Messages in this thread | | | Date | Mon, 22 Jun 2015 17:09:29 +0200 | From | Oliver Hartkopp <> | Subject | Re: [PATCH - regression 4.1-rc8] can: fix loss of CAN frames in raw_rcv |
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On 22.06.2015 13:49, Manfred Schlaegl wrote: > On 2015-06-22 12:34, Oliver Hartkopp wrote: >> On 22.06.2015 12:10, Manfred Schlaegl wrote: >>> Hypothetical example: If timestamping is enabled by the user and there is a significant delay between allocation and delivery of a skb (early allocation in driver or something) the timestamp does not reflect the reception time anymore. >> >> The change only affects CAN skbs. >> These skbs are allocated at CAN frame reception time, filled with content and then sent to the network layer. >> >> AFAICS the timestamp becomes more precise for CAN related skbs. >> I did not see any case of 'early allocation' in linux/drivers/net/can, did you? > > No, I also did not find this case in current driver implementations -- because of that I gave the hypothetical example. > I just was worried about that this may be a potential latent issue for future driver implementations and wanted to indicate this. > > But I trust your expertise, so if you are fine with it, I'm too. ;-)
I don't claim to be 'an expert' :-)
But our usual use-case is CAN logging which enables the timestamping on all CAN interfaces anyway - without any problems.
As the timestamp is calculated only once this patch moves the timestamp creation closer to the CAN frame arrival time - so latency finally decreases.
Best regards, Oliver
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