[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH 2/2] xen: rename wrong named pfn related variables
On 30.07.2021 11:00, Juergen Gross wrote: > On 16.06.21 12:43, Juergen Gross wrote: >> On 16.06.21 11:56, Jan Beulich wrote: >>> On 16.06.2021 09:30, Juergen Gross wrote: >>>> --- a/arch/x86/xen/p2m.c >>>> +++ b/arch/x86/xen/p2m.c >>>> @@ -95,8 +95,8 @@ unsigned long *xen_p2m_addr __read_mostly; >>>> EXPORT_SYMBOL_GPL(xen_p2m_addr); >>>> unsigned long xen_p2m_size __read_mostly; >>>> EXPORT_SYMBOL_GPL(xen_p2m_size); >>>> -unsigned long xen_max_p2m_pfn __read_mostly; >>>> -EXPORT_SYMBOL_GPL(xen_max_p2m_pfn); >>>> +unsigned long xen_p2m_max_size __read_mostly; >>>> +EXPORT_SYMBOL_GPL(xen_p2m_max_size); >>> >>> Instead of renaming the exported variable (which will break consumers >>> anyway), how about dropping the apparently unneeded export at this >>> occasion? >> >> Why do you think it isn't needed? It is being referenced via the inline >> function __pfn_to_mfn() in arch/x86/include/asm/xen/page.h. And >> __pfn_to_mfn() is used via lots of other inline functions and macros. >> >>> Further it looks to me as if xen_p2m_size and this variable >>> were actually always kept in sync, so I'd like to put up the question >>> of dropping one of the two. >> >> Hmm, should be possible, yes. > > Looking into this it seems this is not possible. > > xen_p2m_size always holds the number of p2m entries in the p2m table, > including invalid ones at the end. xen_p2m_pfn_limit however contains > the (rounded up) index after the last valid p2m entry. I'm afraid I can't follow: xen_build_dynamic_phys_to_machine() sets xen_p2m_size and then syncs its value to what so far has been xen_max_p2m_pfn. xen_vmalloc_p2m_tree() sets xen_max_p2m_pfn and then syncs its value to xen_p2m_size. I therefore can't see how the two values would hold different values, except for the brief periods between updating one and then the other. Jan
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