On Tue, Apr 30, 2013 at 10:12:38AM +0300, Julian Anastasov wrote:
>
> Hello,
>
> On Tue, 30 Apr 2013, Simon Horman wrote:
>
> > This is intended for use in loops which read data protected by RCU and may
> > have a large number of iterations. Such an example is dumping the list of
> > connections known to IPVS: ip_vs_conn_array() and ip_vs_conn_seq_next().
> >
> > The call to cond_resched() is guarded by #ifndef CONFIG_PREEMPT_RCU as in
> > the case of CONFIG_PREEMPT_RCU _rcu_read_unlock() will check to see if the
> > RCU core needs to be informed, so there is no need to invoke cond_resched()
> > in that case. Thanks to Paul E. McKenney for explaining this.
> >
> > cond_resched_rcu_lock() suggested by Eric Dumazet.
> > ifndef guard suggested by Paul E. McKenney and Julian Anastasov.
> >
> > Cc: Eric Dumazet <[email protected]>
> > Cc: Paul E. McKenney <[email protected]>
> > Cc: Julian Anastasov <[email protected]>
> > Acked-by: Ingo Molnar <[email protected]>
> > Signed-off-by: Simon Horman <[email protected]>
> >
> > ---
> >
> > v2
> > * Add guard the call to cond_resched()
> > ---
> > include/linux/sched.h | 11 +++++++++++
> > 1 file changed, 11 insertions(+)
> >
> > diff --git a/include/linux/sched.h b/include/linux/sched.h
> > index e692a02..66da71c 100644
> > --- a/include/linux/sched.h
> > +++ b/include/linux/sched.h
> > @@ -2787,3 +2787,14 @@ static inline unsigned long rlimit_max(unsigned int
> > limit)
> > }
> >
> > #endif
> > +
> > +static void inline cond_resched_rcu_lock(void)
> > +{
> > + if (need_resched()) {
>
> Ops, it should be without above need_resched.
Thanks, to clarify, just this:
static void inline cond_resched_rcu_lock(void)
{
rcu_read_unlock();
#ifndef CONFIG_PREEMPT_RCU
cond_resched();
#endif
rcu_read_lock();
}
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