Re: [PATCH 1/1] rcu/sync: remove un-used rcu_sync_enter_start function

[Oleg Nesterov]

On 01/16, Paul E. McKenney wrote:
>
> On Thu, Jan 11, 2024 at 02:57:22PM +0530, Onkarnarth wrote:
> > From: Onkarnath <onkarnath.1@xxxxxxxxxxx>
> >
> > With commit '6a010a49b63a ("cgroup: Make !percpu threadgroup_rwsem
> > operations optional")' usage of rcu_sync_enter_start is removed.
> >
> > So this function can also be removed.
> >
> > Signed-off-by: Onkarnath <onkarnath.1@xxxxxxxxxxx>
> > Signed-off-by: Maninder Singh <maninder1.s@xxxxxxxxxxx>

Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>



For the record, this was already discussed, see
https://lore.kernel.org/all/20220725121208.GB28662@xxxxxxxxxx/

Note also the patch in this message, __rcu_sync_enter(wait => false)
is a better alternative if someone needs rcu_sync_enter_start() again.

This patch probably makes sense anyway. Not only cgroup_favor_dynmods()
can use __rcu_sync_enter(), freeze_super() can use it too to avoid
3 synchronize_rcu()'s in a row.

Oleg.