Re: [PATCH] device property: Make modifications of fwnode "flags" thread safe

Andy Shevchenko
2026-03-17T07:34:29Z

On Tue, Mar 17, 2026 at 08:26:53AM +0100, Wolfram Sang wrote:

...

> Thanks for tackling this issue! I agree it should be fixed, just
> wondered about one thing:
>
> > While flags are often modified while under the "fwnode_link_lock",
> > this is not universally true.
>
> Is it a possibility to use the lock in all code paths instead?
> Because...
>
> > struct list_head consumers;
> > - u8 flags;
> > + unsigned long flags;
>
> ... this change costs some memory on every system. Maybe it can be
> avoided?

How much memory does it cost? On most 64-bit architectures is +4 bytes,
rarely +0 bytes, on m68k it might be +2bytes. On 32-bit it most likely
+0 bytes. I expect that 64-bit machines will cope with this bump.

--
With Best Regards,
Andy Shevchenko