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From: Simon Horman <simon.horman@corigine.com>
To: Eric Dumazet <edumazet@google.com>
Cc: "David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	netdev@vger.kernel.org, eric.dumazet@gmail.com
Subject: Re: [PATCH v2 net 1/2] rfs: annotate lockless accesses to sk->sk_rxhash
Date: Tue, 6 Jun 2023 11:40:03 +0200	[thread overview]
Message-ID: <ZH7+8xU9uVBpaXQl@corigine.com> (raw)
In-Reply-To: <20230606074115.3789733-2-edumazet@google.com>

On Tue, Jun 06, 2023 at 07:41:14AM +0000, Eric Dumazet wrote:
> 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: fec5e652e58f ("rfs: Receive Flow Steering")
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Reviewed-by: Simon Horman <simon.horman@corigine.com>


  reply	other threads:[~2023-06-06  9:40 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-06  7:41 [PATCH v2 net 0/2] rfs: annotate lockless accesses Eric Dumazet
2023-06-06  7:41 ` [PATCH v2 net 1/2] rfs: annotate lockless accesses to sk->sk_rxhash Eric Dumazet
2023-06-06  9:40   ` Simon Horman [this message]
2023-06-06 17:40   ` Kuniyuki Iwashima
2023-06-06  7:41 ` [PATCH v2 net 2/2] rfs: annotate lockless accesses to RFS sock flow table Eric Dumazet
2023-06-06  9:40   ` Simon Horman
2023-06-06 17:42   ` Kuniyuki Iwashima
2023-06-07  9:20 ` [PATCH v2 net 0/2] rfs: annotate lockless accesses patchwork-bot+netdevbpf

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