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rcu: Add READ_ONCE() to rcu_data ->gpwrap
The rcu_data structure's ->gpwrap field is read locklessly, and so this commit adds the required READ_ONCE() to a pair of laods in order to avoid destructive compiler optimizations. This data race was reported by KCSAN. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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parent
65bb0dc437
commit
a5b8950180
2 changed files with 2 additions and 2 deletions
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@ -1322,7 +1322,7 @@ static void rcu_accelerate_cbs_unlocked(struct rcu_node *rnp,
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rcu_lockdep_assert_cblist_protected(rdp);
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c = rcu_seq_snap(&rcu_state.gp_seq);
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if (!rdp->gpwrap && ULONG_CMP_GE(rdp->gp_seq_needed, c)) {
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if (!READ_ONCE(rdp->gpwrap) && ULONG_CMP_GE(rdp->gp_seq_needed, c)) {
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/* Old request still live, so mark recent callbacks. */
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(void)rcu_segcblist_accelerate(&rdp->cblist, c);
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return;
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@ -602,7 +602,7 @@ void show_rcu_gp_kthreads(void)
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continue;
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for_each_leaf_node_possible_cpu(rnp, cpu) {
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rdp = per_cpu_ptr(&rcu_data, cpu);
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if (rdp->gpwrap ||
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if (READ_ONCE(rdp->gpwrap) ||
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ULONG_CMP_GE(READ_ONCE(rcu_state.gp_seq),
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READ_ONCE(rdp->gp_seq_needed)))
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continue;
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