Messages in this thread | | | Date | Thu, 9 Nov 2023 12:33:25 +0100 | Subject | Re: [RFC PATCH] fpga: remove module reference counting from core components | From | Marco Pagani <> |
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On 2023-11-08 17:20, Greg Kroah-Hartman wrote: > On Wed, Nov 08, 2023 at 11:52:52PM +0800, Xu Yilun wrote: >>>>> >>>>> In fpga_region_get() / fpga_region_put(): call get_device() before >>>>> acquiring the mutex and put_device() after having released the mutex >>>>> to avoid races. > > Why do you need another reference count with a lock? You already have > that with the calls to get/put_device(). >
My understanding is that the lock is there not for reference counting but to prevent concurrent reprogramming of the region by in-kernel API consumers.
>>>> Could you help elaborate more about the race? >>>> >>> >>> I accidentally misused the word race. My concern was that memory might >>> be released after the last put_device(), causing mutex_unlock() to be >>> called on a mutex that does not exist anymore. It should not happen >>> for the moment since the region does not use devres, but I think it >>> still makes the code more brittle. >> >> It makes sense. >>
Thanks, Marco
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