On Wed, Apr 22, 2015 at 11:09 AM, Pravin Shelar <pshe...@nicira.com> wrote: > On Wed, Apr 22, 2015 at 10:52 AM, Jesse Gross <je...@nicira.com> wrote: >> On Wed, Apr 22, 2015 at 10:03 AM, Pravin Shelar <pshe...@nicira.com> wrote: >>> On Mon, Apr 20, 2015 at 9:54 PM, Jesse Gross <je...@nicira.com> wrote: >>>> On Mon, Apr 20, 2015 at 7:33 PM, Pravin Shelar <pshe...@nicira.com> wrote: >>>>> On Mon, Apr 20, 2015 at 5:56 PM, Jesse Gross <je...@nicira.com> wrote: >>>>>> On Mon, Apr 20, 2015 at 3:54 PM, Pravin Shelar <pshe...@nicira.com> >>>>>> wrote: >>>>>>> On Mon, Apr 20, 2015 at 3:36 PM, Jesse Gross <je...@nicira.com> wrote: >>>>>>>> On Mon, Apr 20, 2015 at 1:29 PM, Pravin B Shelar <pshe...@nicira.com> >>>>>>>> wrote: >>>>>>>>> diff --git a/datapath/linux/compat/stt.c b/datapath/linux/compat/stt.c >>>>>>>>> new file mode 100644 >>>>>>>>> index 0000000..209bf1a >>>>>>>>> --- /dev/null >>>>>>>>> +++ b/datapath/linux/compat/stt.c >>>>>>>>> +static void update_headers(struct sk_buff *skb, bool head, >>>>>>>>> + unsigned int l4_offset, unsigned int >>>>>>>>> hdr_len, >>>>>>>>> + bool ipv4, u32 tcp_seq) >>>>>>>> [...] >>>>>>>>> + skb->truesize = SKB_TRUESIZE(skb_end_offset(skb)) + >>>>>>>>> skb->data_len; >>>>>>>>> +} >>>>>>>> >>>>>>>> I wonder if there are any possible edge cases with resetting truesize >>>>>>>> where the packet is still in someone's transmit queue (such as if we >>>>>>>> are looping back packet). Do we need to orphan it first? >>>>>>>> >>>>>>> ok, I will orphan it in update_headers. >>>>>> >>>>>> Just to clarify - I was mostly just thinking aloud on orphaning it. >>>>>> I'm not totally sure if that is the right thing to do or if this is >>>>>> the right place to do it. I'm not sure what the conceptual >>>>>> justification would be for it and it could potentially result in the >>>>>> sender's buffers not being properly limited. Perhaps not resetting the >>>>>> truesize is the right thing too... >>>>>> >>>>> I have seen warning msg if we do no keep truesize update along with >>>>> changes to skb. >>>> >>>> Hmm, interesting, what is the warning? I don't think that I have seen >>>> that before. >>> >>> Actually skb_try_coalesce() is updating it correctly. so there no need >>> to change truesize anymore. I will update patch accordingly. >> >> That's much nicer. I also checked and other receive side code (like >> TCP input) doesn't worry about the case where a local sender may still >> be accounting for the packet since any type of loopback device does >> call skb_orphan() in some form. >> >> I hate to bring this up but what about on transmit? In cases where we >> merge or split skbs (skb_try_coalesce() and normalize_frag_list() >> respectively) we do track the truesize for correctly for the result >> but the individual pieces might not have the right destructors or >> might not have their truesize updated for the destructor they do have. > > How about about we update merged skb stats (len, data_len, truesize) > according to *delta_truesize we get from skb_try_coalesce() and then > free the skb?
I think that would work for the skb_try_coalesce() case (although I would only worry about truesize, not the lengths). For normalize_frag_list() I think we would either have to add a destructor or not update truesize. I'm not sure that the condition where we have frag_lists and a destructor actually ever happens in practice though. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
