On Wed, 2 Apr 2003, David Brownell wrote: > I got a report of a problem with a high speed CD-ROM that > could be reproduced by a simple loop: > > dd if=/dev/scd0 of=cdrom.iso > cmp /dev/scd0 cdrom.iso > > The failure was reported on 2.4, so I wanted to know if it > showed up on 2.5 too. (Since usb-storage on 2.5 seems to > be more robust.) So I tried it, and it ran fine ... for > about an hour, then the script wedged completely. > > Looking at the system state, there were no requests queued > to the EHCI driver; it wasn't even doing async schedule > processing any more. And the next level up was usb-storage, > which seemed to be waiting for requests too ... meanwhile, > the "dd" was blocked. > > Alt-SysRq-T showed the "dd" blocking in the read; the relevant > bits are appended. Disassembly shows that blk_run_queues+0x146 > is a CLI instruction right after q->unplug_fn(q). > > I'm hunting for suggestions as to what might be wrong, as > well as ideally a fix ... :) This system will be wedged > like this for another hour or two until I reboot it, in > case there's other sleuthing to e suggested. > > - Dave
David: I can't make too much out of the stack traces you included, but I'm puzzled by the usb-storage section. If usb-storage is really just sitting around waiting for a request, then its stack should be pretty short, with almost no function calls. The main routine of the kernel thread is usb_stor_control_thread(), which calls down_interruptible() from its top level while waiting for a request to come. Is it reasonable that all the stuff in your stack dump is just garbage left from the call to down_interruptible()? If nothing better comes up, here's a suggestion. Compile usb-storage with debugging turned on and repeat your test using a serial console (and regular kernel logging turned off!). Of course this will generate lots and lots of logging output but only the last part will be relevant. And we can hope that timing changes caused by the serial output delays will not affect whatever it was you saw. Alan Stern ------------------------------------------------------- This SF.net email is sponsored by: ValueWeb: Dedicated Hosting for just $79/mo with 500 GB of bandwidth! No other company gives more support or power for your dedicated server http://click.atdmt.com/AFF/go/sdnxxaff00300020aff/direct/01/ _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
