Date: Fri, 29 Jun 2007 20:30:05 +0900 From: "Hidetoshi Shimokawa" <simokawa@FreeBSD.ORG> To: "Doug Rabson" <dfr@rabson.org> Cc: freebsd-firewire@freebsd.org Subject: Re: [CFT] MPSAFE firewire Message-ID: <626eb4530706290430we45e352xf27592d7eac99cf8@mail.gmail.com> In-Reply-To: <200706291024.56591.dfr@rabson.org> References: <626eb4530706060746u44226cfajcedb3e169996a51a@mail.gmail.com> <200706291024.56591.dfr@rabson.org>
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All the access to the RX DMA is dispatched from a taskqueue, so that they are serialized and they don't need a lock. As far as I understand, the code paths you concern are running in a single thread(fw_taskq). Correct me, if I'm wrong. FWXFERQ_HANDLER is currently used only by fwe and fwip. For DV streams, since the queue is access by userland threads, we need a lock. On 6/29/07, Doug Rabson <dfr@rabson.org> wrote: > > > On Wednesday 06 June 2007, Hidetoshi Shimokawa wrote: > > > I have just committed MPSAFE(Giant free) firewire driver to -current. > > > If you have any problem, please let me know. > > > > I've been looking through the code and I have a few questions. > > > > In fwohci_rbuf_update(), you only call FW_GLOCK() if the FWXFERQ_HANDLER > flag is zero. Doesn't this cause problems for the if_fwip driver (the only > one to set this flag)? As far as I can see, if this flag is set, there is no > mutex protection for any of the dma queues. Shouln't FW_GLOCK be used > always? Also, additional protection is needed in fwip_stream_input where it > manipulates the stvalid and stfree queues. > > > > I'm a bit confused about the async read path too. I'm looking at the code in > fwohci_arcv() and I can't see any mutex protection in this function while it > manipulates the buffers. Is this correct? I see some fossil use of splfw() > here which is why I ask. Following the input path back to the fwip driver > again, I can't see any mutex protection for the driver's unicast packet > input queues. > > > > The last possible problem I noticed reading through the code is that there > is no mutex protection of the fragmented packet reassembly queues in > firewire_input_fragment. Perhaps the fw_com structure should have a mutex > pointer in it which can be initialised to the if_fwip code's mutex and used > in this case. > > -- /\ Hidetoshi Shimokawa \/ simokawa@FreeBSD.ORG
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