diff options
| author | Paul E. McKenney <paulmck@kernel.org> | 2020-01-03 14:53:31 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2020-02-20 15:58:22 -0800 |
| commit | 0937d045732b5dd5e5df1fb6355d5f4e01f3c4d7 (patch) | |
| tree | 679da8876a4e372ab67634dd2f3b1b675c7b6a8f /kernel/rcu | |
| parent | b0c18c87730a4de6da0303fa99aea43e814233f9 (diff) | |
rcu: Add READ_ONCE() to rcu_node ->gp_seq
The rcu_node structure's ->gp_seq field is read locklessly, so this
commit adds the READ_ONCE() to several loads in order to avoid
destructive compiler optimizations.
This data race was reported by KCSAN. Not appropriate for backporting
because this affects only tracing and warnings.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index bb57c24dbe9a..236692d7762f 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1126,8 +1126,9 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) static void trace_rcu_this_gp(struct rcu_node *rnp, struct rcu_data *rdp, unsigned long gp_seq_req, const char *s) { - trace_rcu_future_grace_period(rcu_state.name, rnp->gp_seq, gp_seq_req, - rnp->level, rnp->grplo, rnp->grphi, s); + trace_rcu_future_grace_period(rcu_state.name, READ_ONCE(rnp->gp_seq), + gp_seq_req, rnp->level, + rnp->grplo, rnp->grphi, s); } /* @@ -1904,7 +1905,7 @@ static void rcu_report_qs_rnp(unsigned long mask, struct rcu_node *rnp, rnp_c = rnp; rnp = rnp->parent; raw_spin_lock_irqsave_rcu_node(rnp, flags); - oldmask = rnp_c->qsmask; + oldmask = READ_ONCE(rnp_c->qsmask); } /* @@ -2052,7 +2053,7 @@ int rcutree_dying_cpu(unsigned int cpu) return 0; blkd = !!(rnp->qsmask & rdp->grpmask); - trace_rcu_grace_period(rcu_state.name, rnp->gp_seq, + trace_rcu_grace_period(rcu_state.name, READ_ONCE(rnp->gp_seq), blkd ? TPS("cpuofl") : TPS("cpuofl-bgp")); return 0; } |