Re: [PATCH tip/core/rcu 2/3] rcu: make hot-unplugged CPU relinquish its own RCU callbacks

Steven Rostedt
2009-10-07T13:18:13Z

Paul,

Still suffering jetlag? ;-)

On Tue, 2009-10-06 at 21:48 -0700, Paul E. McKenney wrote:
> From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
>
> The current interaction between RCU and CPU hotplug requires that
> RCU block in CPU notifiers waiting for callbacks to drain. This can
> be greatly simplified by haing each CPU relinquish its own callbacks,
having

> and for both _rcu_barrier() and CPU_DEAD notifiers to adopt all callbacks
> that were previously relinquished. This change also eliminates the
> possibility of certain types of hangs due to the previous practice of
> waiting for callbacks to be invoked from within CPU notifiers. If you
> don't every wait, you cannot hang.
ever

;-)

>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

-- Steve