Messages in this thread | | | Date | Mon, 27 Feb 2017 20:26:01 +0200 | From | "Michael S. Tsirkin" <> | Subject | Re: [PATCH] hlist_add_tail_rcu disable sparse warning |
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On Fri, Feb 10, 2017 at 07:39:49PM +0200, Michael S. Tsirkin wrote: > sparse is unhappy about this code in hlist_add_tail_rcu: > > struct hlist_node *i, *last = NULL; > > for (i = hlist_first_rcu(h); i; i = hlist_next_rcu(i)) > last = i; > > This is because hlist_next_rcu and hlist_next_rcu return > __rcu pointers. > > It's a false positive - it's a write side primitive and so > does not need to be called in a read side critical section. > > The following trivial patch disables the warning > without changing the behaviour in any way. > > Note: __hlist_for_each_rcu would also remove the warning but it would be > confusing since it calls rcu_derefence and is designed to run in the rcu > read side critical section. > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > ---
ping
> changes since RFC > added commit log text to explain why don't we use __hlist_for_each_rcu > > include/linux/rculist.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/rculist.h b/include/linux/rculist.h > index 4f7a956..bf578e8 100644 > --- a/include/linux/rculist.h > +++ b/include/linux/rculist.h > @@ -509,7 +509,7 @@ static inline void hlist_add_tail_rcu(struct hlist_node *n, > { > struct hlist_node *i, *last = NULL; > > - for (i = hlist_first_rcu(h); i; i = hlist_next_rcu(i)) > + for (i = h->first; i; i = i->next) > last = i; > > if (last) { > -- > MST
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