Messages in this thread | | | Date | Wed, 26 Apr 2017 09:13:43 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH] hlist_add_tail_rcu disable sparse warning |
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Paul,
Did you see this email?
-- Steve
On Mon, 27 Feb 2017 20:26:01 +0200 "Michael S. Tsirkin" <mst@redhat.com> wrote:
> 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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