On Tue, Jun 19, 2018 at 02:32:11PM +0200, Loic Poulain wrote:
> Hi Johan, Srini,
> 
> On 18 June 2018 at 11:47, Srinivas Kandagatla
> <srinivas.kandaga...@linaro.org> wrote:
> > On 18/06/18 09:46, Johan Hovold wrote:

> >> I'm not necessarily against the idea, but nvmem core needs to be fixed
> >> so that it can handle hotplugging before this can be considered for
> >> merging.
> >>
> >> Right now it just returns -EBUSY from nvmem_unregister(), which results
> >> in all kinds of memory leaks, use-after-frees and crashes when user
> >> space holds the character device open while the device is being
> >> unplugged.
> 
> Correct me if I'm wrong, but nvmem is just exposed to userspace as a
> simple sysfs device attribute (nvmem), removing a device and its attribute(s)
> dynamically is well managed by sysfs, even if userspace has file open.

My bad, I misremembered what interface nvmem was using and only saw the 
deregistration refusal in nvmem_unregister() during a quick check.

> The only risk here is when a kernel internal consumer still has a reference to
> the nvmem device on removal, which is not the case in our context.

Right.

> > I can also suggest you to try devm_nvmem_register().
> 
> Yes, I'm going to send a v2.

I'll take a closer look soonish too.

Johan
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