Re: [PATCH v2 2/5] PCI: dwc: Check alloc_page() return value

Jisheng Zhang
2020-09-30T01:29:04Z

Hi Marc,

On Tue, 29 Sep 2020 18:29:52 +0100 Marc Zyngier wrote:

>
>
> On 2020-09-24 12:06, Jisheng Zhang wrote:
> > We need to check alloc_page() succeed or not before continuing.
> >
> > Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
> > ---
> > drivers/pci/controller/dwc/pcie-designware-host.c | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c
> > b/drivers/pci/controller/dwc/pcie-designware-host.c
> > index 0a19de946351..9e04e8ef3aa4 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> > @@ -303,6 +303,11 @@ void dw_pcie_msi_init(struct pcie_port *pp)
> > u64 msi_target;
> >
> > pp->msi_page = alloc_page(GFP_KERNEL);
> > + if (!pp->msi_page) {
> > + dev_err(dev, "Failed to alloc MSI page\n");
>
> A failing allocation will already scream, so there is no need to
> add insult to injury.
>
> More importantly, what is this MSI page ever used for? If I remember
> well, this is just a random address that never gets written to.
>
> So why do we allocate a page here? Why do we bother with this DMA
> mapping?
>

Ard and Rob also pointed out that there's no need to allocate a page, instead,
we could use an address in the driver data for MSI address. So I refactored
the patches and verified this solution works fine. Could you please review
the V5?

Thanks