On Mon, 20 Jul 2015, Alex Smith wrote: > 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. Great. Thanks. julia -- 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
