From: Marc Kleine-Budde <m...@pengutronix.de>
Date: Mon, 6 Feb 2017 17:43:43 +0100
> On 02/06/2017 05:12 PM, David Miller wrote:
>> From: Marc Kleine-Budde <m...@pengutronix.de>
>> Date: Mon, 6 Feb 2017 15:50:48 +0100
>>
>>> this is a pull request of 16 patches for net-next/master.
>>>
>>> The first two patches by David Jander and me add the rx-offload
>>> framework for CAN devices to the kernel. The remaining 14 patches
>>> convert the flexcan driver to make use of it.
>>
>> Pulled, but I wonder if your comparisons does the right thing when the
>> counters overflow.
>>
>> I think you need to do the same thing we do for TCP sequence number
>> comparisons and code it like:
>>
>> static inline bool before(__u32 seq1, __u32 seq2)
>> {
>> return (__s32)(seq1-seq2) < 0;
>> }
>
> Yes, I think it's basically the same as the TCP sequence number code,
> but obviously less readable.
>
>> static int can_rx_offload_compare(struct sk_buff *a, struct sk_buff *b)
>> {
>> const struct can_rx_offload_cb *cb_a, *cb_b;
>>
>> cb_a = can_rx_offload_get_cb(a);
>> cb_b = can_rx_offload_get_cb(b);
>>
>> /* Substract two u32 and return result as int, to keep
>> * difference steady around the u32 overflow.
>> */
>> return cb_b->timestamp - cb_a->timestamp;
>> }
>
> This does the "(__s32)(seq1-seq2)"
...
>
> And here the "return ... < 0;"
Sure but what about these "can_rx_offload_le()" comparisons?
