From: Martin KaFai Lau <kafai@fb.com>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>,
Hangbin Liu <liuhangbin@gmail.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Magnus Karlsson <magnus.karlsson@gmail.com>,
"Paul E . McKenney" <paulmck@kernel.org>
Subject: Re: [PATCH bpf-next 04/17] xdp: add proper __rcu annotations to redirect map entries
Date: Thu, 10 Jun 2021 14:09:07 -0700 [thread overview]
Message-ID: <20210610210907.hgfnlja3hbmgeqxx@kafai-mbp> (raw)
In-Reply-To: <20210609103326.278782-5-toke@redhat.com>
On Wed, Jun 09, 2021 at 12:33:13PM +0200, Toke Høiland-Jørgensen wrote:
[ ... ]
> @@ -551,7 +551,8 @@ static void cpu_map_free(struct bpf_map *map)
> for (i = 0; i < cmap->map.max_entries; i++) {
> struct bpf_cpu_map_entry *rcpu;
>
> - rcpu = READ_ONCE(cmap->cpu_map[i]);
> + rcpu = rcu_dereference_check(cmap->cpu_map[i],
> + rcu_read_lock_bh_held());
Is rcu_read_lock_bh_held() true during map_free()?
[ ... ]
> @@ -149,7 +152,8 @@ static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value,
> u64 map_flags)
> {
> struct xsk_map *m = container_of(map, struct xsk_map, map);
> - struct xdp_sock *xs, *old_xs, **map_entry;
> + struct xdp_sock __rcu **map_entry;
> + struct xdp_sock *xs, *old_xs;
> u32 i = *(u32 *)key, fd = *(u32 *)value;
> struct xsk_map_node *node;
> struct socket *sock;
> @@ -179,7 +183,7 @@ static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value,
> }
>
> spin_lock_bh(&m->lock);
> - old_xs = READ_ONCE(*map_entry);
> + old_xs = rcu_dereference_check(*map_entry, rcu_read_lock_bh_held());
Is it actually protected by the m->lock at this point?
[ ... ]
> void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs,
> - struct xdp_sock **map_entry)
> + struct xdp_sock __rcu **map_entry)
> {
> spin_lock_bh(&map->lock);
> - if (READ_ONCE(*map_entry) == xs) {
> - WRITE_ONCE(*map_entry, NULL);
> + if (rcu_dereference(*map_entry) == xs) {
nit. rcu_access_pointer()?
> + rcu_assign_pointer(*map_entry, NULL);
> xsk_map_sock_delete(xs, map_entry);
> }
> spin_unlock_bh(&map->lock);
> --
> 2.31.1
>
next prev parent reply other threads:[~2021-06-10 21:09 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-09 10:33 [PATCH bpf-next 00/17] Clean up and document RCU-based object protection for XDP_REDIRECT Toke Høiland-Jørgensen
2021-06-09 10:33 ` [PATCH bpf-next 01/17] rcu: Create an unrcu_pointer() to remove __rcu from a pointer Toke Høiland-Jørgensen
2021-06-09 10:33 ` [PATCH bpf-next 02/17] bpf: allow RCU-protected lookups to happen from bh context Toke Høiland-Jørgensen
2021-06-10 18:38 ` Alexei Starovoitov
2021-06-10 21:24 ` Daniel Borkmann
2021-06-10 22:27 ` Toke Høiland-Jørgensen
2021-06-10 19:33 ` Martin KaFai Lau
2021-06-09 10:33 ` [PATCH bpf-next 03/17] dev: add rcu_read_lock_bh_held() as a valid check when getting a RCU dev ref Toke Høiland-Jørgensen
2021-06-10 19:37 ` Martin KaFai Lau
2021-06-10 23:05 ` Toke Høiland-Jørgensen
2021-06-09 10:33 ` [PATCH bpf-next 04/17] xdp: add proper __rcu annotations to redirect map entries Toke Høiland-Jørgensen
2021-06-10 21:09 ` Martin KaFai Lau [this message]
2021-06-10 23:19 ` Toke Høiland-Jørgensen
2021-06-10 23:32 ` Martin KaFai Lau
2021-06-10 23:41 ` Toke Høiland-Jørgensen
2021-06-09 10:33 ` [PATCH bpf-next 05/17] ena: remove rcu_read_lock() around XDP program invocation Toke Høiland-Jørgensen
2021-06-09 13:57 ` Paul E. McKenney
2021-06-09 10:33 ` [PATCH bpf-next 06/17] bnxt: " Toke Høiland-Jørgensen
2021-06-09 13:58 ` Paul E. McKenney
2021-06-10 8:47 ` Toke Høiland-Jørgensen
2021-06-09 10:33 ` [PATCH bpf-next 07/17] thunderx: " Toke Høiland-Jørgensen
2021-06-09 10:33 ` Toke Høiland-Jørgensen
2021-06-09 10:33 ` [PATCH bpf-next 08/17] freescale: " Toke Høiland-Jørgensen
2021-06-09 10:33 ` [PATCH bpf-next 09/17] net: intel: " Toke Høiland-Jørgensen
2021-06-09 10:33 ` [Intel-wired-lan] " Toke =?unknown-8bit?q?H=C3=B8iland-J=C3=B8rgensen?=
2021-06-09 10:33 ` [PATCH bpf-next 10/17] marvell: " Toke Høiland-Jørgensen
2021-06-09 10:33 ` [PATCH bpf-next 11/17] mlx4: " Toke Høiland-Jørgensen
2021-06-10 7:10 ` Tariq Toukan
2021-06-09 10:33 ` [PATCH bpf-next 12/17] nfp: " Toke Høiland-Jørgensen
2021-06-11 16:30 ` Simon Horman
2021-06-09 10:33 ` [PATCH bpf-next 13/17] qede: " Toke Høiland-Jørgensen
2021-06-09 10:33 ` [PATCH bpf-next 14/17] sfc: " Toke Høiland-Jørgensen
2021-06-09 12:15 ` Edward Cree
2021-06-09 10:33 ` [PATCH bpf-next 15/17] netsec: " Toke Høiland-Jørgensen
2021-06-10 5:30 ` Ilias Apalodimas
2021-06-09 10:33 ` [PATCH bpf-next 16/17] stmmac: " Toke Høiland-Jørgensen
2021-06-09 10:33 ` [PATCH bpf-next 17/17] net: ti: " Toke Høiland-Jørgensen
2021-06-09 17:04 ` Grygorii Strashko
2021-06-10 0:18 ` [PATCH bpf-next 00/17] Clean up and document RCU-based object protection for XDP_REDIRECT Yonghong Song
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