linux-kernel - Re: [PATCH] PCI: tegra: Fix runtime PM imbalance in pex_ep_event_pex_rst

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Message-ID: <YG8AcAJKVC1kFe0n@orome.fritz.box>
Date:   Thu, 8 Apr 2021 15:09:04 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Jon Hunter <jonathanh@...dia.com>
Cc:     Dinghao Liu <dinghao.liu@....edu.cn>, kjlu@....edu,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Vidya Sagar <vidyas@...dia.com>,
        Jingoo Han <jingoohan1@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-pci@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: tegra: Fix runtime PM imbalance in
 pex_ep_event_pex_rst_deassert

On Thu, Apr 08, 2021 at 01:34:37PM +0100, Jon Hunter wrote:
> 
> On 08/04/2021 08:26, Dinghao Liu wrote:
> > pm_runtime_get_sync() will increase the runtime PM counter
> > even it returns an error. Thus a pairing decrement is needed
> > to prevent refcount leak. Fix this by replacing this API with
> > pm_runtime_resume_and_get(), which will not change the runtime
> > PM counter on error.
> > 
> > Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
> > ---
> >  drivers/pci/controller/dwc/pcie-tegra194.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
> > index 6fa216e52d14..0e94190ca4e8 100644
> > --- a/drivers/pci/controller/dwc/pcie-tegra194.c
> > +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
> > @@ -1645,7 +1645,7 @@ static void pex_ep_event_pex_rst_deassert(struct tegra_pcie_dw *pcie)
> >  	if (pcie->ep_state == EP_STATE_ENABLED)
> >  		return;
> >  
> > -	ret = pm_runtime_get_sync(dev);
> > +	ret = pm_runtime_resume_and_get(dev);
> >  	if (ret < 0) {
> >  		dev_err(dev, "Failed to get runtime sync for PCIe dev: %d\n",
> >  			ret);
> > 
> 
> There are two places in the driver where pm_runtime_get_sync() is called.

It looks like the second callsite has the proper cleanup code. Although
it might be nice to use pm_runtime_resume_and_get() there as well, and
adjust the cleanup path, to make this consistent.

In any case, this looks good to me:

Acked-by: Thierry Reding <treding@...dia.com>

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