netdev - Re: [PATCH v2 net-next 7/7] tcp: make tcp_sendmsg() aware of socket backlog

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Message-ID: <1461906355.5535.141.camel@edumazet-glaptop3.roam.corp.google.com>
Date:	Thu, 28 Apr 2016 22:05:55 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Alexei Starovoitov <ast@...com>
Cc:	Eric Dumazet <edumazet@...gle.com>,
	"David S . Miller" <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	Soheil Hassas Yeganeh <soheil@...gle.com>,
	Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Subject: Re: [PATCH v2 net-next 7/7] tcp: make tcp_sendmsg() aware of socket
 backlog

On Thu, 2016-04-28 at 21:43 -0700, Alexei Starovoitov wrote:

> 
> I don't understand the logic completely, but isn't it
> safer to do 'goto wait_for_memory;' here if we happened
> to hit this in the middle of the loop?

Well, the wait_for_memory pushes data, and could early return to user
space with short writes (non blocking IO). This would break things...

After processing backlog, tcp_send_mss() needs to be called again,
and we also need to check sk_err and sk_shutdown. A goto looks fine to
me.

> Also does it make sense to rename __release_sock to
> something like _ _ _sk_flush_backlog, since that's
> what it's doing and not doing any 'release' ?

Well, I guess it could be renamed, but this has been named like that for
decades ? Why changing now, while this patch does not touch it ?