__inet_hash_connect() has a fast path taken if sk_head(&tb->owners) is
equal to the sk parameter.
sk_head() returns the hlist_entry() with respect to the sk_node field.
However entries in the tb->owners list are inserted with respect to the
sk_bind_node field with sk_add_bind_node().
Thus the check would never pass and the fast path never execute.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reviewed-by: Kuniyuki Iwashima <[email protected]>
Signed-off-by: Pietro Borrello <[email protected]>
---
Changes in v2:
- nit: s/list_entry/hlist_entry/
- Link to v1: https://lore.kernel.org/r/20230112-inet_hash_connect_bind_head-v1-1-7e3c770157c8@diag.uniroma1.it
---
include/net/sock.h | 10 ++++++++++
net/ipv4/inet_hashtables.c | 2 +-
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index dcd72e6285b2..23fc403284db 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -860,6 +860,16 @@ static inline void sk_nulls_add_node_rcu(struct sock *sk, struct hlist_nulls_hea
__sk_nulls_add_node_rcu(sk, list);
}
+static inline struct sock *__sk_bind_head(const struct hlist_head *head)
+{
+ return hlist_entry(head->first, struct sock, sk_bind_node);
+}
+
+static inline struct sock *sk_bind_head(const struct hlist_head *head)
+{
+ return hlist_empty(head) ? NULL : __sk_bind_head(head);
+}
+
static inline void __sk_del_bind_node(struct sock *sk)
{
__hlist_del(&sk->sk_bind_node);
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index d039b4e732a3..a805e086fb48 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -998,7 +998,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
hinfo->bhash_size)];
tb = inet_csk(sk)->icsk_bind_hash;
spin_lock_bh(&head->lock);
- if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
+ if (sk_bind_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
inet_ehash_nolisten(sk, NULL, NULL);
spin_unlock_bh(&head->lock);
return 0;
---
base-commit: 1b929c02afd37871d5afb9d498426f83432e71c2
change-id: 20230112-inet_hash_connect_bind_head-8f2dc98f08b1
Best regards,
--
Pietro Borrello <[email protected]>
On Fri, Jan 13, 2023 at 12:40 PM Pietro Borrello
<[email protected]> wrote:
>
> __inet_hash_connect() has a fast path taken if sk_head(&tb->owners) is
> equal to the sk parameter.
> sk_head() returns the hlist_entry() with respect to the sk_node field.
> However entries in the tb->owners list are inserted with respect to the
> sk_bind_node field with sk_add_bind_node().
> Thus the check would never pass and the fast path never execute.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Reviewed-by: Kuniyuki Iwashima <[email protected]>
> Signed-off-by: Pietro Borrello <[email protected]>
> ---
> Changes in v2:
> - nit: s/list_entry/hlist_entry/
> - Link to v1: https://lore.kernel.org/r/20230112-inet_hash_connect_bind_head-v1-1-7e3c770157c8@diag.uniroma1.it
> ---
> include/net/sock.h | 10 ++++++++++
> net/ipv4/inet_hashtables.c | 2 +-
> 2 files changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/include/net/sock.h b/include/net/sock.h
> index dcd72e6285b2..23fc403284db 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -860,6 +860,16 @@ static inline void sk_nulls_add_node_rcu(struct sock *sk, struct hlist_nulls_hea
> __sk_nulls_add_node_rcu(sk, list);
> }
>
> +static inline struct sock *__sk_bind_head(const struct hlist_head *head)
> +{
> + return hlist_entry(head->first, struct sock, sk_bind_node);
> +}
> +
> +static inline struct sock *sk_bind_head(const struct hlist_head *head)
> +{
> + return hlist_empty(head) ? NULL : __sk_bind_head(head);
> +}
> +
> static inline void __sk_del_bind_node(struct sock *sk)
> {
> __hlist_del(&sk->sk_bind_node);
> diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
> index d039b4e732a3..a805e086fb48 100644
> --- a/net/ipv4/inet_hashtables.c
> +++ b/net/ipv4/inet_hashtables.c
> @@ -998,7 +998,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
> hinfo->bhash_size)];
> tb = inet_csk(sk)->icsk_bind_hash;
> spin_lock_bh(&head->lock);
> - if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
> + if (sk_bind_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
> inet_ehash_nolisten(sk, NULL, NULL);
1) Given this path was never really used, we have no coverage.
2) Given that we do not check inet_ehash_nolisten() return code here.
I would recommend _not_ adding the Fixes: tag, and target net-next tree
In fact, I would remove this dead code, and reduce complexity.
I doubt the difference is going to be noticed.
(We have to access the ehash bucket anyway)
> spin_unlock_bh(&head->lock);
> return 0;
>
> ---
> base-commit: 1b929c02afd37871d5afb9d498426f83432e71c2
> change-id: 20230112-inet_hash_connect_bind_head-8f2dc98f08b1
>
> Best regards,
> --
> Pietro Borrello <[email protected]>
On Fri, 13 Jan 2023 at 13:16, Eric Dumazet <[email protected]> wrote:
> 1) Given this path was never really used, we have no coverage.
>
> 2) Given that we do not check inet_ehash_nolisten() return code here.
It seems there are a bunch of call sites where inet_ehash_nolisten() return
code is not checked, thus I didn't think of it to be a problem.
>
> I would recommend _not_ adding the Fixes: tag, and target net-next tree
>
> In fact, I would remove this dead code, and reduce complexity.
>
This makes a lot of sense. I can post a v3 patch completely removing
the fast path.
However, this patch's v1 was already reviewed by
Kuniyuki Iwashima <[email protected]>, v2 is a nit, if posting a v3
I think I should remove the Reviewed-by: since it would completely
change the patch, but what is the preferred fix?
Best regards,
Pietro
On Sat, Jan 14, 2023 at 1:18 PM Pietro Borrello
<[email protected]> wrote:
>
> On Fri, 13 Jan 2023 at 13:16, Eric Dumazet <[email protected]> wrote:
> > 1) Given this path was never really used, we have no coverage.
> >
> > 2) Given that we do not check inet_ehash_nolisten() return code here.
>
> It seems there are a bunch of call sites where inet_ehash_nolisten() return
> code is not checked, thus I didn't think of it to be a problem.
>
> >
> > I would recommend _not_ adding the Fixes: tag, and target net-next tree
> >
> > In fact, I would remove this dead code, and reduce complexity.
> >
>
> This makes a lot of sense. I can post a v3 patch completely removing
> the fast path.
>
> However, this patch's v1 was already reviewed by
> Kuniyuki Iwashima <[email protected]>, v2 is a nit, if posting a v3
> I think I should remove the Reviewed-by: since it would completely
> change the patch, but what is the preferred fix?
>
Yes, remove it, and Kuniyuki will review it again, thanks.