Messages in this thread | | | From | "Huang, Kai" <> | Subject | Re: [PATCH 1/4] x86/cpu: Add and use new CPUID region helper | Date | Wed, 3 Apr 2024 10:33:39 +0000 |
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On Tue, 2024-04-02 at 10:13 -0700, Dave Hansen wrote: > On 3/25/24 05:24, Huang, Kai wrote: > > > > Nit: > > > > > + > > > +/* Returns true if the leaf exists and @value was populated */ > > > > ^ is ? > > It's a subtle difference, but I think it's better as I wrote it. > Returning true happens *after* the value _was_ populated. > > > > +static inline bool get_cpuid_region_leaf(u32 leaf, enum cpuid_regs_idx reg, > > > + u32 *value) > > > +{ > > > + u16 region = leaf >> 16; > > > + u32 regs[4]; > > > + > > > + if (cpuid_region_max_leaf(region) < leaf) > > > + return false; > > > + > > > + cpuid(leaf, ®s[CPUID_EAX], ®s[CPUID_EBX], > > > + ®s[CPUID_ECX], ®s[CPUID_EDX]); > > > + > > > + *value = regs[reg]; > > > + > > > + return true; > > > +} > > > > I found despite the get_cpuid_region_leaf() returns true/false, the return value > > is never used in this series. Instead, this series uses below pattern: > > > > u32 data = 0; /* explicit initialization */ > > > > get_cpuid_region_leaf(leaf, ..., &data); > > > > Which kinda implies the 'data' won't be touched if the requested leaf isn't > > supported I suppose? > > > > Since the return value is never used, should we consider just making this > > function void? > > I certainly considered it. > > But I do think that get_cpuid_region_leaf() looks a lot more obviously > correct and useful when it explicitly returns what it did, even if the > existing callers don't take advantage of it. > > I suspect it generates the same code either way.
Agreed:
Reviewed-by: Kai Huang <kai.huang@intel.com>
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