[lkml]   [2006]   [Nov]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: deadlock in "modprobe -r ohci1394" shortly after "modprobe ohci1394"
    Alan Stern wrote:
    > Wait a minute. Above you agreed that the problem was caused by knodemgrd
    > attempting to rescan the host's _parent_. So which is the focus of the
    > deadlock: the host or its parent?

    The parent of the hpsb_host.

    ohci1394 works on a pci_dev which contains a dev, let's call it A.

    ieee1394 has a hpsb_host which contains a dev, let's call it B. B's
    parent is A. Then there is one or more node_entry with dev C whose
    parent is B, end unit_directory with dev D whose parent is C.

    The bus of devices B, C, D is set to be ieee1394_bus_type, and that's
    what knodemgrd is scanning.

    knodemgrd blocks on the semaphore of the parent of B because
    driver_detach took the semaphore of A (and of the parent of A if there
    is one).

    > If I understand all this, you've got an hpsb_host, directly below which
    > are one or more node_entry's, below each of which may be some
    > unit_directory's. Right?


    > But how is this relevant if the problem is caused by knodemgrd trying to
    > rescan the hpsb_host's parent?

    It's rescanning just the hpsb_host, but you surely got the picture now.

    > Is the problem caused by the fact that some of these struct device's
    > aren't bound to a driver? Remember, bus_rescan_devices() will skip over
    > anything that already has a driver. Could you solve your problem by
    > adding a do_nothing driver that would bind to these otherwise unused
    > devices?

    Excellently, that's what I will try in a minute. It is surely intended
    that the hpsb_host can get a driver bound too, but as I mentioned, we
    don't have a driver which needs this capability and I don't foresee any
    such driver.

    Thanks for the directions.
    Stefan Richter
    -=====-=-==- =-== =-=--
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2006-11-20 21:49    [W:0.021 / U:8.952 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site