Re: [PATCH v3 0/2] drm: Add GPU reset sysfs

André Almeida
2022-11-30T15:24:13Z

On 11/28/22 06:30, Simon Ser wrote:
> The PID is racy, the user-space daemon could end up killing an
> unrelated process… Is there any way we could use a pidfd instead?

Is the PID race condition something that really happens or rather
something theoretical?

Anyway, I can't see how pidfd and uevent would work together. Since
uevent it's kind of a broadcast and pidfd is an anon file, it wouldn't
be possible to say to userspace which is the fd to be used giving that
file descriptors are per process resources.

On the other hand, this interface could be converted to be an ioctl that
userspace would block waiting for a reset notification, then the kernel
could create a pidfd and give to the blocked process the right fd. We
would probably need a queue to make sure no event is lost.

Thanks
André