Hi Marc, thank you for your reply. > From: Marc Zyngier <maz@xxxxxxxxxx> > Sent: Monday, September 30, 2024 8:15 PM > To: Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx> > Subject: Re: [PATCH] irqchip/renesas-rzg2l: Fix missing put_device > > On Mon, 30 Sep 2024 17:36:20 +0100, > Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx> wrote: > > > > Hi Marc, > > > > Thanks for your feedback. > > > > > From: Marc Zyngier <maz@xxxxxxxxxx> > > > Sent: Monday, September 30, 2024 4:50 PM > > > To: Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx> > > > Subject: Re: [PATCH] irqchip/renesas-rzg2l: Fix missing put_device > > > > > > On Mon, 30 Sep 2024 15:55:39 +0100, > > > Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx> wrote: > > > > > > > > rzg2l_irqc_common_init calls of_find_device_by_node, but the > > > > corresponding put_device call is missing. > > > > > > > > Make sure we call put_device both when failing and when succeeding. > > > > > > What sort of lifetime are you trying to enforce? > > > > Function rzg2l_irqc_common_init uses pdev->dev until its very end. > > My understanding is that we should decrement the reference counter > > once we are fully done with it. Is my understanding correct? > > "done with it" is what scares me. Specially when I see code like this: > > rzg2l_irqc_data = devm_kzalloc(&pdev->dev, sizeof(*rzg2l_irqc_data), GFP_KERNEL); > if (!rzg2l_irqc_data) > return -ENOMEM; > > rzg2l_irqc_data->irqchip = irq_chip; > > rzg2l_irqc_data->base = devm_of_iomap(&pdev->dev, pdev->dev.of_node, 0, NULL); > if (IS_ERR(rzg2l_irqc_data->base)) > return PTR_ERR(rzg2l_irqc_data->base); > > If you drop the reference on the device, you are allowing it to be removed, and everything the driver > cares about to disappear behind its back. Thanks for the explanation. I think this means that we don't need to put the device on the successful path, but we still need to put the device on the error path. If I take out the put_device for the successful path, and I run make coccicheck, I get the below: drivers/irqchip/irq-renesas-rzg2l.c:601:1-7: ERROR: missing put_device; call of_find_device_by_node on line 538, but without a corresponding object release within this function. Can I just ignore it? Thanks! Kind regards, Fab > > I can't really see how this is safe, because in general, removing an interrupt controller driver from > the system is a pretty bad idea, and I'm worried that's you are implicitly enabling. > > M. > > -- > Without deviation from the norm, progress is not possible.
