Re: [PATCH v17 13/32] x86,fs/resctrl: Add an architectural hook called for each mount

[Luck, Tony]

On Mon, Jan 05, 2026 at 08:17:11PM +0100, Borislav Petkov wrote:
> On Wed, Dec 17, 2025 at 09:21:00AM -0800, Tony Luck wrote:
> > +void resctrl_arch_pre_mount(void)
> > +{
> > +	static atomic_t only_once = ATOMIC_INIT(0);
> > +	int old = 0;
> > +
> > +	if (!atomic_try_cmpxchg(&only_once, &old, 1))
> > +		return;
> > +}
> 
> There's
> 
> #define DO_ONCE(func, ...)
> 
> Can't use that?

Learn something new every day. Yes, <linux/once.h> looks possible here.

Though I believe I'll need the DO_ONCE_SLEEPABLE() version since 
resctrl_arch_pre_mount() grabs a mutex and various called functions
allocate memory using kmalloc().

-Tony