>> >> [1] >> Both sctp_outq_flush_rtx and sctp_packet_transmit can ONLY >> return one error (-ENOMEM), as sctp_outq_flush_rtx also calls >> sctp_packet_transmit. > > What is the effect of the error? > If it is 'just' equivalent to a lost ethernet packet (and the skb (etc) > is freed) then the protocol will recover. > If it is anything else then the error path is probably wrong. This err returns back to sctp_sendmsg, there sctp will abort asoc. in this function, sctp tries to do 3 things: 1. flush rtx queue 2. transmit the packet of current transport 3. flush all the transports. Now sctp would do them one by one, even if one of them returns err. > > Also after one error is it actually worth trying to send anything else > at all? ISTM that the code should either: yeah, that's the problem. the "sctp_flush_out:" code tries to force clear all the transport before returning even if there're errors already. > 1) wait for resources and retry. > 2) discard the entire queue (freeing resource) and hope the protocol > timers will recover. It's a different process, will think about it. > >> [2] >> It's the original codes that it doesn't return immediately when >> sctp_outq_flush_rtx returns error. I guess it just doesn't want >> to stop flushing out transport_list only because it fail to flush >> rtx. >> even sctp_packet_transmit_chunk in sctp_outq_flush also just >> put the error into sk->sk_err, instread of returning immediately. >> >> So we cannot return the err at the first failure as [2], the error >> here is always -ENOMEM as [1]. >> I think to return the last error here is ok, at least not dangerous, >> can also fix the issue "a success return may hide an error" with >> clear codes. :) > > Which code looks at sk->sk_err? > It doesn't look right to be setting an error code on the socket due > a transmit packet discard. I guess sctp_packet_transmit_chunk's return value is used for 'status' (like PMTU_FULL,RWND_FUL... ), that's why err was put into sk->sk_err. This err is supposed to be checked in sctp_sendmsg, but there sctp_error check sk->sk_err only when err == -EPIPE. yes, we need to fix this, thanks. -- 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
