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[85.204.121.218]) by smtp.gmail.com with ESMTPSA id i17sm1064714lfj.35.2019.10.17.03.27.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Oct 2019 03:27:11 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 52C9A1804C9; Thu, 17 Oct 2019 12:27:11 +0200 (CEST) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Martin Lau Cc: "daniel\@iogearbox.net" , Alexei Starovoitov , "bpf\@vger.kernel.org" , "netdev\@vger.kernel.org" , Tetsuo Handa Subject: Re: [PATCH bpf] xdp: Handle device unregister for devmap_hash map type In-Reply-To: <20191016162357.b2kdf6cflw3c5gzb@kafai-mbp.dhcp.thefacebook.com> References: <20191016132802.2760149-1-toke@redhat.com> <20191016162357.b2kdf6cflw3c5gzb@kafai-mbp.dhcp.thefacebook.com> X-Clacks-Overhead: GNU Terry Pratchett Date: Thu, 17 Oct 2019 12:27:11 +0200 Message-ID: <87imonfz0g.fsf@toke.dk> MIME-Version: 1.0 X-MC-Unique: mwqPtjEQMFWWMYSRXdgE7A-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Martin Lau writes: > On Wed, Oct 16, 2019 at 03:28:02PM +0200, Toke H=C3=B8iland-J=C3=B8rgense= n wrote: >> It seems I forgot to add handling of devmap_hash type maps to the device >> unregister hook for devmaps. This omission causes devices to not be >> properly released, which causes hangs. >>=20 >> Fix this by adding the missing handler. >>=20 >> Fixes: 6f9d451ab1a3 ("xdp: Add devmap_hash map type for looking up devic= es by hashed index") >> Reported-by: Tetsuo Handa >> Signed-off-by: Toke H=C3=B8iland-J=C3=B8rgensen >> --- >> kernel/bpf/devmap.c | 34 ++++++++++++++++++++++++++++++++++ >> 1 file changed, 34 insertions(+) >>=20 >> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c >> index d27f3b60ff6d..deb9416341e9 100644 >> --- a/kernel/bpf/devmap.c >> +++ b/kernel/bpf/devmap.c >> @@ -719,6 +719,35 @@ const struct bpf_map_ops dev_map_hash_ops =3D { >> =09.map_check_btf =3D map_check_no_btf, >> }; >> =20 >> +static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab, >> +=09=09=09=09 struct net_device *netdev) >> +{ >> +=09int i; >> + >> +=09for (i =3D 0; i < dtab->n_buckets; i++) { >> +=09=09struct bpf_dtab_netdev *dev, *odev; >> +=09=09struct hlist_head *head; >> + >> +=09=09head =3D dev_map_index_hash(dtab, i); >> +=09=09dev =3D hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head= )), >> +=09=09=09=09 struct bpf_dtab_netdev, >> +=09=09=09=09 index_hlist); >> + >> +=09=09while (dev) { >> +=09=09=09odev =3D (netdev =3D=3D dev->dev) ? dev : NULL; >> +=09=09=09dev =3D hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&d= ev->index_hlist)), >> +=09=09=09=09=09 struct bpf_dtab_netdev, >> +=09=09=09=09=09 index_hlist); >> + >> +=09=09=09if (odev) { >> +=09=09=09=09hlist_del_rcu(&odev->index_hlist); > Would it race with the dev_map_hash's update/delete side? Oh, right, seems I forgot to grab the lock; will send a v2! -Toke