Re: Q. hlist_bl_add_head_rcu() in d_alloc_parallel()

[Hekuang <hekuang@huawei.com>]

  在 2016/6/29 16:17, Al Viro 写道:
> On Sat, Jun 25, 2016 at 06:25:58PM -0700, Linus Torvalds wrote:
>> On Sat, Jun 25, 2016 at 3:54 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
>>> BTW, speaking of that area - is there any reason why dentry_cmp()
>>> isn't simply
>>>          return dentry_string_cmp(lockless_dereference(dentry->d_name.name),
>>>                                   ct, tcount);
>>> other than "it predates lockless_dereference()"?
>> No, the only important thing is that it's a read-once, and has the
>> smp_read_barrier_depends().
>>
>> So lockless_derefence() looks like the right thing to do, it is just
>> that - as you suspected - the code predates that concept.
> ... and as the matter of fact, patch to that effect (only cosmetically different
> from what I'd cooked) had been posted by He Kuang back in March.  At least
> I'd spotted that before pushing mine out...
>
> The patch posted back then applied, with slightly edited commit message.  Apologies
> for missing it...
Its okay and really appreciate you remembering, I've forgotten that 
patch if not mentioned. :-)

Thank you.