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[2003:ea:8f38:4600:6dfe:cdb3:c4f9:2744]) by smtp.googlemail.com with ESMTPSA id v18sm50270232wru.85.2021.04.08.10.49.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 08 Apr 2021 10:49:07 -0700 (PDT) Subject: Re: [PATCH net v1] Revert "lan743x: trim all 4 bytes of the FCS; not just 2" To: Sven Van Asbroeck , Bryan Whitehead , David S Miller , Jakub Kicinski , George McCollister Cc: UNGLinuxDriver@microchip.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210408172353.21143-1-TheSven73@gmail.com> From: Heiner Kallweit Message-ID: <42bca8b7-863c-bc2d-7628-075ca18157af@gmail.com> Date: Thu, 8 Apr 2021 19:49:00 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: <20210408172353.21143-1-TheSven73@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08.04.2021 19:23, Sven Van Asbroeck wrote: > From: Sven Van Asbroeck > > This reverts commit 3e21a10fdea3c2e4e4d1b72cb9d720256461af40. > > The reverted patch completely breaks all network connectivity on the > lan7430. tcpdump indicates missing bytes when receiving ping > packets from an external host: > > host$ ping $lan7430_ip > lan7430$ tcpdump -v > IP truncated-ip - 2 bytes missing! (tos 0x0, ttl 64, id 21715, > offset 0, flags [DF], proto ICMP (1), length 84) > > Fixes: 3e21a10fdea3 ("lan743x: trim all 4 bytes of the FCS; not just 2") > Signed-off-by: Sven Van Asbroeck > --- > > To: Bryan Whitehead > To: "David S. Miller" > To: Jakub Kicinski > To: George McCollister > Cc: UNGLinuxDriver@microchip.com > Cc: netdev@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > > drivers/net/ethernet/microchip/lan743x_main.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c > index 1c3e204d727c..dbdfabff3b00 100644 > --- a/drivers/net/ethernet/microchip/lan743x_main.c > +++ b/drivers/net/ethernet/microchip/lan743x_main.c > @@ -2040,7 +2040,7 @@ lan743x_rx_trim_skb(struct sk_buff *skb, int frame_length) > dev_kfree_skb_irq(skb); > return NULL; > } > - frame_length = max_t(int, 0, frame_length - RX_HEAD_PADDING - 4); > + frame_length = max_t(int, 0, frame_length - RX_HEAD_PADDING - 2); > if (skb->len > frame_length) { > skb->tail -= skb->len - frame_length; > skb->len = frame_length; > Can't we use frame_length - ETH_FCS_LEN direcctly here?