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srcu: Fix process_srcu()/srcu_batches_completed() datarace

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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 <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney 2019-12-22 19:39:35 -08:00
parent 8c9e0cb323
commit 39f91504a0
1 changed files with 1 additions and 1 deletions
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2
kernel/rcu/srcutree.c
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@ -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);