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    SubjectRe: [PATCH 2/3] uml: fix proc-vs-interrupt context spinlock deadlock
    Jeff Dike <> ha scritto: 

    > On Tue, Aug 08, 2006 at 12:59:05PM +0200, Paolo Giarrusso wrote:
    > > I could be wrong, but I trust that thanks to deep and good work
    > by
    > > who designed locking in the network layer, this patch is correct.
    > And
    > > indeed I addressed your issues below.
    > OK, but there will need to be comments explaining why it is OK that
    > this data only looks half-locked.

    Guess I'll put it in Documentation and reference it.

    > The locking, as it stands, looks consistent and conservative.
    Yes, it is.
    > However, there are some places where critical sections are too big
    > and
    > the locking should be narrowed.

    Yes, in particular we cannot hold a spinlock for the whole _open
    since it must call sleeping functions.

    > > This is also true of char/block devices (you don't need to lock
    > > against write/read in open/close; UBD doesn't know that but I
    > have
    > > unfinished patches for it), but there it's simpler: if userspace
    > you
    > > call close while a read is executing, thanks to refcounting
    > (sys_read
    > > does fget) the ->close (or ->release) is only called after the
    > end of
    > > ->read.
    > In my current patchset, there is a per-queue lock which is mostly
    > managed by the block layer.

    I'll try then to finish the patches soon and merge them; the main
    problem is splitting (including the use of different locks) normal
    locking from our peculiar locking of _open/_close against mconsole

    Chiacchiera con i tuoi amici in tempo reale!*
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      Last update: 2006-08-09 16:49    [W:0.020 / U:40.932 seconds]
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