Commit-ID: add0d37b4f1e77de7d170ece43c8d765572a1eab
Gitweb: https://git.kernel.org/tip/add0d37b4f1e77de7d170ece43c8d765572a1eab
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxx>
AuthorDate: Tue, 26 Mar 2019 10:22:22 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxx>
CommitDate: Tue, 26 Mar 2019 14:38:38 -0700
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@xxxxxxxxxxxxx>
---
kernel/rcu/tree_exp.h | 2 +-
kernel/rcu/tree_plugin.h | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index ec4fb93a5dbe..1ee0782213b8 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;
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 81d3cd821891..6ddb3c05e88f 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -285,7 +285,7 @@ static void rcu_qs(void)
TPS("cpuqs"));
__this_cpu_write(rcu_data.cpu_no_qs.b.norm, false);
barrier(); /* Coordinate with rcu_flavor_sched_clock_irq(). */
- current->rcu_read_unlock_special.b.need_qs = false;
+ WRITE_ONCE(current->rcu_read_unlock_special.b.need_qs, false);
}
}
@@ -817,7 +817,7 @@ void exit_rcu(void)
if (unlikely(!list_empty(¤t->rcu_node_entry))) {
t->rcu_read_lock_nesting = 1;
barrier();
- t->rcu_read_unlock_special.b.blocked = true;
+ WRITE_ONCE(t->rcu_read_unlock_special.b.blocked, true);
} else if (unlikely(t->rcu_read_lock_nesting)) {
t->rcu_read_lock_nesting = 1;
} else {
|