Date: Mon, 29 Dec 2008 06:30:07 GMT From: Sean Bruno <sbruno@miralink.com> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/118093: firewire bus reset hogs CPU, causing data to be lost Message-ID: <200812290630.mBT6U7vj078851@freefall.freebsd.org>
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The following reply was made to PR kern/118093; it has been noted by GNATS. From: Sean Bruno <sbruno@miralink.com> To: Dieter <freebsd@sopwith.solgatos.com> Cc: freebsd-firewire@freebsd.org, bug-followup@freebsd.org Subject: Re: kern/118093: firewire bus reset hogs CPU, causing data to be lost Date: Sun, 28 Dec 2008 22:22:26 -0800 Dieter wrote: >>> >>> >>> >> I believe that the spl() calls are just left there as a hint where >> locking should be. >> >> As far as I understand, we need to pay attention to the mutex locks. >> > > I'll rephrase my question. In the old days, locking was done with spl. > The new way is with mutex. But with the spl calls being replaced with > noops, and as far as I can tell the driver is not using mutex, there > doesn't appear to be any locking. So the driver can step on itself. > > Well, there is locking around a couple of mutex's via FW_GLOCK(). It appears that the locking is not robust, and that is one of the issues that I am looking into right now. > >>>> is to real behavior, but /var/log/messages has a tendency to get garbled >>>> like this: >>>> >>>> Dec 22 16:00:18 home-test kernel: fwohci1: Initiate bus reset >>>> Dec 22 16:00:18 home-test kernel: fwohci1: BUS reset >>>> Dec 22 16:00:18 home-test kernel: fwohci1: node_id=0xc800ffc0, gen=8, >>>> CYCLEMASTER mode >>>> Dec 22 16:00:18 home-test kernel: firewi >>>> Dec 22 16:00:18 home-test kernel: re1: >>>> Dec 22 16:00:18 home-test kernel: 1 n >>>> Dec 22 16:00:18 home-test kernel: odes >>>> Dec 22 16:00:18 home-test kernel: , ma >>>> Dec 22 16:00:18 home-test kernel: xhop >>>> Dec 22 16:00:18 home-test kernel: <= >>>> Dec 22 16:00:18 home-test kernel: 0, c >>>> Dec 22 16:00:18 home-test kernel: able >>>> >>>> >>> Do the lines get folded on the console, or only in /var/log/messages? >>> >>> >> As far as I can see, the console messages are fine. It's only the >> messages that get >> garbled. >> > > Perhaps an artifact of syslogd? > I doubt it. I'm working on a patch that improves the locking a bit and does some other "gross" things to try and keep things from flying apart. I've SEEN this behaviour in my implementations with sbp_targ and couldn't pin it down. Scott Long gave me a couple of pointers this evening, but I'm still working on locking down the taskqueues and some of the callback_handlers. There are some bad things going on specifically during initialization that are pre-empting normal operation. Sean
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