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

From: Andy Shevchenko

Date: Tue Mar 17 2026 - 04:05:26 EST


On Tue, Mar 17, 2026 at 08:42:08AM +0100, Wolfram Sang wrote:

> > > ... 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.
>
> I am not opposing that the issue should be fixed. If it is not possible
> to take the lock everywhere, this is a proper solution. But if we don't
> have to use more memory, then we could save it. Our new SoC easily has
> 'struct device' in the hundreds.

What's the alignment for the u8 member in your SoC? 4 bytes or 8 bytes?
(I assume it's 64-bit SoC.)

--
With Best Regards,
Andy Shevchenko