From: Claudiu Manoil <claudiu.manoil@nxp.com>
To: Eric Dumazet <eric.dumazet@gmail.com>,
Vladimir Oltean <olteanv@gmail.com>
Cc: Jakub Kicinski <kuba@kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"David S . Miller" <davem@davemloft.net>,
"james.jurack@ametek.com" <james.jurack@ametek.com>
Subject: RE: [PATCH net v2 1/2] gianfar: Replace skb_realloc_headroom with skb_cow_head for PTP
Date: Wed, 4 Nov 2020 16:45:02 +0000 [thread overview]
Message-ID: <AM0PR04MB6754884EDFBB94EB16545A1596EF0@AM0PR04MB6754.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <19c3385d-7974-b5bd-3d5a-51d3d87919b0@gmail.com>
>-----Original Message-----
>From: Eric Dumazet <eric.dumazet@gmail.com>
>Sent: Tuesday, November 3, 2020 8:16 PM
>To: Vladimir Oltean <olteanv@gmail.com>; Claudiu Manoil
><claudiu.manoil@nxp.com>
>Cc: Jakub Kicinski <kuba@kernel.org>; netdev@vger.kernel.org; David S .
>Miller <davem@davemloft.net>; james.jurack@ametek.com
>Subject: Re: [PATCH net v2 1/2] gianfar: Replace skb_realloc_headroom with
>skb_cow_head for PTP
>
>
>
>On 11/3/20 6:49 PM, Vladimir Oltean wrote:
>> On Tue, Nov 03, 2020 at 05:41:36PM +0000, Claudiu Manoil wrote:
>>> This is the patch:
>>>
[...]
>>>
>>> are you sure you have it applied?
>>
>> Actually? No, I didn't have it applied... I had thought that net had
>> been already merged into net-next, for some reason :-/
>> Let me run the test for a few more tens of minutes with the patch
>> applied.
>>
>
>I find strange that the local TCP traffic can end up calling
>skb_realloc_headromm() in the old kernels.
>
>Normally TCP reserves a lot of bytes for headers.
>
>#define MAX_TCP_HEADER L1_CACHE_ALIGN(128 + MAX_HEADER)
>
>It should accommodate the gianfar needs for additional 24 bytes,
>even if LL_MAX_HEADER is 32 in your kernel build perhaps.
>
Hi,
The PTP packets need extra headroom and get reallocated, not TCP packets.
However if TCP streams are sent concurrently with PTP packets, and
skb_realloc_headroom() is used to reallocate PTP packets, we get these crashes.
If skb_cow_head() is used instead there's no crash.
next prev parent reply other threads:[~2020-11-04 16:45 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-14 13:53 PROBLEM: Crash when timestamping outgoing PTP packets under heavy network load (ppc, gianfar) James Jurack
2020-10-20 17:36 ` [PATCH net] gianfar: Account for Tx PTP timestamp in the skb headroom Claudiu Manoil
2020-10-21 17:59 ` Jakub Kicinski
2020-10-22 12:09 ` Claudiu Manoil
2020-10-23 2:54 ` Jakub Kicinski
2020-10-23 11:37 ` Claudiu Manoil
2020-10-29 8:10 ` [PATCH net v2 1/2] gianfar: Replace skb_realloc_headroom with skb_cow_head for PTP Claudiu Manoil
2020-10-29 8:10 ` [PATCH net v2 2/2] gianfar: Account for Tx PTP timestamp in the skb headroom Claudiu Manoil
2020-10-30 16:41 ` [PATCH net v2 1/2] gianfar: Replace skb_realloc_headroom with skb_cow_head for PTP Jakub Kicinski
2020-11-03 16:13 ` Vladimir Oltean
2020-11-03 16:30 ` Jakub Kicinski
2020-11-03 17:18 ` Claudiu Manoil
2020-11-03 17:30 ` Vladimir Oltean
2020-11-03 17:36 ` Jakub Kicinski
2020-11-03 17:39 ` Jakub Kicinski
2020-11-03 17:51 ` Vladimir Oltean
2020-11-03 17:41 ` Claudiu Manoil
2020-11-03 17:49 ` Vladimir Oltean
2020-11-03 18:16 ` Eric Dumazet
2020-11-04 16:45 ` Claudiu Manoil [this message]
2020-11-03 18:16 ` Vladimir Oltean
2020-11-03 16:36 ` Julian Wiedmann
2020-11-03 17:08 ` Claudiu Manoil
2020-11-03 17:12 ` Jakub Kicinski
2020-11-03 17:24 ` Vladimir Oltean
2020-11-03 17:38 ` Vladimir Oltean
2020-11-03 17:18 ` Vladimir Oltean
2020-11-03 17:27 ` Vladimir Oltean
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