Re: [PATCH 0/9] Generate uevents for all DM events

From: Mike Snitzer <snitzer@redhat.com>
To: Andy Grover <agrover@redhat.com>
Cc: gregkh@linuxfoundation.org, dm-devel@redhat.com,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/9] Generate uevents for all DM events
Date: Mon, 3 Oct 2016 15:29:13 -0400	[thread overview]
Message-ID: <20161003192913.GA7044@redhat.com> (raw)
In-Reply-To: <1475522580-16723-1-git-send-email-agrover@redhat.com>

On Mon, Oct 03 2016 at  3:22pm -0400,
Andy Grover <agrover@redhat.com> wrote:

> Hi Mike and GregKH,
> 
> I want a way to get devicemapper events without using the DM ioctl,
> because that requires creating a thread to sleep in the ioctl for each
> dm device I want events from.
> 
> It would seem like using uevents and KOBJ_CHANGE would be a good way
> to do this, but Mike said that the uevent maintainers (Greg that's
> you?) did not think this was a good idea?

I think you might be confusing me with Alasdair?

> If so, I was hoping you could talk a little more about why -- grep
> shows KOBJ_CHANGE used all over, but its usage is not documented in
> kobject.txt. In any case I can update kobject.txt with some more
> guidelines.
> 
> The following patchset may be appliable if you're actually ok with
> using KOBJ_CHANGE for dm events, or if not, then I'll look to rework
> it to use a dm-specific genetlink approach.

I don't have strong opinions on this.  If Greg is OK with your approach
we can move forward (bringing Alasdair into the discussion too).

That said I haven't looked at your changes.  But your subjects make for
a confusing mix of "uevent" and "event".  Could just be that I'm too far
removed from the details to appreciate what is happening.

Mike

> Andy Grover (9):
>   dm: Do not export dm_send_uevents
>   dm: Move multipath-specific stuff out of dm-uevent.c
>   dm: Inline dm_build_path_uevent into dm_path_uevent
>   dm: Update dm-uevent.txt
>   dm: Rename dm_build_uevent to dm_uevent_build
>   dm: Rename dm_event_add to dm_event_queue
>   dm: Implement dm_uevent_add()
>   dm: Generate uevents for thin targets
>   dm: Generate uevents for other targets
> 
>  Documentation/device-mapper/dm-uevent.txt |  54 ++++++++++++++--
>  drivers/md/dm-cache-target.c              |   5 +-
>  drivers/md/dm-log-userspace-base.c        |   8 ++-
>  drivers/md/dm-log.c                       |   1 +
>  drivers/md/dm-mpath.c                     |  56 ++++++++++++++++
>  drivers/md/dm-raid1.c                     |   1 +
>  drivers/md/dm-snap.c                      |   1 +
>  drivers/md/dm-thin.c                      |   3 +
>  drivers/md/dm-uevent.c                    | 102 ++++++++++--------------------
>  drivers/md/dm-uevent.h                    |  30 +++++++--
>  drivers/md/dm.c                           |   3 +-
>  include/linux/device-mapper.h             |   3 +-
>  12 files changed, 180 insertions(+), 87 deletions(-)
> 
> -- 
> 2.7.4
> 