Re: Question about the barrier() in hlist_nulls_for_each_entry_rcu()

[Eric Dumazet]

On Thu, Jul 20, 2023 at 8:54 PM Alan Huang <mmpgouride@xxxxxxxxx> wrote:
>
> Hi,
>
> I noticed a commit c87a124a5d5e(“net: force a reload of first item in hlist_nulls_for_each_entry_rcu”)
> and a related discussion [1].
>
> After reading the whole discussion, it seems like that ptr->field was cached by gcc even with the deprecated
> ACCESS_ONCE(), so my question is:
>
>         Is that a compiler bug? If so, has this bug been fixed today, ten years later?
>
>         What about READ_ONCE(ptr->field)?

Make sure sparse is happy.

Do you have a patch for review ?


>
>
> [1] https://lore.kernel.org/all/1369699930.3301.494.camel@edumazet-glaptop/
>
> Thanks,
> Alan