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Date: Thu, 18 Feb 2016 10:12:42 -0800 From: Linus Torvalds <torvalds@...ux-foundation.org> To: Tony Luck <tony.luck@...el.com> Cc: Ingo Molnar <mingo@...nel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org> Subject: Re: [PATCH v11 3/4] x86, mce: Add __mcsafe_copy() On Wed, Feb 17, 2016 at 10:20 AM, Tony Luck <tony.luck@...el.com> wrote: > > If we faulted during the copy, then 'trapnr' will say which type > of trap (X86_TRAP_PF or X86_TRAP_MC) and 'remain' says how many > bytes were not copied. So apart from the naming, a couple of questions: - I'd like to see the actual *use* case explained, not just what it does. - why does this use the complex - and slower, on modern machines - unrolled manual memory copy, when you might as well just use a single rep ; movsb which not only makes it smaller, but makes the exception fixup trivial. - why not make the "bytes remaining" the same as for a user-space copy (ie return it as the return value)? - at that point, it ends up looking a *lot* like uaccess_try/catch, which gets the error code from current_thread_info()->uaccess_err Hmm? Linus
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