Re: [PATCH v1 1/2] pid: add pidfd_open()

On 2019-05-16, Oleg Nesterov oleg@redhat.com wrote:

On 05/16, Christian Brauner wrote:

...

With the introduction of pidfds through CLONE_PIDFD it is possible to created pidfds at process creation time.

Now I am wondering why do we need CLONE_PIDFD, you can just do

pid = fork(); pidfd_open(pid);

While the race window would be exceptionally short, there is the possibility that the child will die and their pid will be recycled before you do pidfd_open(). CLONE_PIDFD removes the race completely.