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Re: [RFC/PATCH] replace preempt_* calls with rcu_read_* variants


On Tue, Mar 14, 2006 at 05:44:15AM -0800, Ananth N Mavinakayanahalli wrote:
> 
>    Hi,
> 
>    Can    somebody    please   remind   me   why   we   are   not   using
>    rcu_read_unlock/lock()
>    to RCU protect the kprobe handlers, instead, are using
>    preempt_disable/enable()?

"In some realtime-friendly RCU implementations, the RCU read-side critical
sections do not disable preemption. So, if you are using synchronize_sched()
on the update side, you need to use preempt_disable() (or some other
primitive that disables preemption, for example, any of the primitives
that disables hardware interrupts) on the read side."

http://www.ussg.iu.edu/hypermail/linux/kernel/0510.2/0537.html

-thanks,
-Anil


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