Re: [PATCH v2 13/14] RDMA/rxe: Rename kfree_rcu() to kvfree_rcu_mightsleep()

[Joel Fernandes]

On Wed, Mar 15, 2023 at 2:38 PM Bob Pearson <rpearsonhpe@xxxxxxxxx> wrote:
>
> On 3/15/23 13:19, Joel Fernandes (Google) wrote:
> > The k[v]free_rcu() macro's single-argument form is deprecated.
> > Therefore switch to the new k[v]free_rcu_mightsleep() variant. The goal
> > is to avoid accidental use of the single-argument forms, which can
> > introduce functionality bugs in atomic contexts and latency bugs in
> > non-atomic contexts.
> >
> > There is no functionality change with this patch.
> >
> > Link: https://lore.kernel.org/rcu/20230201150815.409582-1-urezki@xxxxxxxxx
> > Acked-by: Zhu Yanjun <zyjzyj2000@xxxxxxxxx>
> > Reviewed-by: Bob Pearson <rpearsonhpe@xxxxxxxxx>
> > Reviewed-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> > Fixes: 72a03627443d ("RDMA/rxe: Remove rxe_alloc()")
> > Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
> > ---
> >  drivers/infiniband/sw/rxe/rxe_mr.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c
> > index b10aa1580a64..ae3a100e18fb 100644
> > --- a/drivers/infiniband/sw/rxe/rxe_mr.c
> > +++ b/drivers/infiniband/sw/rxe/rxe_mr.c
> > @@ -731,7 +731,7 @@ int rxe_dereg_mr(struct ib_mr *ibmr, struct ib_udata *udata)
> >               return -EINVAL;
> >
> >       rxe_cleanup(mr);
> > -     kfree_rcu(mr);
> > +     kfree_rcu_mightsleep(mr);
> >       return 0;
> >  }
> >
> Please replace kfree_rcu_mightsleep() by kfree(). There is no need to delay the kfree(mr).

I thought you said either was Ok, but yeah that's fine with me. I was
trying to play it safe ;-). An extra GP may not hurt, but not having
one when it is needed might. I will update it to just be kfree.

<quote>
>   rxe_cleanup(mr);
> - kfree_rcu(mr);
> + kfree_rcu_mightsleep(mr);
>   return 0;
>  }
>

I would prefer just
- kfree_rcu(mr);
+ kfree(mr);

but either one will work.
Bob
</quote>

 - Joel