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| author | Paul E. McKenney <paulmck@kernel.org> | 2020-01-03 15:22:01 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2020-04-27 11:01:16 -0700 |
| commit | 065a6db12a80fac4eccc37e6bef14b0f4a610f31 (patch) | |
| tree | 8fcb9c6a2f1586bbf45be1e8bfbd86a82ebdd3f1 /kernel/rcu | |
| parent | 314eeb43e5f22856b281c91c966e51e5782a3498 (diff) | |
| download | linux-next-065a6db12a80fac4eccc37e6bef14b0f4a610f31.tar.gz | |
rcu: Add READ_ONCE and data_race() to rcu_node ->boost_tasks
The rcu_node structure's ->boost_tasks field is read locklessly, so this
commit adds the READ_ONCE() to one load in order to avoid destructive
compiler optimizations. The other load is from a diagnostic print,
so data_race() suffices.
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>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 35d77db035bd..ed6bb460c7c6 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -760,7 +760,7 @@ dump_blkd_tasks(struct rcu_node *rnp, int ncheck) pr_info("%s: %d:%d ->qsmask %#lx ->qsmaskinit %#lx ->qsmaskinitnext %#lx\n", __func__, rnp1->grplo, rnp1->grphi, rnp1->qsmask, rnp1->qsmaskinit, rnp1->qsmaskinitnext); pr_info("%s: ->gp_tasks %p ->boost_tasks %p ->exp_tasks %p\n", - __func__, READ_ONCE(rnp->gp_tasks), rnp->boost_tasks, + __func__, READ_ONCE(rnp->gp_tasks), data_race(rnp->boost_tasks), READ_ONCE(rnp->exp_tasks)); pr_info("%s: ->blkd_tasks", __func__); i = 0; @@ -1036,7 +1036,8 @@ static int rcu_boost_kthread(void *arg) for (;;) { WRITE_ONCE(rnp->boost_kthread_status, RCU_KTHREAD_WAITING); trace_rcu_utilization(TPS("End boost kthread@rcu_wait")); - rcu_wait(rnp->boost_tasks || READ_ONCE(rnp->exp_tasks)); + rcu_wait(READ_ONCE(rnp->boost_tasks) || + READ_ONCE(rnp->exp_tasks)); trace_rcu_utilization(TPS("Start boost kthread@rcu_wait")); WRITE_ONCE(rnp->boost_kthread_status, RCU_KTHREAD_RUNNING); more2boost = rcu_boost(rnp); |