patches for DPDK stable branches
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From: Stephen Hemminger <>
To: "Loftus, Ciara" <>
Cc: "" <>,
	"" <>,
	"Yigit, Ferruh" <>,
	"Zhang, Qi Z" <>,
	"Burakov, Anatoly" <>
Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH] net/af_xdp: fix support of secondary process
Date: Mon, 20 Sep 2021 07:43:37 -0700	[thread overview]
Message-ID: <20210920074337.595f3742@hermes.local> (raw)
In-Reply-To: <>

On Mon, 20 Sep 2021 13:23:57 +0000
"Loftus, Ciara" <> wrote:

> > -----Original Message-----
> > From: dev <> On Behalf Of Stephen Hemminger
> > Sent: Friday 3 September 2021 17:15
> > To:
> > Cc: Stephen Hemminger <>;
> >;
> > Subject: [dpdk-dev] [PATCH] net/af_xdp: fix support of secondary process
> > 
> > Doing basic operations like info_get or get_stats was broken
> > in af_xdp PMD. The info_get would crash because dev->device
> > was NULL in secondary process. Fix this by doing same initialization
> > as af_packet and tap devices.
> > 
> > The get_stats would crash because the XDP socket is not open in
> > primary process. As a workaround don't query kernel for dropped
> > packets when called from secondary process.
> > 
> > Note: this does not address the other bug which is that transmitting
> > in secondary process is broken because the send() in tx_kick
> > will fail because XDP socket fd is not valid in secondary process.  
> Hi Stephen,
> Apologies for the delayed reply, I was on vacation.
> In the Bugzilla report you suggest we:
> "mark AF_XDP as broken in with primary/secondary
> and return an error in probe in secondary process".
> I agree with this suggestion. However with this patch we still permit secondary, and just make sure it doesn't crash for get_stats. Did you change your mind?
> Personally, I would prefer to have primary/secondary either working 100% or else not allowed at all by throwing an error during probe. What do you think? Do you have a reason/use case to permit secondary processes despite some features not being available eg. full stats, tx?
> Thanks,
> Ciara

There are two cases where secondary is useful even if send/receive can't work from secondary process.
The pdump and proc-info applications can work with these patches.

I am using XDP over pdump as an easy way to get packets into the code for testing.

The flag in the documentation doesn't have a "limited" version.
If you want, will send another patch to disable secondary support.

Supporting secondary, means adding a mechanism to pass the socket around.

  reply	other threads:[~2021-09-20 14:43 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-03 16:15 [dpdk-stable] " Stephen Hemminger
2021-09-15  8:19 ` Ferruh Yigit
2021-09-20 13:23 ` [dpdk-stable] [dpdk-dev] " Loftus, Ciara
2021-09-20 14:43   ` Stephen Hemminger [this message]
2021-09-20 15:09     ` Loftus, Ciara
2021-09-21 17:45       ` Stephen Hemminger
2021-09-23 12:33         ` Loftus, Ciara
2021-10-05 15:02           ` Ferruh Yigit

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