Messages in this thread | | | Date | Thu, 18 Feb 2016 10:59:05 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v11 3/4] x86, mce: Add __mcsafe_copy() |
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On Thu, Feb 18, 2016 at 09:21:07AM +0100, Ingo Molnar wrote: > > * Tony Luck <tony.luck@intel.com> wrote: > > > Make use of the EXTABLE_FAULT exception table entries. This routine > > returns a structure to indicate the result of the copy: > > So the series looks good to me, but I have some (mostly readability) comments that > went beyond what I usually fix up manually: > > > struct mcsafe_ret { > > u64 trapnr; > > u64 remain; > > }; > > > +struct mcsafe_ret { > > + u64 trapnr; > > + u64 remain; > > +}; > > Yeah, so please change this to something like: > > struct mcsafe_ret { > u64 trap_nr; > u64 bytes_left; > }; > > this makes it crystal clear what the fields are about and what their unit is. > Readability is king and modern consoles are wide enough, no need to abbreviate > excessively.
I prefer to use my modern console width to display multiple columns of text, instead of wasting it to display mostly whitespace. Therefore I still very much prefer ~80 char wide code.
> > +struct mcsafe_ret __mcsafe_copy(void *dst, const void __user *src, size_t cnt); > > +extern void __mcsafe_copy_end(void); > > So this is a bad name I think. What kind of 'copy' is this? It's defined in > asm/string_64.h - so people might thing it's a string copy. If it's a memcpy > variant then name it so. > > Also, I'd suggest we postfix the new mcsafe functions with '_mcsafe', not prefix > them. Special properties of memcpy routines are usually postfixes - such as > _nocache(), _toio(), etc.
I think the whole notion of mcsafe here is 'wrong'. This copy variant simply reports the kind of trap that happened (#PF or #MC) and could arguably be extended to include more types if the hardware were to generate more.
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