linux-kernel - Re: [PATCH v3 08/14] x86, dax, libnvdimm: move wb_cache

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Date:   Sun, 18 Jun 2017 19:06:14 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Christoph Hellwig <hch@....de>
Cc:     "linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
        Jan Kara <jack@...e.cz>, dm-devel@...hat.com,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        X86 ML <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jeff Moyer <jmoyer@...hat.com>, Ingo Molnar <mingo@...hat.com>,
        "Oliver O'Halloran" <oohall@...il.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        "H. Peter Anvin" <hpa@...or.com>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>
Subject: Re: [PATCH v3 08/14] x86, dax, libnvdimm: move wb_cache_pmem() to libnvdimm

On Sun, Jun 18, 2017 at 1:40 AM, Christoph Hellwig <hch@....de> wrote:
>> +void clean_cache_range(void *addr, size_t size);
>>
>>  static inline int
>>  __copy_from_user_inatomic_nocache(void *dst, const void __user *src,
>> diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
>> index f42d2fd86ca3..baa80ff29da8 100644
>> --- a/arch/x86/lib/usercopy_64.c
>> +++ b/arch/x86/lib/usercopy_64.c
>> @@ -85,7 +85,7 @@ copy_user_handle_tail(char *to, char *from, unsigned len)
>>   * instruction. Note that @size is internally rounded up to be cache
>>   * line size aligned.
>>   */
>> -static void clean_cache_range(void *addr, size_t size)
>> +void clean_cache_range(void *addr, size_t size)
>
> Can you keep clean_cache_range private please?  Just add
> arch_wb_cache_pmem to usercopy_64.c just behind it so that the
> compiler can tail-call and export that instead.
>
>> --- a/drivers/nvdimm/pmem.h
>> +++ b/drivers/nvdimm/pmem.h
>> @@ -4,6 +4,13 @@
>>  #include <linux/types.h>
>>  #include <linux/pfn_t.h>
>>  #include <linux/fs.h>
>> +#include <asm/pmem.h>
>> +
>> +#ifndef CONFIG_ARCH_HAS_PMEM_API
>> +static inline void arch_wb_cache_pmem(void *addr, size_t size)
>> +{
>> +}
>> +#endif
>
> And our normal Linux style would be to have this linux linux/pmem.h,
> which should always be included for the asm version.

Ok, will do.