From add0d37b4f1e77de7d170ece43c8d765572a1eab Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 26 Mar 2019 10:22:22 -0700 Subject: 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 --- kernel/rcu/tree_exp.h | 2 +- kernel/rcu/tree_plugin.h | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel/rcu') 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 { -- cgit v1.2.3