diff options
| author | Paul E. McKenney <paulmck@kernel.org> | 2020-01-03 15:44:23 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2020-02-20 15:58:22 -0800 |
| commit | 105abf82b0a62664edabcd4c5b4d9414c74ef399 (patch) | |
| tree | cb1adde397babb2e7c1b810f8380a204798d29de /kernel/rcu | |
| parent | 2906d2154cd6ad6e4452cc25315d3cea7bb7f2d7 (diff) | |
rcu: Add WRITE_ONCE() to rcu_node ->qsmaskinitnext
The rcu_state structure's ->qsmaskinitnext field is read locklessly,
so this commit adds the WRITE_ONCE() to an update in order to provide
proper documentation and READ_ONCE()/WRITE_ONCE() pairing.
This data race was reported by KCSAN. Not appropriate for backporting
due to failure being unlikely for systems not doing incessant CPU-hotplug
operations.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 944390981aed..346321aa3c90 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3379,7 +3379,7 @@ void rcu_cpu_starting(unsigned int cpu) rnp = rdp->mynode; mask = rdp->grpmask; raw_spin_lock_irqsave_rcu_node(rnp, flags); - rnp->qsmaskinitnext |= mask; + WRITE_ONCE(rnp->qsmaskinitnext, rnp->qsmaskinitnext | mask); oldmask = rnp->expmaskinitnext; rnp->expmaskinitnext |= mask; oldmask ^= rnp->expmaskinitnext; @@ -3432,7 +3432,7 @@ void rcu_report_dead(unsigned int cpu) rcu_report_qs_rnp(mask, rnp, rnp->gp_seq, flags); raw_spin_lock_irqsave_rcu_node(rnp, flags); } - rnp->qsmaskinitnext &= ~mask; + WRITE_ONCE(rnp->qsmaskinitnext, rnp->qsmaskinitnext & ~mask); raw_spin_unlock_irqrestore_rcu_node(rnp, flags); raw_spin_unlock(&rcu_state.ofl_lock); |