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    Subject[PATCH 4.19 082/116] dmaengine: qcom_hidma: comment platform_driver_register call
    Date
    From: Phillip Potter <phil@philpotter.co.uk>

    [ Upstream commit 4df2a8b0ad634d98a67e540a4e18a60f943e7d9f ]

    Place a comment in hidma_mgmt_init explaining why success must
    currently be assumed, due to the cleanup issue that would need to
    be considered were this module ever to be unloadable or were this
    platform_driver_register call ever to fail.

    Acked-By: Vinod Koul <vkoul@kernel.org>
    Acked-By: Sinan Kaya <okaya@kernel.org>
    Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
    Link: https://lore.kernel.org/r/20210503115736.2104747-52-gregkh@linuxfoundation.org
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/dma/qcom/hidma_mgmt.c | 14 ++++++++++++++
    1 file changed, 14 insertions(+)

    diff --git a/drivers/dma/qcom/hidma_mgmt.c b/drivers/dma/qcom/hidma_mgmt.c
    index d64edeb6771a..f9640e37b139 100644
    --- a/drivers/dma/qcom/hidma_mgmt.c
    +++ b/drivers/dma/qcom/hidma_mgmt.c
    @@ -423,6 +423,20 @@ static int __init hidma_mgmt_init(void)
    hidma_mgmt_of_populate_channels(child);
    }
    #endif
    + /*
    + * We do not check for return value here, as it is assumed that
    + * platform_driver_register must not fail. The reason for this is that
    + * the (potential) hidma_mgmt_of_populate_channels calls above are not
    + * cleaned up if it does fail, and to do this work is quite
    + * complicated. In particular, various calls of of_address_to_resource,
    + * of_irq_to_resource, platform_device_register_full, of_dma_configure,
    + * and of_msi_configure which then call other functions and so on, must
    + * be cleaned up - this is not a trivial exercise.
    + *
    + * Currently, this module is not intended to be unloaded, and there is
    + * no module_exit function defined which does the needed cleanup. For
    + * this reason, we have to assume success here.
    + */
    platform_driver_register(&hidma_mgmt_driver);

    return 0;
    --
    2.30.2


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