On Wed, Oct 07, 2015 at 02:46:56PM +0100, Srinivas Kandagatla wrote:

On 07/10/15 12:33, Russell King - ARM Linux wrote:

quoted

On Wed, Oct 07, 2015 at 12:00:47PM +0100, Srinivas Kandagatla wrote:

quoted

As required by many providers like at24/at25/mxs-ocotp/qfprom and may be
other providers would want to allow root-only to read the nvmem content.
So making the defaults to be root-only access would address the request
and also provide flexibility to providers to specify there own permissions
on top of the root-only using the perm flag in nvmem_config.
Making this dynamic did cut down lot of static binary attributes in the
code.

Check what the lifetime of a struct bin_attribute is before you embed it
into any other structure.  Sorry, but I think you're going to have to

Lifetime of the "static struct bin_attribute bin_attr_template" is static
and a memcpy of which is made into nvmem->bin whose lifetime is till the
nvmem_release() which happens at device_release(), so there should be no
issue in using a copy of bin_attribute.

You're assuming that code doesn't touch the attribute after releasing
the last refcount on the device... unless you've actually checked
that, the code is unsafe.

I'm not saying it does or it doesn't (I don't know) but unless you
actually have checked, you haven't done sufficient homework prior to
sending this patch.

Just remember for next time you want to do something similar to this.

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