linux-kernel - Re: [PATCH v2 13/14] RDMA/rxe: Rename kfree_rcu() to kvfree_rcu

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAEXW_YTB+LBG+oL02c0JfmAzoGSkZDM=QW1EXKbO3f-g0i4ddA@mail.gmail.com>
Date:   Wed, 15 Mar 2023 14:41:11 -0400
From:   Joel Fernandes <joel@...lfernandes.org>
To:     Bob Pearson <rpearsonhpe@...il.com>
Cc:     Zhu Yanjun <zyjzyj2000@...il.com>, Jason Gunthorpe <jgg@...pe.ca>,
        Leon Romanovsky <leon@...nel.org>,
        Devesh Sharma <devesh.s.sharma@...cle.com>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Zhu Yanjun <yanjun.zhu@...ux.dev>, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 13/14] RDMA/rxe: Rename kfree_rcu() to kvfree_rcu_mightsleep()

On Wed, Mar 15, 2023 at 2:38 PM Bob Pearson <rpearsonhpe@...il.com> 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@gmail.com
> > Acked-by: Zhu Yanjun <zyjzyj2000@...il.com>
> > Reviewed-by: Bob Pearson <rpearsonhpe@...il.com>
> > Reviewed-by: Paul E. McKenney <paulmck@...nel.org>
> > Fixes: 72a03627443d ("RDMA/rxe: Remove rxe_alloc()")
> > Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
> > ---
> >  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