From 39f91504a03a7a2abdb52205106942fa4a548d0d Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 22 Dec 2019 19:39:35 -0800 Subject: srcu: Fix process_srcu()/srcu_batches_completed() datarace The srcu_struct structure's ->srcu_idx field is accessed locklessly, so reads must use READ_ONCE(). This commit therefore adds the needed READ_ONCE() invocation where it was missed. This data race was reported by KCSAN. Not appropriate for backporting due to failure being unlikely. Signed-off-by: Paul E. McKenney --- kernel/rcu/srcutree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 79848f7d575d..119a37319e67 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -1079,7 +1079,7 @@ EXPORT_SYMBOL_GPL(srcu_barrier); */ unsigned long srcu_batches_completed(struct srcu_struct *ssp) { - return ssp->srcu_idx; + return READ_ONCE(ssp->srcu_idx); } EXPORT_SYMBOL_GPL(srcu_batches_completed); -- cgit v1.2.3