On 19/07/2015 10:08, Julia Lawall wrote:
The file drivers/dma/dma-jz4780.c has a probe function that sets up irqs
using devm_request_irq. The probe function then ends with:
err_unregister_dev:
dma_async_device_unregister(dd);
err_disable_clk:
clk_disable_unprepare(jzdma->clk);
return ret;
}
The remove function, on the other hand contains:
of_dma_controller_free(pdev->dev.of_node);
devm_free_irq(&pdev->dev, jzdma->irq, jzdma);
dma_async_device_unregister(&jzdma->dma_device);
The need for calling devm_free_irq explicitly would be that it needs to
occur before dma_async_device_unregister, to eg avoid a reference to a
dangling pointer. But devm_free_irq is implicitly called after the call
to dma_async_device_unregister at the end of the probe function. Which
one is correct?
julia
Hi,
I think the explicit devm_free_irq() here is unnecessary, as when remove
is called there should be no remaining users of the DMA controller and
therefore no chance of an IRQ occurring between the controller being
unregistered and an implicit IRQ release afterwards.
I recently sent a series of fixes for this driver, I will send a new
version with a patch to remove the unnecessary free.
Thanks,
Alex
--
To unsubscribe from this list: send the line "unsubscribe dmaengine" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
