netdev - Re: [PATCH v2 net-next] tcp: fix zerocopy and notsent

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Date:   Tue, 26 Mar 2019 19:52:09 -0000 (UTC)
From:   Holger Hoffstätte 
        <holger@...lied-asynchrony.com>
To:     netdev@...r.kernel.org
Subject: Re: [PATCH v2 net-next] tcp: fix zerocopy and notsent_lowat issues

On Tue, 26 Mar 2019 08:34:55 -0700, Eric Dumazet wrote:

> My recent patch had at least three problems :
> 
> 1) TX zerocopy wants notification when skb is acknowledged,
>    thus we need to call skb_zcopy_clear() if the skb is
>    cached into sk->sk_tx_skb_cache
> 
> 2) Some applications might expect precise EPOLLOUT
>    notifications, so we need to update sk->sk_wmem_queued
>    and call sk_mem_uncharge() from sk_wmem_free_skb()
>    in all cases. The SOCK_QUEUE_SHRUNK flag must also be set.
> 
> 3) Reuse of saved skb should have used skb_cloned() instead
>   of simply checking if the fast clone has been freed.
> 
> Fixes: 472c2e07eef0 ("tcp: add one skb cache for tx")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: Willem de Bruijn <willemb@...gle.com>
> Cc: Soheil Hassas Yeganeh <soheil@...gle.com>

The v1 of this patch caused a lot of oopsies, but this one
works fine. So:

Tested-by: Holger Hoffstätte <holger@...lied-asynchrony.com>

cheers,
Holger