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Subject: Re: [PATCH net 3/4] net: ravb: Fix GbEth jumbo packet RX checksum
 handling
To: Paul Barker <paul.barker.ct@bp.renesas.com>, "David S. Miller"
	<davem@davemloft.net>, Eric Dumazet <edumazet@google.com>, Jakub Kicinski
	<kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	=?UTF-8?Q?Niklas_S=c3=b6derlund?= <niklas.soderlund+renesas@ragnatech.se>,
	Geert Uytterhoeven <geert+renesas@glider.be>
CC: <netdev@vger.kernel.org>, <linux-renesas-soc@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>
References: <20240411114434.26186-1-paul.barker.ct@bp.renesas.com>
 <20240411114434.26186-4-paul.barker.ct@bp.renesas.com>
From: Sergey Shtylyov <s.shtylyov@omp.ru>
Organization: Open Mobile Platform
Message-ID: <c9c624c0-cd26-bceb-e011-7debce338493@omp.ru>
Date: Thu, 11 Apr 2024 19:50:24 +0300
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On 4/11/24 2:44 PM, Paul Barker wrote:

> Sending a 7kB ping packet to the RZ/G2L in Linux v6.9-rc2 causes the
> following backtrace:
> 
> 	WARNING: CPU: 0 PID: 0 at include/linux/skbuff.h:3127 skb_trim+0x30/0x38
> 	Modules linked in:
> 	CPU: 0 PID: 0 Comm: swapper/0 Tainted: G        W          6.9.0-rc1-00222-gde11614025b1 #3
> 	Hardware name: Renesas SMARC EVK based on r9a07g044l2 (DT)
> 	pstate: 20400005 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> 	pc : skb_trim+0x30/0x38
> 	lr : ravb_rx_csum_gbeth+0x40/0x90
> 	sp : ffff800080003d40
> 	x29: ffff800080003d40 x28: 0000000000000400 x27: ffff00000d0f0000
> 	x26: 0000000000000001 x25: ffff800080003e84 x24: 0000000000000e52
> 	x23: 0000000000000000 x22: ffff00000d0f0960 x21: 000000000000ffff
> 	x20: 000000000000f6ff x19: ffff00000cf4cb00 x18: 0000000000000000
> 	x17: ffff7ffffdd4f000 x16: ffff800080000000 x15: e7e6e5e4e3e2e1e0
> 	x14: dfdedddcdbdad9d8 x13: 0000131211100f0e x12: 0d0c0b0a09080706
> 	x11: 0000000013121110 x10: 0000000000000000 x9 : 0000000000000001
> 	x8 : ffff800080003cf0 x7 : 0000000000000000 x6 : ffff00007faf4590
> 	x5 : 000000000010000b x4 : a1a8362deecb53ea x3 : 0000000000000080
> 	x2 : 00000000ffff0000 x1 : 000000000cf4ccfc x0 : ffff00000cf4cb00
> 	Call trace:
> 	 skb_trim+0x30/0x38
> 	 ravb_rx_gbeth+0x56c/0x5cc
> 	 ravb_poll+0xa0/0x204
> 	 __napi_poll+0x38/0x17c
> 	 net_rx_action+0x124/0x268
> 	 __do_softirq+0x100/0x26c
> 	 ____do_softirq+0x10/0x1c
> 	 call_on_irq_stack+0x24/0x4c
> 	 do_softirq_own_stack+0x1c/0x2c
> 	 irq_exit_rcu+0xbc/0xd8
> 	 el1_interrupt+0x38/0x68
> 	 el1h_64_irq_handler+0x18/0x24
> 	 el1h_64_irq+0x64/0x68
> 	 default_idle_call+0x28/0x3c
> 	 do_idle+0x204/0x25c
> 	 cpu_startup_entry+0x38/0x3c
> 	 kernel_init+0x0/0x1d8
> 	 start_kernel+0x504/0x5f0
> 	 __primary_switched+0x80/0x88
> 	---[ end trace 0000000000000000 ]---
> 
> This is caused by ravb_rx_gbeth() calling ravb_rx_csum_gbeth() with the
> wrong skb for a packet which spans multiple descriptors. To fix this,
> use the correct skb.
> 
> Fixes: c2da9408579d ("ravb: Add Rx checksum offload support for GbEth")
> Signed-off-by: Paul Barker <paul.barker.ct@bp.renesas.com>

Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>

[...]

MBR, Sergey