Date: Sun, 5 Jan 2014 09:44:14 +0100 From: Michael Tuexen <Michael.Tuexen@lurchi.franken.de> To: Adrian Chadd <adrian@freebsd.org> Cc: Yong-Hyeon Pyun <pyunyh@gmail.com>, John Baldwin <jhb@freebsd.org>, FreeBSD Net <freebsd-net@freebsd.org>, John-Mark Gurney <jmg@funkthat.com>, Jack Vogel <jfvogel@gmail.com>, Jack F Vogel <jfv@freebsd.org> Subject: Re: A small fix for if_em.c, if_igb.c, if_ixgbe.c Message-ID: <B14A7230-8984-486A-8027-22CAB3BD0717@lurchi.franken.de> In-Reply-To: <CAJ-VmonFBMSKJ6fbZhWRWrBbY9wRtKYMGNpK5wLsPUEeh8eC7A@mail.gmail.com> References: <521B9C2A-EECC-4412-9F68-2235320EF324@lurchi.franken.de> <201312131326.28952.jhb@freebsd.org> <CAJ-VmokoujrNBO21oOdTuzncamS%2BtAjCUKjt4ywJaySL2rAo6g@mail.gmail.com> <201312131717.10863.jhb@freebsd.org> <CAJ-VmomXPiWbYztWxTDSRJkPcee%2B3pQmUHHk=2U3HG72bcKoyw@mail.gmail.com> <0BC9D25E-639A-4305-A51A-222AE645152C@lurchi.franken.de> <CAJ-VmomHnQVP9s3EXuNOVwGaB-JiT_imAqzYT_U6PETvR6KMDw@mail.gmail.com> <FBA7A484-BFA6-4A9E-B910-5E8CA799DC45@lurchi.franken.de> <CAJ-VmokGnzscOuPRQ3wSom0mZ0MFBKRfiNJtHOu4Lw8sb7g3-A@mail.gmail.com> <CAJ-VmonFBMSKJ6fbZhWRWrBbY9wRtKYMGNpK5wLsPUEeh8eC7A@mail.gmail.com>
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On Jan 4, 2014, at 11:45 PM, Adrian Chadd <adrian@freebsd.org> wrote: > hi, > > Happy New Year all. > > If noone objects, I'm going to commit Michael's patch to -HEAD in the > next couple of days, with some extra comments explaining why things > are the way they are. Hi Adrian, just use the last version of the patch, the one from December 6th... Best regards Michael > > We can then flesh out the comments and API documentation about this stuff. > > Thanks! > > > > -a > > > On 16 December 2013 19:25, Adrian Chadd <adrian@freebsd.org> wrote: >> On 16 December 2013 13:04, Michael Tuexen >> <Michael.Tuexen@lurchi.franken.de> wrote: >>> On Dec 16, 2013, at 9:15 PM, Adrian Chadd <adrian@freebsd.org> wrote: >>> >>>> On 16 December 2013 12:06, Michael Tuexen >>>> <Michael.Tuexen@lurchi.franken.de> wrote: >>>> >>>>>> i agree. if_transmit() should return 0 only if: >>>>>> >>>>>> * the driver queued it internally and intends to try transmitting it later; >>>>>> * the driver directly dispatched the frame to the hardware. >>>>>> >>>>>> If it failed to do either of the above, it should return an error. >>>>>> >>>>>> How's that sound? >>>>> That sounds good. However, The transport layer is interested in the case >>>>> where if_transmit() returns a non-zero value. >>>>> Does your statement imply: >>>>> if_transmit() returns a non-zero value only if the packet will not >>>>> make it on the wire (for example, it failed to queue it). >>>> >>>> If there's a queuing layer in the middle then we can't know that for >>>> certain. If the driver can't transmit the frame (eg it fails because >>>> of collisions, for example) then again, we can't know that for >>>> certain. >>>> >>>> What we can only know is that it was either queued and may or may not >>>> make it on the wire, or it wasn't queued/transmitted and it definitely >>>> _won't_ make it on the wire. >>> Correct. And I'm only interested in the "it wasn't queued/transmitted >>> and it definitely _won't_ make it on the wire." part. >>> So I would need something like >>> >>> if_transmit() returns an error only if it wasn't queued/transmitted >>> and it definitely _won't_ make it on the wire. >>> >>> Acceptable for you? >> >> Sounds like the same thing to me, so yes. :) >> >> >> >> -a >
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