Re: [PATCH v2 ] devcoredump : Serialize devcd_del work

Johannes Berg
2022-04-25T17:20:13Z

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.

johannes