[ltt-dev] [RELEASE] Userspace RCU 0.3.0

Mathieu Desnoyers mathieu.desnoyers at polymtl.ca
Tue Nov 3 10:02:34 EST 2009

Hi everyone,

I released userspace RCU 0.3.0, which includes a small API change for
the "deferred work" interface. After discussion with Paul, I decided to
drop the support for call_rcu() and only provide defer_rcu(), to make
sure I don't provide an API with the same name as the kernel RCU but
with different arguments and semantic. It will generate the following
linker error if used:

file.c:240: undefined reference to 

Note that defer_rcu() should *not* be used in RCU read-side C.S.,
because it calls synchronize_rcu() if the queue is full. This is a major
distinction from call_rcu(). (note to self: eventually we should add
some self-check code to detect defer_rcu() nested within RCU read-side

I plan to eventually implement a proper call_rcu() within the userspace
RCU library. It's not, however, a short-term need for me at the moment.



Mathieu Desnoyers
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