Yeah, that's what confused me. Ok, please add a comment about the "single-entry list" issue, and I'm happy. Linus