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    SubjectRe: [bug, 2.6.26-rc4/rc5] sporadic bootup crashes in blk_lookup_devt()/prepare_namespace()
    On Mon, 9 Jun 2008 09:15:40 -0700 (PDT),
    Linus Torvalds <> wrote:

    > And this is all still ignoring the locking issue, of course. It would be
    > trivial to just remove the block_class_lock, and change
    > mutex_[un]lock(&block_class_lock);
    > into
    > down|up(&block_class.sem);
    > except for _one_ case, which is
    > bdev_map = kobj_map_init(base_probe, &block_class_lock);
    > which really wants a mutex, not a sempahore.
    > So to fix that, we'd need to make the class->sem be a mutex, and pass that
    > in. Which is probably a good change too, but makes the whole thing much
    > bigger.

    The driver core changes in -next convert class->sem to
    class->p->class_mutex, which makes it non-accessible to drivers.
    Most of the locking is easily done through converting to the class
    iterator functions, but there are some cases where this is not going to

    - The {register,unregister}_blkdev() functions, which don't directly
    involve the class.
    - The iterators for /proc/partitions, which take the lock in
    part_start() and give it up again in part_stop().

    Maybe we need a possibilty for a driver to lock a class from outside?

     \ /
      Last update: 2008-06-09 19:19    [W:0.031 / U:0.248 seconds]
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