On 7/25/12, Neil Horman <nhorman@xxxxxxxxxxxxx> wrote: > On Wed, Jul 25, 2012 at 05:22:19PM +0800, Xufeng Zhang wrote: >> On 7/25/12, Xufeng Zhang <xufengzhang.main@xxxxxxxxx> wrote: >> > On 7/25/12, Vlad Yasevich <vyasevich@xxxxxxxxx> wrote: >> >> >> >> Actually not true. AUTH can be before SACK. So can any addip chunks >> >> that >> >> aid in locating an association. >> >> >> >> Now AUTH isn't a big issue since its autogenerated to the packet but >> >> ADDIP >> >> is since it could be queued up for retransmission. >> >> >> >> There could be other extensions as well. It really needs to be done >> >> either >> >> through side effects or making error chunks go at the end of other >> >> control >> >> chunks. Need to audit the spec to see if that's ok. >> > You are right, I just found SHUTDOWN chunks are also before SACK based >> > on >> > your commit "[SCTP]: Fix SACK sequence during shutdown". >> > Maybe the only solution is to do some work on side effects just as you >> > said. >> > Thanks for your explanation! >> >> And after take a moment to look into the relative codes, I think we >> can implement it >> by below way: >> 1). Add a flag(isi_err_needed) in the embedded struct peer of struct >> struct sctp_association >> just like sack_needed flag. >> 2). When "invalid stream identifier" ERROR happens in sctp_eat_data() >> function, we just >> set isi_err_needed flag and don't create ERROR chunk and also don't >> insert SCTP_CMD_REPLY command. >> 3). In sctp_gen_sack() function, we create ERROR chunk and also insert >> SCTP_CMD_REPLY command if isi_err_needed flag is set. >> >> Is this way proper? >> > That would probably work yes. Another way might just be to do some > re-ordering > in sctp_outq_flush. Before processing the control chunk list, scan it, > and: > 1) move all error chunks to the head of the list > 2) move all sack chunks to the head of the list > 3) move all shutdown chunks to the head of the list > > You can do that in a single iteration of the list if you use a few on-stack > lists and list_splice Thank you very much for your suggestion! I'll compare it with side effects modification and make a decision. Thanks, Xufeng Zhang > > Neil > >> >> Thanks, >> Xufeng Zhang >> > >> > >> > >> > Thanks, >> > Xufeng Zhang >> >> >> >> -vlad >> >>> >> >>>Thanks, >> >>>Xufeng Zhang >> >>>> >> >>>> -vlad >> >> >> >> >> >> -- >> >> Sent from my Android phone with SkitMail. Please excuse my brevity. >> >> >> > >> > -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
