netdev - Re: [PATCH net-next v3 2/2] io_uring: ignore POLLIN for recvmsg on MSG

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Date:   Sat, 22 Aug 2020 09:49:18 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Luke Hsiao <luke.w.hsiao@...il.com>,
        David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, Jakub Kicinski <kuba@...nel.org>,
        Luke Hsiao <lukehsiao@...gle.com>,
        Arjun Roy <arjunroy@...gle.com>,
        Soheil Hassas Yeganeh <soheil@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>
Subject: Re: [PATCH net-next v3 2/2] io_uring: ignore POLLIN for recvmsg on
 MSG_ERRQUEUE

On 8/21/20 10:41 PM, Luke Hsiao wrote:
> From: Luke Hsiao <lukehsiao@...gle.com>
> 
> Currently, io_uring's recvmsg subscribes to both POLLERR and POLLIN. In
> the context of TCP tx zero-copy, this is inefficient since we are only
> reading the error queue and not using recvmsg to read POLLIN responses.
> 
> This patch was tested by using a simple sending program to call recvmsg
> using io_uring with MSG_ERRQUEUE set and verifying with printks that the
> POLLIN is correctly unset when the msg flags are MSG_ERRQUEUE.

Perfect, and ends up being much simpler too and straight forward.

-- 
Jens Axboe