Messages in this thread | | | Date | Thu, 12 Oct 2017 11:24:54 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH 2/3] srcu: queue work without holding the lock |
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On Thu, Oct 12, 2017 at 10:53:35AM +0200, Sebastian Andrzej Siewior wrote: > On 2017-10-10 14:43:13 [-0700], Paul E. McKenney wrote: > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > > index 6d5880089ff6..558f9e7b283e 100644 > > --- a/kernel/rcu/srcutree.c > > +++ b/kernel/rcu/srcutree.c > > @@ -830,7 +866,7 @@ void __call_srcu(struct srcu_struct *sp, struct rcu_head *rhp, > > rhp->func = func; > > local_irq_save(flags); > > sdp = this_cpu_ptr(sp->sda); > > - raw_spin_lock_rcu_node(sdp); > > + spin_lock_rcu_node(sdp); > > This and the same thing in srcu_might_be_idle() does not work because > local_irq_save() + spin_lock() != spin_lock_irqsave() > but > local_irq_save() + raw_spinlock = raw_spin_lock_irqsave() > > I think that preempt_disable() for a stable this_cpu_ptr() is enough > here. I replaced local_irq_save() with local_lock_irqsave() on RT which > provides a per-CPU spinlock (for mutual exclusion) and disables > interrupts in !RT mode. > > I've been testing this for a while and it seems to work. Thank you.
So I keep mainline as is, and the local_irq_save()-to-local_lock_irqsave() conversion happens in -rt, given that mainline doesn't have a local_lock_irqsave(), correct?
And just so you know, there is one patchset adding call_srcu() that I am following up on. Looks to me like it is OK with this change, but if not, well, back to the drawing board... :-/
Thanx, Paul
> > rcu_segcblist_enqueue(&sdp->srcu_cblist, rhp, false); > > rcu_segcblist_advance(&sdp->srcu_cblist, > > rcu_seq_current(&sp->srcu_gp_seq)); > > > Sebastian >
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