From: "Toke Høiland-Jørgensen" <toke@redhat•com>
To: Martin KaFai Lau <kafai@fb•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: Fri, 11 Jun 2021 01:19:04 +0200 [thread overview]
Message-ID: <87h7i5ux3r.fsf@toke.dk> (raw)
In-Reply-To: <20210610210907.hgfnlja3hbmgeqxx@kafai-mbp>
Martin KaFai Lau <kafai@fb•com> writes:
> 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()?
Hmm, no, I guess not since that's called from a workqueue. Will fix!
>> @@ -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?
True, can just add that to the check.
>> 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()?
Yup.
next prev parent reply other threads:[~2021-06-10 23:19 UTC|newest]
Thread overview: 37+ 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
2021-06-10 23:19 ` Toke Høiland-Jørgensen [this message]
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 ` [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 ` [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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87h7i5ux3r.fsf@toke.dk \
--to=toke@redhat$(echo .)com \
--cc=bpf@vger$(echo .)kernel.org \
--cc=brouer@redhat$(echo .)com \
--cc=kafai@fb$(echo .)com \
--cc=liuhangbin@gmail$(echo .)com \
--cc=magnus.karlsson@gmail$(echo .)com \
--cc=netdev@vger$(echo .)kernel.org \
--cc=paulmck@kernel$(echo .)org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox