linux-kernel - Re: [PATCH v1] PCI: starfive: Fix kmemleak in StarFive PCIe driver's IRQ handling

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Message-ID: <20250224080129.zm7fvxermgeyycav@thinkpad>
Date: Mon, 24 Feb 2025 13:31:29 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Anand Moon <linux.amoon@...il.com>
Cc: Kevin Xie <kevin.xie@...rfivetech.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Conor Dooley <conor.dooley@...rochip.com>,
	Minda Chen <minda.chen@...rfivetech.com>,
	"open list:PCIE DRIVER FOR STARFIVE JH71x0" <linux-pci@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] PCI: starfive: Fix kmemleak in StarFive PCIe driver's
 IRQ handling

On Thu, Feb 20, 2025 at 03:53:31PM +0530, Anand Moon wrote:

[...]

> Following the change fix this warning in a kernel memory leak.
> Would you happen to have any comments on these changes?
> 
> diff --git a/drivers/pci/controller/plda/pcie-plda-host.c
> b/drivers/pci/controller/plda/pcie-plda-host.c
> index 4153214ca410..5a72a5a33074 100644
> --- a/drivers/pci/controller/plda/pcie-plda-host.c
> +++ b/drivers/pci/controller/plda/pcie-plda-host.c
> @@ -280,11 +280,6 @@ static u32 plda_get_events(struct plda_pcie_rp *port)
>         return events;
>  }
> 
> -static irqreturn_t plda_event_handler(int irq, void *dev_id)
> -{
> -       return IRQ_HANDLED;
> -}
> -
>  static void plda_handle_event(struct irq_desc *desc)
>  {
>         struct plda_pcie_rp *port = irq_desc_get_handler_data(desc);
> @@ -454,13 +449,10 @@ int plda_init_interrupts(struct platform_device *pdev,
> 
>                 if (event->request_event_irq)
>                         ret = event->request_event_irq(port, event_irq, i);
> -               else
> -                       ret = devm_request_irq(dev, event_irq,
> -                                              plda_event_handler,
> -                                              0, NULL, port);

This change is not related to the memleak. But I'd like to have it in a separate
patch since this code is absolutely not required, rather pointless.

> 
>                 if (ret) {
>                         dev_err(dev, "failed to request IRQ %d\n", event_irq);
> +                       irq_dispose_mapping(event_irq);

So the issue overall is that the 'devm_request_irq' fails on your platform
because the interrupts are not defined in DT and then the IRQ is not disposed in
the error path?

In that case, none of the error paths below for_each_set_bit() loop is disposing
the IRQs. Also, calling 'irq_dispose_mapping()' only once is not going to
dispose all mappings that were created before in the loop.

- Mani

-- 
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