Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1208111

Re: [PATCH v2 7/7] pmem, dax: have direct_access use __pmem annotation

Show all headers | View raw

On Sat, Aug 15, 2015 at 2:19 AM, Christoph Hellwig <hch@lst.de> wrote:
> On Thu, Aug 13, 2015 at 10:51:11AM -0600, Ross Zwisler wrote:
>> Update the annotation for the kaddr pointer returned by direct_access()
>> so that it is a __pmem pointer.  This is consistent with the PMEM driver
>> and with how this direct_access() pointer is used in the DAX code.
>
> IFF we stick to the __pmem annotations this looks good.
>
> That beeing said I start to really dislike them.  We don't special
> accesors to read/write from pmem, we just need to explicitly commit
> it if we want to make it persistent.  So I really don't see the need
> to treat it special and require all the force casts to and from the
> attribute.

I'm not going to put up much of a fight if it's really getting in the way....

That said, while we don't need special accessors we do need guarantees
that anything that has written to a persistent memory address has done
so in a way that wmb_pmem() is able to flush it.  It's more of a "I've
audited this code path for wmb_pmem() compatibility so use this api to
write to pmem."

Perhaps a better way to statically check for missed flushes might be
to have acquire_pmem_for_write() + release() annotations and the final
release does a wmb_pmem(), but as far as I can tell the sparse
acquire/release annotations don't stack.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH v2 7/7] pmem, dax: have direct_access use __pmem annotation Ross Zwisler <ross.zwisler@linux.intel.com> - 2015-08-13 19:00 +0200
  Re: [PATCH v2 7/7] pmem, dax: have direct_access use __pmem annotation Dan Williams <dan.j.williams@intel.com> - 2015-08-13 23:30 +0200
    Re: [PATCH v2 7/7] pmem, dax: have direct_access use __pmem  annotation Ross Zwisler <ross.zwisler@linux.intel.com> - 2015-08-14 19:00 +0200
      Re: [PATCH v2 7/7] pmem, dax: have direct_access use __pmem annotation Dan Williams <dan.j.williams@intel.com> - 2015-08-14 19:00 +0200
        Re: [PATCH v2 7/7] pmem, dax: have direct_access use __pmem  annotation Christoph Hellwig <hch@lst.de> - 2015-08-15 11:20 +0200
          Re: [PATCH v2 7/7] pmem, dax: have direct_access use __pmem annotation Dan Williams <dan.j.williams@intel.com> - 2015-08-15 17:50 +0200
  Re: [PATCH v2 7/7] pmem, dax: have direct_access use __pmem  annotation Christoph Hellwig <hch@lst.de> - 2015-08-15 11:30 +0200
    Re: [PATCH v2 7/7] pmem, dax: have direct_access use __pmem annotation Dan Williams <dan.j.williams@intel.com> - 2015-08-15 17:50 +0200
      Re: [PATCH v2 7/7] pmem, dax: have direct_access use __pmem  annotation Christoph Hellwig <hch@lst.de> - 2015-08-15 18:10 +0200
        Re: [PATCH v2 7/7] pmem, dax: have direct_access use __pmem annotation Dan Williams <dan.j.williams@intel.com> - 2015-08-15 20:10 +0200
      Re: [PATCH v2 7/7] pmem, dax: have direct_access use __pmem  annotation Ross Zwisler <ross.zwisler@linux.intel.com> - 2015-08-17 22:10 +0200

csiph-web