preempt_disable_notrace();
rdp = this_cpu_ptr(&rcu_data);
rnp = rdp->mynode;
- if (rdp->grpmask & rcu_rnp_online_cpus(rnp))
+ if (rdp->grpmask & rcu_rnp_online_cpus(rnp) || READ_ONCE(rnp->ofl_seq) & 0x1)
ret = true;
preempt_enable_notrace();
return ret;
*/
static bool rcu_gp_init(void)
{
+ unsigned long firstseq;
unsigned long flags;
unsigned long oldmask;
unsigned long mask;
*/
rcu_state.gp_state = RCU_GP_ONOFF;
rcu_for_each_leaf_node(rnp) {
+ smp_mb(); // Pair with barriers used when updating ->ofl_seq to odd values.
+ firstseq = READ_ONCE(rnp->ofl_seq);
+ if (firstseq & 0x1)
+ while (firstseq == READ_ONCE(rnp->ofl_seq))
+ schedule_timeout_idle(1); // Can't wake unless RCU is watching.
+ smp_mb(); // Pair with barriers used when updating ->ofl_seq to even values.
raw_spin_lock(&rcu_state.ofl_lock);
raw_spin_lock_irq_rcu_node(rnp);
if (rnp->qsmaskinit == rnp->qsmaskinitnext &&
rnp = rdp->mynode;
mask = rdp->grpmask;
+ WRITE_ONCE(rnp->ofl_seq, rnp->ofl_seq + 1);
+ WARN_ON_ONCE(!(rnp->ofl_seq & 0x1));
+ smp_mb(); // Pair with rcu_gp_cleanup()'s ->ofl_seq barrier().
raw_spin_lock_irqsave_rcu_node(rnp, flags);
WRITE_ONCE(rnp->qsmaskinitnext, rnp->qsmaskinitnext | mask);
newcpu = !(rnp->expmaskinitnext & mask);
} else {
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
+ smp_mb(); // Pair with rcu_gp_cleanup()'s ->ofl_seq barrier().
+ WRITE_ONCE(rnp->ofl_seq, rnp->ofl_seq + 1);
+ WARN_ON_ONCE(rnp->ofl_seq & 0x1);
smp_mb(); /* Ensure RCU read-side usage follows above initialization. */
}
/* Remove outgoing CPU from mask in the leaf rcu_node structure. */
mask = rdp->grpmask;
+ WRITE_ONCE(rnp->ofl_seq, rnp->ofl_seq + 1);
+ WARN_ON_ONCE(!(rnp->ofl_seq & 0x1));
+ smp_mb(); // Pair with rcu_gp_cleanup()'s ->ofl_seq barrier().
raw_spin_lock(&rcu_state.ofl_lock);
raw_spin_lock_irqsave_rcu_node(rnp, flags); /* Enforce GP memory-order guarantee. */
rdp->rcu_ofl_gp_seq = READ_ONCE(rcu_state.gp_seq);
WRITE_ONCE(rnp->qsmaskinitnext, rnp->qsmaskinitnext & ~mask);
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
raw_spin_unlock(&rcu_state.ofl_lock);
+ smp_mb(); // Pair with rcu_gp_cleanup()'s ->ofl_seq barrier().
+ WRITE_ONCE(rnp->ofl_seq, rnp->ofl_seq + 1);
+ WARN_ON_ONCE(rnp->ofl_seq & 0x1);
rdp->cpu_started = false;
}