xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

rfs: annotate lockless accesses to sk->sk_rxhash

Browse Source 
[ Upstream commit 1e5c647c3f6d4f8497dedcd226204e1880e0ffb3 ]

Add READ_ONCE()/WRITE_ONCE() on accesses to sk->sk_rxhash.

This also prevents a (smart ?) compiler to remove the condition in:

if (sk->sk_rxhash != newval)
	sk->sk_rxhash = newval;

We need the condition to avoid dirtying a shared cache line.

Fixes: fec5e652e5 ("rfs: Receive Flow Steering")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Eric Dumazet
2023-06-06 07:41:14 +00:00
committed by Greg Kroah-Hartman
parent 86e3981ff1
commit c62ca9d037
1 changed files with 13 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
include/net/sock.h
View File

@@ -1073,8 +1073,12 @@ static inline void sock_rps_record_flow(const struct sock *sk)
* OR an additional socket flag * OR an additional socket flag
* [1] : sk_state and sk_prot are in the same cache line. * [1] : sk_state and sk_prot are in the same cache line.
*/ */
if (sk->sk_state == TCP_ESTABLISHED) if (sk->sk_state == TCP_ESTABLISHED) {
sock_rps_record_flow_hash(sk->sk_rxhash); /* 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));
}
} }
#endif #endif
} }
@@ -1083,15 +1087,19 @@ static inline void sock_rps_save_rxhash(struct sock *sk,
const struct sk_buff *skb) const struct sk_buff *skb)
{ {
#ifdef CONFIG_RPS #ifdef CONFIG_RPS
if (unlikely(sk->sk_rxhash != skb->hash)) /* The following WRITE_ONCE() is paired with the READ_ONCE()
sk->sk_rxhash = skb->hash; * here, and another one in sock_rps_record_flow().
*/
if (unlikely(READ_ONCE(sk->sk_rxhash) != skb->hash))
WRITE_ONCE(sk->sk_rxhash, skb->hash);
#endif #endif
} }
static inline void sock_rps_reset_rxhash(struct sock *sk) static inline void sock_rps_reset_rxhash(struct sock *sk)
{ {
#ifdef CONFIG_RPS #ifdef CONFIG_RPS
sk->sk_rxhash = 0; /* Paired with READ_ONCE() in sock_rps_record_flow() */
WRITE_ONCE(sk->sk_rxhash, 0);
#endif #endif
} }