Re: [PATCH v1 1/1] ACPI: utils: Fix reference counting in for_each_acpi_dev_match()

[Andy Shevchenko]

On Wed, May 26, 2021 at 1:29 AM Daniel Scally <djrscally@xxxxxxxxx> wrote:
> On 20/05/2021 20:40, Rafael J. Wysocki wrote:
> > On Thu, May 20, 2021 at 9:13 PM Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
> >> On Wed, May 19, 2021 at 11:19 PM Andy Shevchenko
> >> <andy.shevchenko@xxxxxxxxx> wrote:
> >>> Currently it's possible to iterate over the dangling pointer in case the device
> >>> suddenly disappears. This may happen becase callers put it at the end of a loop.
> >>>
> >>> Instead, let's move that call inside acpi_dev_get_next_match_dev().
> >> Not really.
> > OK, I see what you want to achieve and the macro is actually buggy,
> > because it leaves unbalanced references behind.
>
>
> Yeah; I guess the originally intended use (which was "get all these
> devices") doesn't really tally with the naming or with the operation of
> similar functions in the kernel like the fwnode_handle ops; sorry about
> that. Anyway; I think Andy's fix is the right way to do it, so the
> calling code's responsible for holding onto a reference if it wants to
> keep it.

I think we need to postpone the fix till v5.14-rc1 is out. It appears
that some code has been changed in EFI and media subsystems so that
patch will be in conflict with.


-- 
With Best Regards,
Andy Shevchenko