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authorPaul E. McKenney <paulmck@kernel.org>2020-01-03 11:38:51 -0800
committerPaul E. McKenney <paulmck@kernel.org>2020-02-20 15:58:22 -0800
commit7672d647ddae37d2ea267159950bcc311e962434 (patch)
tree91c4c0ed6bd41b08b32a1146bd5e8dc5d3e7eaa3 /kernel/rcu
parent8a7e8f51714004112a0bbbf751f3dd0fcbbbc983 (diff)
rcu: Add WRITE_ONCE() to rcu_node ->qsmask update
The rcu_node structure's ->qsmask 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. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
-rw-r--r--kernel/rcu/tree.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index d91c9156fab2..bb57c24dbe9a 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1881,7 +1881,7 @@ static void rcu_report_qs_rnp(unsigned long mask, struct rcu_node *rnp,
WARN_ON_ONCE(oldmask); /* Any child must be all zeroed! */
WARN_ON_ONCE(!rcu_is_leaf_node(rnp) &&
rcu_preempt_blocked_readers_cgp(rnp));
- rnp->qsmask &= ~mask;
+ WRITE_ONCE(rnp->qsmask, rnp->qsmask & ~mask);
trace_rcu_quiescent_state_report(rcu_state.name, rnp->gp_seq,
mask, rnp->qsmask, rnp->level,
rnp->grplo, rnp->grphi,