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    SubjectRe: [linux-usb-devel] [PATCH] back out sysfs reference count change
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    On Wed, 2004-03-31 at 09:55, Greg KH wrote:
    > Hi,
    >
    > The patch below backs out Maneesh's sysfs patch that was recently added
    > to the kernel. In its defense, the original patch did solve some fixes
    > that could be duplicated on SMP machines, but the side affect of the
    > patch caused lots of problems. Basically it caused kobjects to get
    > their references incremented when files that are not present in the
    > kobject are asked for (udev can easily trigger this when it looks for
    > files call "dev" in directories that do not have that file). This can
    > cause easy oopses when the VFS later ages out those old dentries and the
    > kobject has its reference finally released (usually after the module
    > that the kobject lived in was removed.)

    I think that the bug in the first place is to have an existing
    kobject that didn't bump the module ref count.

    If a kobject exists that have a pointer to the module code (the
    release function), it _MUST_ have bumped the module ref count,
    that's the whole point of the module reference count.

    If rmmod blocks forever because that kobject has a stale reference,
    that's a different problem, but khubd should not be involved in
    that process and should definitely not be blocked and not wait for
    the kobject to go away.

    Ben.


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