rcu: Correct READ_ONCE()/WRITE_ONCE() for ->rcu_read_unlock_special
The task_struct structure's ->rcu_read_unlock_special field is only ever
read or written by the owning task, but it is accessed both at process
and interrupt levels. It may therefore be accessed using plain reads
and writes while interrupts are disabled, but must be accessed using
READ_ONCE() and WRITE_ONCE() or better otherwise. This commit makes a
few adjustments to align with this discipline.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index ec4fb93..1ee0782 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -633,7 +633,7 @@ static void rcu_exp_handler(void *unused)
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (rnp->expmask & rdp->grpmask) {
rdp->deferred_qs = true;
- WRITE_ONCE(t->rcu_read_unlock_special.b.exp_hint, true);
+ t->rcu_read_unlock_special.b.exp_hint = true;
}
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
return;