[PATCH v3] power: introduce library for device-specific OPPs

Nishanth Menon [off-list ref] writes:

Rafael J. Wysocki had written, on 09/22/2010 07:03 PM, the following:

quoted

[Trimming the CC list slightly.]

[...]

quoted

...

First, thanks for addressing the previous comments, things look much better
now.  In particular the documentation has been improved a lot in my view.

Thanks for the excellent reviews :)

[...]

quoted

quoted

+
+WARNING on OPP List Modification Vs Query operations:
+----------------------------------------------------
+The OPP layer's query functions are expected to be used in multiple contexts
+(including calls from interrupt locked context) based on SoC framework
+implementation. Only OPP modification functions are guaranteed exclusivity by
+the OPP library. Exclusivity between query functions and modification functions
+should be handled by the users such as the SoC framework appropriately; else,
+there is a risk for the query functions to retrieve stale data.

Well, this sounds like a good use case for RCU.

Kevin did point out rwlock but am I confusing with
http://lwn.net/Articles/364583/
If I get the message right, rwlock is more or less on it's way out?

RCU is different from the reader-writer locks that are on their way out.

Let's think about RCU a little more and see if it might be worth using.

As these APIs are infrequencly accessed, I'm thinking a single spinlock
to protect the whole list from concurrent access/modification is
sufficient.

Kevin