Re: [PATCH] b43: fix regression in PIO case

[Larry Finger <Larry.Finger@lwfinger.net>]

On 12/26/2011 12:17 PM, Guennadi Liakhovetski wrote:
> On Mon, 26 Dec 2011, Larry Finger wrote:
>
>> On 12/26/2011 11:28 AM, Guennadi Liakhovetski wrote:
>>> This patch fixes the regression, introduced by
>>>
>>> commit 17030f48e31adde5b043741c91ba143f5f7db0fd
>>> From: Rafał Miłecki<zajec5@gmail.com>
>>> Date: Thu, 11 Aug 2011 17:16:27 +0200
>>> Subject: [PATCH] b43: support new RX header, noticed to be used in 598.314+
>>> fw
>>>
>>> in PIO case.
>>>
>>> Signed-off-by: Guennadi Liakhovetski<g.liakhovetski@gmx.de>
>>> ---
>>> diff --git a/drivers/net/wireless/b43/pio.c b/drivers/net/wireless/b43/pio.c
>>> index ce8a4bd..b64b64c 100644
>>> --- a/drivers/net/wireless/b43/pio.c
>>> +++ b/drivers/net/wireless/b43/pio.c
>>> @@ -617,9 +617,19 @@ static bool pio_rx_frame(struct b43_pio_rxqueue *q)
>>>    	const char *err_msg = NULL;
>>>    	struct b43_rxhdr_fw4 *rxhdr =
>>>    		(struct b43_rxhdr_fw4 *)wl->pio_scratchspace;
>>> +	size_t rxhdr_size = sizeof(*rxhdr);
>>>
>>>    	BUILD_BUG_ON(sizeof(wl->pio_scratchspace)<   sizeof(*rxhdr));
>>> -	memset(rxhdr, 0, sizeof(*rxhdr));
>>> +	switch (dev->fw.hdr_format) {
>>> +	case B43_FW_HDR_410:
>>> +	case B43_FW_HDR_351:
>>> +		rxhdr_size -= sizeof(rxhdr->format_598) -
>>> +			sizeof(rxhdr->format_351);
>>> +		break;
>>> +	case B43_FW_HDR_598:
>>> +		break;
>>> +	}
>>
>> I do not think the above will work for format_410. By my count, the format_410
>> struct is 4 bytes longer than the format_351 struct.
>
> I think you're looking at struct b43_txhdr, whereas the problem is in
> struct b43_rxhdr_fw4.
>
> Thanks
> Guennadi
>
>>
>> Even if it does work, I suggest using the following:
>>
>> 	size_t rxhdr_size;
>>
>>     	BUILD_BUG_ON(sizeof(wl->pio_scratchspace)<   sizeof(*rxhdr));
>> 	switch (dev->fw.hdr_format) {
>> 	case B43_FW_HDR_351:
>> 		rxhdr_size = sizeof(rxhdr->format_351);
>> 		break;
>> 	case B43_FW_HDR_410:

You are correct - I was looking in the wrong place. Even so, I prefer setting 
rxhdr_size in the case branches, and not adjust one preset earlier.

Larry