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| author | Paul E. McKenney <paulmck@kernel.org> | 2019-12-21 21:41:48 +0300 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2020-02-21 03:03:31 +0300 |
| commit | 202489101f2e6cee3f6dffc087a4abd5fdfcebda (patch) | |
| tree | cedef3be1fb42eb8f0a08d7e1652ec998bd9a4ed /kernel/rcu | |
| parent | beabc806f5aaa158fc90a939215e8b44ee9d7acc (diff) | |
| download | linux-202489101f2e6cee3f6dffc087a4abd5fdfcebda.tar.xz | |
rcutorture: Fix rcu_torture_one_read()/rcu_torture_writer() data race
The ->rtort_pipe_count field in the rcu_torture structure checks for
too-short grace periods, and is therefore read by rcutorture's readers
while being updated by rcutorture's writers. This commit therefore
adds the needed READ_ONCE() and WRITE_ONCE() invocations.
This data race was reported by KCSAN. Not appropriate for backporting
due to failure being unlikely and due to this being rcutorture.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/rcutorture.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 5efd9503df56..edd97465a0f7 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -375,11 +375,12 @@ rcu_torture_pipe_update_one(struct rcu_torture *rp) { int i; - i = rp->rtort_pipe_count; + i = READ_ONCE(rp->rtort_pipe_count); if (i > RCU_TORTURE_PIPE_LEN) i = RCU_TORTURE_PIPE_LEN; atomic_inc(&rcu_torture_wcount[i]); - if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) { + WRITE_ONCE(rp->rtort_pipe_count, i + 1); + if (rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) { rp->rtort_mbtest = 0; return true; } @@ -1015,7 +1016,8 @@ rcu_torture_writer(void *arg) if (i > RCU_TORTURE_PIPE_LEN) i = RCU_TORTURE_PIPE_LEN; atomic_inc(&rcu_torture_wcount[i]); - old_rp->rtort_pipe_count++; + WRITE_ONCE(old_rp->rtort_pipe_count, + old_rp->rtort_pipe_count + 1); switch (synctype[torture_random(&rand) % nsynctypes]) { case RTWS_DEF_FREE: rcu_torture_writer_state = RTWS_DEF_FREE; @@ -1291,7 +1293,7 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp) atomic_inc(&n_rcu_torture_mberror); rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp); preempt_disable(); - pipe_count = p->rtort_pipe_count; + pipe_count = READ_ONCE(p->rtort_pipe_count); if (pipe_count > RCU_TORTURE_PIPE_LEN) { /* Should not happen, but... */ pipe_count = RCU_TORTURE_PIPE_LEN; |