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

From: Andy Shevchenko <[email-masked]>
Date: Tue, 17 Mar 2026 09:34:17 +0200

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