On Tue, 01 Oct 2024 12:54:30 +0100, Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx> wrote: > > 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. That I would agree. > 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? My general approach is that these scripts are not a substitute for reasoning, and in this instance, the advise seems pretty misplaced. I would suggest you add a comment to keep the next script kiddie at bay. M. -- Without deviation from the norm, progress is not possible.
