diff options
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index be59a5d7299d..62383ce5161f 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3077,15 +3077,22 @@ static void rcu_barrier_trace(const char *s, int cpu, unsigned long done) /* * RCU callback function for rcu_barrier(). If we are last, wake * up the task executing rcu_barrier(). + * + * Note that the value of rcu_state.barrier_sequence must be captured + * before the atomic_dec_and_test(). Otherwise, if this CPU is not last, + * other CPUs might count the value down to zero before this CPU gets + * around to invoking rcu_barrier_trace(), which might result in bogus + * data from the next instance of rcu_barrier(). */ static void rcu_barrier_callback(struct rcu_head *rhp) { + unsigned long __maybe_unused s = rcu_state.barrier_sequence; + if (atomic_dec_and_test(&rcu_state.barrier_cpu_count)) { - rcu_barrier_trace(TPS("LastCB"), -1, - rcu_state.barrier_sequence); + rcu_barrier_trace(TPS("LastCB"), -1, s); complete(&rcu_state.barrier_completion); } else { - rcu_barrier_trace(TPS("CB"), -1, rcu_state.barrier_sequence); + rcu_barrier_trace(TPS("CB"), -1, s); } } |