linux-kernel - Re: [PATCH] x86, pmem: use memcpy_mcsafe() for memcpy_from

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Date:	Fri, 11 Mar 2016 15:50:01 -0700
From:	Ross Zwisler <ross.zwisler@...ux.intel.com>
To:	Dan Williams <dan.j.williams@...el.com>
Cc:	akpm@...ux-foundation.org, Ingo Molnar <mingo@...nel.org>,
	Tony Luck <tony.luck@...el.com>, linux-nvdimm@...ts.01.org,
	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org,
	Andy Lutomirski <luto@...capital.net>, linux-mm@...ck.org,
	Borislav Petkov <bp@...en8.de>,
	Ross Zwisler <ross.zwisler@...ux.intel.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] x86, pmem: use memcpy_mcsafe() for memcpy_from_pmem()

On Thu, Mar 10, 2016 at 11:15:53AM -0800, Dan Williams wrote:
> Update the definition of memcpy_from_pmem() to return 0 or -EIO on
> error.  Implement x86::arch_memcpy_from_pmem() with memcpy_mcsafe().
> 
> Cc: Borislav Petkov <bp@...en8.de>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: Tony Luck <tony.luck@...el.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Andy Lutomirski <luto@...capital.net>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Ross Zwisler <ross.zwisler@...ux.intel.com>
> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
> Andrew, now that all the pre-requisites for this patch are in -next
> (tip/core/ras, tip/x86/asm, nvdimm/libnvdimm-for-next) may I ask you to
> carry it in -mm?
> 
> Alternatively I can do an octopus merge and post a branch, but that
> seems messy/risky for me to be merging 3 branches that are still subject
> to a merge window disposition.
> 
>  arch/x86/include/asm/pmem.h |    9 +++++++++
>  drivers/nvdimm/pmem.c       |    4 ++--
>  include/linux/pmem.h        |   14 ++++++++------
>  3 files changed, 19 insertions(+), 8 deletions(-)
<>
> diff --git a/include/linux/pmem.h b/include/linux/pmem.h
> index 3ec5309e29f3..c46c5cf6538e 100644
> --- a/include/linux/pmem.h
> +++ b/include/linux/pmem.h
> @@ -66,14 +66,16 @@ static inline void arch_invalidate_pmem(void __pmem *addr, size_t size)
>  #endif
>  
>  /*
> - * Architectures that define ARCH_HAS_PMEM_API must provide
> - * implementations for arch_memcpy_to_pmem(), arch_wmb_pmem(),
> - * arch_copy_from_iter_pmem(), arch_clear_pmem(), arch_wb_cache_pmem()
> - * and arch_has_wmb_pmem().

Why did you delete the above comment?  I believe it adds value?  Or do you
think the fact that another architecture will get compile errors if the arch_*
functions aren't defined is documentation enough?

> + * memcpy_from_pmem - read from persistent memory with error handling
> + * @dst: destination buffer
> + * @src: source buffer

Missing kerneldoc for @size?

Aside from those tiny nits:
Reviewed-by: Ross Zwisler <ross.zwisler@...ux.intel.com>