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Message-ID: <21e7c87a-7680-bdf0-5290-90126741935f@siemens.com>
Date:   Tue, 1 Feb 2022 07:44:33 +0100
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Subject: Re: [PATCH] ipheth: fix EOVERFLOW in ipheth_rcvbulk_callback
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To:     Jakub Kicinski <kuba@kernel.org>
CC:     "David S. Miller" <davem@davemloft.net>,
        Georgi Valkov <gvalkov@abv.bg>,
        linux-usb <linux-usb@vger.kernel.org>,
        Linux Netdev List <netdev@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
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From:   Jan Kiszka <jan.kiszka@siemens.com>
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On 01.02.22 06:14, Jakub Kicinski wrote:
> On Mon, 31 Jan 2022 19:58:14 +0100 Jan Kiszka wrote:
>> From: Georgi Valkov <gvalkov@abv.bg>
>>
>> When rx_buf is allocated we need to account for IPHETH_IP_ALIGN,
>> which reduces the usable size by 2 bytes. Otherwise we have 1512
>> bytes usable instead of 1514, and if we receive more than 1512
>> bytes, ipheth_rcvbulk_callback is called with status -EOVERFLOW,
>> after which the driver malfunctiones and all communication stops.
>>
>> Resolves ipheth 2-1:4.2: ipheth_rcvbulk_callback: urb status: -75
>>
>> Fixes: f33d9e2b48a3 ("usbnet: ipheth: fix connectivity with iOS 14")
>> Signed-off-by: Georgi Valkov <gvalkov@abv.bg>
>> Tested-by: Jan Kiszka <jan.kiszka@siemens.com>
> 
> Hm, I'm starting to suspect this patch is cursed..
> 
>> diff --git a/drivers/net/usb/ipheth.c b/drivers/net/usb/ipheth.c
>> index cd33955df0b6..6a769df0b421 100644
>> --- a/drivers/net/usb/ipheth.c
>> +++ b/drivers/net/usb/ipheth.c
>> @@ -121,7 +121,7 @@ static int ipheth_alloc_urbs(struct ipheth_device *iphone)
>>    	if (tx_buf == NULL)
> 
> There is an extra space character at the start of each line of context.
> 
>>    		goto free_rx_urb;
>>    
>> -	rx_buf = usb_alloc_coherent(iphone->udev, IPHETH_BUF_SIZE,
> 
> But not on the changed lines.
> 
>> +	rx_buf = usb_alloc_coherent(iphone->udev, IPHETH_BUF_SIZE + IPHETH_IP_ALIGN,
>>    				    GFP_KERNEL, &rx_urb->transfer_dma);
>>    	if (rx_buf == NULL)
>>    		goto free_tx_buf;
>> @@ -146,7 +146,7 @@ static int ipheth_alloc_urbs(struct ipheth_device *iphone)
>>    
>>    static void ipheth_free_urbs(struct ipheth_device *iphone)
>>    {
>> -	usb_free_coherent(iphone->udev, IPHETH_BUF_SIZE, iphone->rx_buf,
> 
> Pretty clear here in how the opening bracket does not align after the -.
> 
>> +	usb_free_coherent(iphone->udev, IPHETH_BUF_SIZE + IPHETH_IP_ALIGN, iphone->rx_buf,
>>    			  iphone->rx_urb->transfer_dma);
>>    	usb_free_coherent(iphone->udev, IPHETH_BUF_SIZE, iphone->tx_buf,
>>    			  iphone->tx_urb->transfer_dma);
>> @@ -317,7 +317,7 @@ static int ipheth_rx_submit(struct ipheth_device *dev, gfp_t mem_flags)
>>    
>>    	usb_fill_bulk_urb(dev->rx_urb, udev,
>>    			  usb_rcvbulkpipe(udev, dev->bulk_in),
>> -			  dev->rx_buf, IPHETH_BUF_SIZE,
>> +			  dev->rx_buf, IPHETH_BUF_SIZE + IPHETH_IP_ALIGN,
>>    			  ipheth_rcvbulk_callback,
>>    			  dev);
>>    	dev->rx_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
> 

Sorry, a submission tool regressed here unnoticed (grrrr!). Will resend.

Jan

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