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SubjectRe: [PATCH] rcu: Use the proper lockdep annotation in dump_blkd_tasks()
On Fri, Mar 09, 2018 at 09:32:18AM +0800, Boqun Feng wrote:
> Sparse reported this:
>
> | kernel/rcu/tree_plugin.h:814:9: warning: incorrect type in argument 1 (different modifiers)
> | kernel/rcu/tree_plugin.h:814:9: expected struct lockdep_map const *lock
> | kernel/rcu/tree_plugin.h:814:9: got struct lockdep_map [noderef] *<noident>
>
> This is caused by using vanilla lockdep annotations on rcu_node::lock,
> and that requires accessing ->lock of rcu_node directly. However we need
> to keep rcu_node::lock __private to avoid breaking its extra ordering
> guarantee. And we have a dedicated lockdep annotation for
> rcu_node::lock, so use it.
>
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>

Good eyes! Queued both this and v3 for testing and further review.

Thanx, Paul

> ---
> kernel/rcu/tree_plugin.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
> index 9accacffd138..ea33f57abae5 100644
> --- a/kernel/rcu/tree_plugin.h
> +++ b/kernel/rcu/tree_plugin.h
> @@ -811,7 +811,7 @@ static void dump_blkd_tasks(struct rcu_node *rnp, int ncheck)
> int i;
> struct list_head *lhp;
>
> - lockdep_assert_held(&rnp->lock);
> + raw_lockdep_assert_held_rcu_node(rnp);
> pr_info("%s: grp: %d-%d level: %d ->qamask %#lx ->gp_tasks %p ->boost_tasks %p ->exp_tasks %p &->blkd_tasks: %p offset: %u\n", __func__, rnp->grplo, rnp->grphi, rnp->level, rnp->qsmask, rnp->gp_tasks, rnp->boost_tasks, rnp->exp_tasks, &rnp->blkd_tasks, (unsigned int)offsetof(typeof(*rnp), blkd_tasks));
> pr_cont("\t->blkd_tasks");
> i = 0;
> --
> 2.16.2
>

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