Re: [PATCH v2 ] devcoredump : Serialize devcd_del work

[Mukesh Ojha]

On 4/26/2022 1:07 AM, Thomas Gleixner wrote:
> Cc+: Kees
>
> On Mon, Apr 25 2022 at 19:19, Johannes Berg wrote:
> > On Mon, 2022-04-25 at 19:00 +0200, Thomas Gleixner wrote:
> > > Johannes, can you please explain whether this immediate flush in
> > > disabled_store() is really required and if so, why?
> > I don't really know, as I remember that requirement (or maybe even code,
> > not sure) came from Kees, who needed the lockdown.
> >
> > Given the use case (ChromeOS?) I'm not sure I see a need to flush all of
> > them, since I guess a typical system would set the lockdown early in
> > boot and hopefully not have a crash-dump around already.
> >
> > That said, I don't think the diagram you made works - fn() during the
> > iteration is guaranteed to be invoked with a reference of its own, so
> > the put_device() there can't be the last reference, only as fn() returns
> > you'd put the last reference *there*, freeing it.
>
> Bah, you are right, it's magically protected by the klist ref, which
> prevents devcd from going away. Damned obvious.
>
> This really needs comments why this all can magically "work".
>
> Thanks,
>
>          tglx

Thanks you all for your time in reviewing this.
I tried to address few comments in v3 here.

https://lore.kernel.org/lkml/1650981343-11739-1-git-send-email-quic_mojha@xxxxxxxxxxx/

While, we would like to hear from Kees about reason of immediate flush 
from disabled_store().

Regards,
-Mukesh
>