From: Thomas Graf <tgraf@suug.ch>
To: Tom Herbert <tom@herbertland.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Brenden Blanco <bblanco@plumgrid.com>,
"David S. Miller" <davem@davemloft.net>,
Linux Kernel Network Developers <netdev@vger.kernel.org>,
Jamal Hadi Salim <jhs@mojatatu.com>,
Saeed Mahameed <saeedm@dev.mellanox.co.il>,
Martin KaFai Lau <kafai@fb.com>, Ari Saha <as754m@att.com>,
Or Gerlitz <gerlitz.or@gmail.com>,
john fastabend <john.fastabend@gmail.com>,
Hannes Frederic Sowa <hannes@stressinduktion.org>,
Daniel Borkmann <daniel@iogearbox.net>
Subject: Re: [PATCH v8 04/11] net/mlx4_en: add support for fast rx drop bpf program
Date: Mon, 18 Jul 2016 14:48:11 +0200 [thread overview]
Message-ID: <20160718124811.GB2979@pox.localdomain> (raw)
In-Reply-To: <CALx6S35a5jEbSLbDCMQ9Q7ngf2sAShsDdLZj+o-43ocOPb3N_A@mail.gmail.com>
On 07/18/16 at 01:39pm, Tom Herbert wrote:
> On Mon, Jul 18, 2016 at 11:10 AM, Thomas Graf <tgraf@suug.ch> wrote:
> > I agree with that but I would like to keep the current per net_device
> > atomic properties.
>
> I don't see that see that there is any synchronization guarantees
> using xchg. For instance, if the pointer is set right after being read
> by a thread for one queue and right before being read by a thread for
> another queue, this could result in the old and new program running
> concurrently or old one running after new. If we need to synchronize
> the operation across all queues then sequence
> ifdown,modify-config,ifup will work.
Right, there are no synchronization guarantees between threads and I
don't think that's needed. The guarantee that is provided is that if
I replace a BPF program, the replace either succeeds in which case
all packets have been either processed by the old or new program. Or
the replace failed in which case the old program was left intact and
all packets are still going through the old program.
This is a nice atomic replacement principle which would be nice to
preserve.
next prev parent reply other threads:[~2016-07-18 12:48 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-12 7:51 [PATCH v8 00/11] Add driver bpf hook for early packet drop and forwarding Brenden Blanco
2016-07-12 7:51 ` [PATCH v8 01/11] bpf: add XDP prog type for early driver filter Brenden Blanco
2016-07-12 13:14 ` Jesper Dangaard Brouer
2016-07-12 14:52 ` Tom Herbert
2016-07-12 16:08 ` Jakub Kicinski
2016-07-13 4:14 ` Alexei Starovoitov
2016-07-12 7:51 ` [PATCH v8 02/11] net: add ndo to setup/query xdp prog in adapter rx Brenden Blanco
2016-07-12 7:51 ` [PATCH v8 03/11] rtnl: add option for setting link xdp prog Brenden Blanco
2016-07-12 7:51 ` [PATCH v8 04/11] net/mlx4_en: add support for fast rx drop bpf program Brenden Blanco
2016-07-12 12:02 ` Tariq Toukan
2016-07-13 11:27 ` David Laight
2016-07-13 14:08 ` Brenden Blanco
2016-07-14 7:25 ` Jesper Dangaard Brouer
2016-07-15 3:30 ` Alexei Starovoitov
2016-07-15 8:21 ` Jesper Dangaard Brouer
2016-07-15 16:56 ` Alexei Starovoitov
2016-07-15 16:18 ` Tom Herbert
2016-07-15 16:47 ` Alexei Starovoitov
2016-07-15 17:49 ` Tom Herbert
2016-07-18 9:10 ` Thomas Graf
2016-07-18 11:39 ` Tom Herbert
2016-07-18 12:48 ` Thomas Graf [this message]
2016-07-18 13:07 ` Tom Herbert
2016-07-19 2:45 ` Alexei Starovoitov
2016-07-18 19:03 ` Brenden Blanco
2016-07-15 19:09 ` Jesper Dangaard Brouer
2016-07-18 4:01 ` Alexei Starovoitov
2016-07-18 8:35 ` Daniel Borkmann
2016-07-15 18:08 ` Tom Herbert
2016-07-15 18:45 ` Jesper Dangaard Brouer
2016-07-12 7:51 ` [PATCH v8 05/11] Add sample for adding simple drop program to link Brenden Blanco
2016-07-12 7:51 ` [PATCH v8 06/11] net/mlx4_en: add page recycle to prepare rx ring for tx support Brenden Blanco
2016-07-12 12:09 ` Tariq Toukan
2016-07-12 21:18 ` David Miller
2016-07-13 0:54 ` Brenden Blanco
2016-07-13 7:17 ` Tariq Toukan
2016-07-13 15:40 ` Brenden Blanco
2016-07-15 21:52 ` Brenden Blanco
[not found] ` <6d638467-eea6-d3e1-6984-88a1198ef303@gmail.com>
2016-07-19 17:41 ` Brenden Blanco
2016-07-12 7:51 ` [PATCH v8 07/11] bpf: add XDP_TX xdp_action for direct forwarding Brenden Blanco
2016-07-12 7:51 ` [PATCH v8 08/11] net/mlx4_en: break out tx_desc write into separate function Brenden Blanco
2016-07-12 12:16 ` Tariq Toukan
2016-07-12 7:51 ` [PATCH v8 09/11] net/mlx4_en: add xdp forwarding and data write support Brenden Blanco
2016-07-12 7:51 ` [PATCH v8 10/11] bpf: enable direct packet data write for xdp progs Brenden Blanco
2016-07-12 7:51 ` [PATCH v8 11/11] bpf: add sample for xdp forwarding and rewrite Brenden Blanco
2016-07-12 14:38 ` [PATCH v8 00/11] Add driver bpf hook for early packet drop and forwarding Tariq Toukan
2016-07-13 15:00 ` Tariq Toukan
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