maybe dumb question about RCU

[Jeff Haran]

-----Original Message-----
From: Mandeep Sandhu [mailto:mandeepsandhu.chd at gmail.com] 
Sent: Thursday, April 09, 2015 5:21 PM
To: Jeff Haran
Cc: kernelnewbies
Subject: Re: maybe dumb question about RCU

>
> 256         If you are going to be fetching multiple fields from the
> 257         RCU-protected structure, using the local variable is of
> 258         course preferred.  Repeated rcu_dereference() calls look
> 259         ugly and incur unnecessary overhead on Alpha CPUs.
>
> "look ugly and incur unnecessary overhead on Alpha CPUs" is a long way from "can return different pointer values", which is what it should say.

>I agree, that statement is not only misleading, but incorrect too.
>Maybe we can delete it and update it with a "Note:" about your findings? How about sending a doc patch for it?

I can try. Posting patches unmolested through my employer's Outlook email servers has been fraught with frustration in the past when I've tried it. 8^(

But it would be nice to hear from an RCU expert whether this is a feature or a bug. I suspect the former, I really can't see how it could work otherwise, but what do I know?

Jeff Haran