Re: [PATCH v5] pidfd: add ioctl to retrieve pid info
From: Oleg Nesterov
Date: Sun Oct 06 2024 - 14:56:10 EST
On 10/06, Luca Boccassi wrote:
>
> I see, so what should I do here then? Check both? Or none?
I don't know, because I don't know how are you going to use this API.
> The caller
> needs to verify that the data is still valid at the point they use it
> anyway,
So "none" should work fine? Just it should be documented that, say,
kinfo.pid can be 0 if we race with the exiting task.
Just in case, you can also use lock_task_sighand() || return -ESRCH,
this way kinfo.*pid can't be zero. But I don't think this will buy too
much, the task can exit right after pidfd_info() returns.
Oleg.