From: Christoph Paasch <cpaa...@openai.com>
Add a helper to check if RFS is needed or not. Allows to make the code a
bit cleaner and the next patch to have MPTCP use this helper to decide
whether or not to iterate over the subflows.
tun_flow_update() was calling sock_rps_record_flow_hash() regardless of
the state of rfs_needed. This was not really a bug as sock_flow_table
simply ends up being NULL and thus everything will be fine.
This commit here thus also implicitly makes tun_flow_update() respect
the state of rfs_needed.
Suggested-by: Matthieu Baerts <matt...@kernel.org>
Signed-off-by: Christoph Paasch <cpaa...@openai.com>
Acked-by: Matthieu Baerts (NGI0) <matt...@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matt...@kernel.org>
---
include/net/rps.h | 85 ++++++++++++++++++++++++++++++++++++-------------------
1 file changed, 56 insertions(+), 29 deletions(-)
diff --git a/include/net/rps.h b/include/net/rps.h
index
9917dce42ca457e9c25d9e84ee450235f771d09b..f1794cd2e7fb32a36bde9959fab651663ab190fd
100644
--- a/include/net/rps.h
+++ b/include/net/rps.h
@@ -85,11 +85,8 @@ static inline void rps_record_sock_flow(struct
rps_sock_flow_table *table,
WRITE_ONCE(table->ents[index], val);
}
-#endif /* CONFIG_RPS */
-
-static inline void sock_rps_record_flow_hash(__u32 hash)
+static inline void _sock_rps_record_flow_hash(__u32 hash)
{
-#ifdef CONFIG_RPS
struct rps_sock_flow_table *sock_flow_table;
if (!hash)
@@ -99,42 +96,33 @@ static inline void sock_rps_record_flow_hash(__u32 hash)
if (sock_flow_table)
rps_record_sock_flow(sock_flow_table, hash);
rcu_read_unlock();
-#endif
}
-static inline void sock_rps_record_flow(const struct sock *sk)
+static inline void _sock_rps_record_flow(const struct sock *sk)
{
-#ifdef CONFIG_RPS
- if (static_branch_unlikely(&rfs_needed)) {
- /* Reading sk->sk_rxhash might incur an expensive cache line
- * miss.
- *
- * TCP_ESTABLISHED does cover almost all states where RFS
- * might be useful, and is cheaper [1] than testing :
- * IPv4: inet_sk(sk)->inet_daddr
- * IPv6: ipv6_addr_any(&sk->sk_v6_daddr)
- * OR an additional socket flag
- * [1] : sk_state and sk_prot are in the same cache line.
+ /* Reading sk->sk_rxhash might incur an expensive cache line
+ * miss.
+ *
+ * TCP_ESTABLISHED does cover almost all states where RFS
+ * might be useful, and is cheaper [1] than testing :
+ * IPv4: inet_sk(sk)->inet_daddr
+ * IPv6: ipv6_addr_any(&sk->sk_v6_daddr)
+ * OR an additional socket flag
+ * [1] : sk_state and sk_prot are in the same cache line.
+ */
+ if (sk->sk_state == TCP_ESTABLISHED) {
+ /* This READ_ONCE() is paired with the WRITE_ONCE()
+ * from sock_rps_save_rxhash() and sock_rps_reset_rxhash().
*/
- if (sk->sk_state == TCP_ESTABLISHED) {
- /* This READ_ONCE() is paired with the WRITE_ONCE()
- * from sock_rps_save_rxhash() and
sock_rps_reset_rxhash().
- */
- sock_rps_record_flow_hash(READ_ONCE(sk->sk_rxhash));
- }
+ _sock_rps_record_flow_hash(READ_ONCE(sk->sk_rxhash));
}
-#endif
}
-static inline void sock_rps_delete_flow(const struct sock *sk)
+static inline void _sock_rps_delete_flow(const struct sock *sk)
{
-#ifdef CONFIG_RPS
struct rps_sock_flow_table *table;
u32 hash, index;
- if (!static_branch_unlikely(&rfs_needed))
- return;
-
hash = READ_ONCE(sk->sk_rxhash);
if (!hash)
return;
@@ -147,6 +135,45 @@ static inline void sock_rps_delete_flow(const struct sock
*sk)
WRITE_ONCE(table->ents[index], RPS_NO_CPU);
}
rcu_read_unlock();
+}
+#endif /* CONFIG_RPS */
+
+static inline bool rfs_is_needed(void)
+{
+#ifdef CONFIG_RPS
+ return static_branch_unlikely(&rfs_needed);
+#else
+ return false;
+#endif
+}
+
+static inline void sock_rps_record_flow_hash(__u32 hash)
+{
+#ifdef CONFIG_RPS
+ if (!rfs_is_needed())
+ return;
+
+ _sock_rps_record_flow_hash(hash);
+#endif
+}
+
+static inline void sock_rps_record_flow(const struct sock *sk)
+{
+#ifdef CONFIG_RPS
+ if (!rfs_is_needed())
+ return;
+
+ _sock_rps_record_flow(sk);
+#endif
+}
+
+static inline void sock_rps_delete_flow(const struct sock *sk)
+{
+#ifdef CONFIG_RPS
+ if (!rfs_is_needed())
+ return;
+
+ _sock_rps_delete_flow(sk);
#endif
}
--
2.51.0
