On Thu, Jun 10, 2021 at 3:19 AM Matthew Bobrowski [off-list ref] wrote:

Hey Jan/Amir/Christian,

Sending through v2 of the fanotify pidfd patch series. This series
contains the necessary fixes/suggestions that had come out of the
previous discussions, which can be found here [0], here [1], and here
[3].

The main difference in this series is that we perform pidfd creation a
little earlier on i.e. in copy_event_to_user() so that clean up of the
pidfd can be performed nicely in the event of an info
generation/copying error. Additionally, we introduce two errors. One
being FAN_NOPIDFD, which is supplied to the listener in the event that
a pidfd cannot be created due to early process termination. The other
being FAN_EPIDFD, which will be supplied in the event that an error
was encountered during pidfd creation.

Please let me know what you think.

[0]
https://lore.kernel.org/linux-fsdevel/48d18055deb4617d97c695a08dca77eb57309\
7e9.1621473846.git.repnop@google.com/

[1]
https://lore.kernel.org/linux-fsdevel/24c761bd0bd1618c911a392d0c310c24da7d8\
941.1621473846.git.repnop@google.com/

[2]
https://lore.kernel.org/linux-fsdevel/48d18055deb4617d97c695a08dca77eb57309\
7e9.1621473846.git.repnop@google.com/


Matthew Bobrowski (5):
  kernel/pid.c: remove static qualifier from pidfd_create()
  kernel/pid.c: implement additional checks upon pidfd_create()
    parameters
  fanotify/fanotify_user.c: minor cosmetic adjustments to fid labels
  fanotify/fanotify_user.c: introduce a generic info record copying
    helper

Above fanotify commits look good to me.
Please remove /fanotify_user.c from commit titles and use 'pidfd:' for
the pidfd commit titles.

  fanotify: add pidfd support to the fanotify API

This one looks mostly fine. Gave some minor comments.

The biggest thing I am missing is a link to an LTP test draft and
man page update draft.

In general, I think it is good practice to provide a test along with any
fix, but for UAPI changes we need to hold higher standards - both the
test and man page draft should be a must before merge IMO.

We already know there is going to be a clause about FAN_NOPIDFD
and so on... I think it is especially hard for people on linux-api list to
review a UAPI change without seeing the contract in a user manual
format. Yes, much of the information is in the commit message, but it
is not the same thing as reading a user manual and verifying that the
contract makes sense to a programmer.

Thanks,
Amir.