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    SubjectRe: module load/unload race protection?
    On Sat, Apr 14, 2001 at 12:26:40PM +0200, Mikael Pettersson wrote:
    > Does the kernel's module loader (kernel/module.c, not kmod)
    > protect adequately against concurrent load/load or load/unload
    > requests? The question applies to both 2.2 and 2.4 kernels.
    > I'm trying to track down a problem where a user using a
    > RedHat 2.2.17-14 SMP kernel managed to trigger a situation where
    > a driver module had been unloaded while still being in use
    > (as in "the kernel has pointers into it", not USE_COUNT != 0).
    > I'm reviewing the driver's internal INC/DEC_USE_COUNT usage,
    > but so far I've not found any obvious errors.
    > /Mikael

    There are race conditions while module unloading, present in both 2.2 and 2.4
    kernels. Efforts are being made in handling these races by using
    read-copy-update mechanism (
    and by using synchronize_kernel() (from Rusty Russell, Keith Owens).


    Maneesh Soni <>
    IBM Linux Technology Center,
    IBM Software Lab, Bangalore, India
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