Re: [PATCH 1/2] list: add hlist_unhashed_lockless()

[Eric Dumazet]

On Fri, Nov 8, 2019 at 11:24 AM Paul E. McKenney <paulmck@xxxxxxxxxx> wrote:
>
> On Thu, Nov 07, 2019 at 11:37:37AM -0800, Eric Dumazet wrote:
> > We would like to use hlist_unhashed() from timer_pending(),
> > which runs without protection of a lock.
> >
> > Note that other callers might also want to use this variant.
> >
> > Instead of forcing a READ_ONCE() for all hlist_unhashed()
> > callers, add a new helper with an explicit _lockless suffix
> > in the name to better document what is going on.
> >
> > Also add various WRITE_ONCE() in __hlist_del(), hlist_add_head()
> > and hlist_add_before()/hlist_add_behind() to pair with
> > the READ_ONCE().
> >
> > Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> > Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>
> I have queued this, but if you prefer it go some other way:
>
> Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
>
> But shouldn't the uses in include/linux/rculist.h also be converted
> into the patch below?  If so, I will squash the following into your
> patch.
>
>                                                 Thanx, Paul
>
> ------------------------------------------------------------------------

Agreed, thanks for the addition of this Paul.