From: David Gibson <david@gibson.dropbear.id.au>
To: Stefano Brivio <sbrivio@redhat.com>
Cc: passt-dev@passt.top
Subject: Re: [PATCH 03/11] tcp_splice: Don't handle EPOLL_CTL_DEL as part of tcp_splice_epoll_ctl()
Date: Sat, 4 Nov 2023 16:56:37 +1100 [thread overview]
Message-ID: <ZUXdFa4ZE126tmod@zatzit> (raw)
In-Reply-To: <20231103172053.22f07d27@elisabeth>
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On Fri, Nov 03, 2023 at 05:20:53PM +0100, Stefano Brivio wrote:
> On Thu, 12 Oct 2023 12:51:06 +1100
> David Gibson <david@gibson.dropbear.id.au> wrote:
>
> > tcp_splice_epoll_ctl() removes both sockets from the epoll set if called
> > when conn->flags & CLOSING. This will always happen immediately after
> > setting that flag, since conn_flag_do() makes the call itself. That's also
> > the _only_ time it can happen: we perform the EPOLL_CTL_DEL without
> > clearing the conn->in_epoll flag, meaning that any further calls to
> > tcp_splice_epoll_ctl() would attempt EPOLL_CTL_MOD, which would necessarily
> > fail since the fds are no longer in the epoll.
> >
> > The EPOLL_CTL_DEL path in tcp_splice_epoll_ctl() has essentially zero
> > overlap with anything else the function does, so just move them to be
> > open coded in conn_flag_do().
> >
> > Caveat: this does require kernel 2.6.9 or later, in order to pass NULL as
> > the event structure for epoll_ctl(). I _think_ we already require newer
> > kernels than that for other features.
>
> Yes, we do, we need at least 3.13 for unprivileged user namespaces.
Thanks, message updated accordingly.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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next prev parent reply other threads:[~2023-11-04 6:11 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-12 1:51 [PATCH 00/11] tcp_splice: Better exploit symmetry between sides of connection David Gibson
2023-10-12 1:51 ` [PATCH 01/11] tcp_splice: Remove redundant tcp_splice_epoll_ctl() David Gibson
2023-10-12 1:51 ` [PATCH 02/11] tcp_splice: Correct error handling in tcp_splice_epoll_ctl() David Gibson
2023-10-12 1:51 ` [PATCH 03/11] tcp_splice: Don't handle EPOLL_CTL_DEL as part of tcp_splice_epoll_ctl() David Gibson
2023-11-03 16:20 ` Stefano Brivio
2023-11-04 5:56 ` David Gibson [this message]
2023-10-12 1:51 ` [PATCH 04/11] tcp_splice: Remove unnecessary forward declaration David Gibson
2023-10-12 1:51 ` [PATCH 05/11] tcp_splice: Avoid awkward temporaries in tcp_splice_epoll_ctl() David Gibson
2023-11-03 16:21 ` Stefano Brivio
2023-11-04 5:58 ` David Gibson
2023-10-12 1:51 ` [PATCH 06/11] tcp_splice: Don't pool pipes in pairs David Gibson
2023-10-12 1:51 ` [PATCH 07/11] tcp_splice: Rename sides of connection from a/b to 0/1 David Gibson
2023-10-12 1:51 ` [PATCH 08/11] tcp_splice: Exploit side symmetry in tcp_splice_timer() David Gibson
2023-11-03 16:21 ` Stefano Brivio
2023-11-04 5:59 ` David Gibson
2023-10-12 1:51 ` [PATCH 09/11] tcp_splice: Exploit side symmetry in tcp_splice_connect_finish() David Gibson
2023-10-12 1:51 ` [PATCH 10/11] tcp_splice: Exploit side symmetry in tcp_splice_destroy() David Gibson
2023-11-03 16:22 ` Stefano Brivio
2023-11-06 2:39 ` David Gibson
2023-11-06 13:21 ` Stefano Brivio
2023-10-12 1:51 ` [PATCH 11/11] tcp_splice: Simplify selection of socket and pipe sides in socket handler David Gibson
2023-11-03 16:21 ` Stefano Brivio
2023-11-04 6:02 ` David Gibson
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