Messages in this thread | | | Subject | Re: [PATCH v4] do_wait: make PIDTYPE_PID case O(1) instead of O(n) | From | Jim Newsome <> | Date | Fri, 12 Mar 2021 10:51:29 -0600 |
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On 3/12/21 10:41, Oleg Nesterov wrote: > On 03/11, Jim Newsome wrote: >> + >> + if (target && is_effectively_child(wo, ptrace, target)) { >> + retval = wait_consider_task(wo, ptrace, target); > No, this is not right... You need to check target->ptrace != 0.
Shoot; got lost in the shuffle. Sorry about that and thanks for catching!
> I know that Eric suggests to not use thread_group_leader() and I won't argue > even if I don't really agree. > > Up to you, but to me something like > > do_wait_pid() > { > target = pid_task(wo->wo_pid, PIDTYPE_PID); > > if (!target) > return 0; > > if (thread_group_leader(target) && > is_effectively_child(wo, 0, target) { > ... > } > > if (target->ptrace && > is_effectively_child(wo, 1, target) { > ... > } > > return 0; > > } > > looks more simple/clean.
I like that a little better too. I'll go this way since Eric seemed Ok with either way.
If we do that then it might make sense to move the `thread_group_leader` filter into `is_effectively_child`, but maybe that obscures what the latter is doing too much. It'd at least have to be renamed, and I'm not sure of a clear name that'd capture exactly what it's doing. Maybe `is_valid_waitee`?
If I don't hear anything I'll just go with how you've already proposed.
v5 coming in a bit. I'll drop your (Oleg's) reviewed-by since it's changed substantially since then.
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