RE: [PATCH] block: Check ADMIN before NICE for IOPRIO_CLASS_RT

[David Laight]

From: Alistair Delva
> Sent: 15 November 2021 19:09
...
> > > -                       if (!capable(CAP_SYS_NICE) && !capable(CAP_SYS_ADMIN))
> > > +                       if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_NICE))
> > >                                 return -EPERM;

Isn't the real problem that you actually want to test:
		if (!capable(CAP_SYS_NICE | CAP_SYS_ADMIN))
			return -EPERM;
so that you only get the fail 'splat' when neither is set.

This will be true whenever more than one capability enables something.

Possibly this needs something like:
int capabale_or(unsigned int, ...);
#define capabale_or(...) capabable_or(__VA_LIST__, ~0u)

	David

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