netdev - Re: [PATCH net-next 3/8] cadence: macb: Add page pool support handle multi-descriptor frame rx

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <DFYLWF9IATJE.H6R8RUZQI1FG@bootlin.com>
Date: Mon, 26 Jan 2026 15:55:49 +0100
From: Théo Lebrun <theo.lebrun@...tlin.com>
To: "Paolo Valerio" <pvalerio@...hat.com>, <netdev@...r.kernel.org>
Cc: "Nicolas Ferre" <nicolas.ferre@...rochip.com>, "Claudiu Beznea"
 <claudiu.beznea@...on.dev>, "Andrew Lunn" <andrew+netdev@...n.ch>, "David
 S. Miller" <davem@...emloft.net>, "Eric Dumazet" <edumazet@...gle.com>,
 "Jakub Kicinski" <kuba@...nel.org>, "Paolo Abeni" <pabeni@...hat.com>,
 "Lorenzo Bianconi" <lorenzo@...nel.org>, Théo Lebrun
 <theo.lebrun@...tlin.com>, Grégory Clement
 <gregory.clement@...tlin.com>, "Thomas Petazzoni"
 <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH net-next 3/8] cadence: macb: Add page pool support
 handle multi-descriptor frame rx

Hi Paolo,

On Thu Jan 15, 2026 at 11:25 PM CET, Paolo Valerio wrote:
> Use the page pool allocator for the data buffers and enable skb recycling
> support, instead of relying on netdev_alloc_skb allocating the entire skb
> during the refill.
>
> The patch also add support for receiving network frames that span multiple
> DMA descriptors in the Cadence MACB/GEM Ethernet driver.
>
> The patch removes the requirement that limited frame reception to
> a single descriptor (RX_SOF && RX_EOF), also avoiding potential
> contiguous multi-page allocation for large frames.

[...]

> --- a/drivers/net/ethernet/cadence/macb.h
> +++ b/drivers/net/ethernet/cadence/macb.h
> @@ -14,6 +14,7 @@
>  #include <linux/interrupt.h>
>  #include <linux/phy/phy.h>
>  #include <linux/workqueue.h>
> +#include <net/page_pool/helpers.h>
>  
>  #define MACB_GREGS_NBR 16
>  #define MACB_GREGS_VERSION 2
> @@ -1266,6 +1267,8 @@ struct macb_queue {
>  	void			*rx_buffers;
>  	struct napi_struct	napi_rx;
>  	struct queue_stats stats;
> +	struct page_pool	*page_pool;
> +	struct sk_buff		*skb;

There might be a cleanup issue with the GRO queue->skb field.
It gets cleaned up by gem_rx() in
 - various error codepaths with the free_frags label, or,
 - the happy path where we hand off the skb with napi_gro_receive().

If we get closed in the middle of a transfer we have queue->skb that is
valid. It sounds like an issue if we shutdown (and leak the SKB) or if
we reopen (and have the old SKB laying around). I have not encountered
this on HW, but I haven't tried.

Do you agree? A job for gem_free_rx_buffers()?

Thanks,

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com