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    SubjectRe: [PATCH] led: simplify led_trigger_register_simple
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    On Thu, 2008-11-20 at 16:14 +0200, Felipe Balbi wrote:
    > > In answer to your question about kfree, I agree it needs to be called
    > > upon error. The callers should just be calling
    > > led_trigger_unregister_simple() in their failure paths though which
    > > should take care of all problems? I know we used to register the simple
    > > triggers late in paths so no error handling was needed to keep the code
    > > simple and minimise the LED triggers impact on those systems.
    >
    > Well, led_trigger_register_simple() doesn't return anything. Imagine
    > led_trigger_register_simple() fails, but the driver author decides
    > it's not a failure if, let's say, a led doesn't turn on when we insert
    > a mmc card to the slot since it doesn't change functionality.
    >
    > Now, imagine the user notes the led is not turning on and decides to
    > unload and reload the module to try again. Once again the led doesn't go
    > on. If the user keeps trying, it's quite a dangerous memory leak, right
    > ?

    So we have the module loading and one of two things happens:

    led_trigger_register_simple() succeeds
    led_trigger_register_simple() fails (probably from kmalloc failure)

    The module doesn't know or care which happened. When the module unloads
    it calls led_trigger_unregister_simple() which will free the memory in
    the success case and do nothing in the case where it had failed.

    So there is no memory leak?

    Cheers,

    Richard



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