Re: [PATCH 4/4] drivers/pci/hotplug: Support surprise hotplug

[Bjorn Helgaas <helgaas@kernel.org>]

On Mon, Sep 26, 2016 at 11:08:02PM +1000, Gavin Shan wrote:
> On Wed, Sep 21, 2016 at 11:57:03AM -0500, Bjorn Helgaas wrote:
> >Hi Gavin,
> >
> >You don't need my ack for any of these, and I assume you'll merge them
> >through the powerpc tree.
> >
> >Minor comments below, feel free to ignore them.
> >
> >On Wed, Sep 21, 2016 at 10:15:30PM +1000, Gavin Shan wrote:
> >> ...
> >> @@ -536,9 +565,16 @@ static struct pnv_php_slot *pnv_php_alloc_slot(struct device_node *dn)
> >>  	if (unlikely(!php_slot))
> >>  		return NULL;
> >>  
> >> +	php_slot->event = kzalloc(sizeof(struct pnv_php_event), GFP_KERNEL);
> >> +	if (unlikely(!php_slot->event)) {
> >> +		kfree(php_slot);
> >> +		return NULL;
> >> +	}
> >
> >Since you *always* allocate the event when allocating the php_slot,
> >making the event a member of php_slot (instead of keeping a pointer to
> >it) would simplify your memory management a bit.
> >
> >It seems to be the style in this file to use "unlikely" liberally, but
> >I really doubt there's any performance consideration in this code.  To
> >me it adds more clutter than usefulness.
> >
> >> +static irqreturn_t pnv_php_interrupt(int irq, void *data)
> >> +{
> >> +	struct pnv_php_slot *php_slot = data;
> >> +	struct pci_dev *pchild, *pdev = php_slot->pdev;
> >> +	struct eeh_dev *edev;
> >> +	struct eeh_pe *pe;
> >> +	struct pnv_php_event *event;
> >> +	u16 sts, lsts;
> >> +	u8 presence;
> >> +	bool added;
> >> +	unsigned long flags;
> >> +	int ret;
> >> +
> >> +	pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &sts);
> >> +	sts &= (PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC);
> >> +	pcie_capability_write_word(pdev, PCI_EXP_SLTSTA, sts);
> >
> >I didn't realize that this is some sort of hybrid of native PCIe
> >hotplug and PowerNV-specific stuff.  Wonder if there's any opportunity
> >to combine with or leverage pciehp.  That seems pretty blue-sky
> >though, since there's so much PowerNV special sauce here.
> >
> 
> Bjorn, thanks a lot for your comments. All comments except last one
> (leverage pciehp) are covered in v2 which wasn't copied to linux-pci@
> list to avoid unnecessary traffic. Yeah, the driver is too much PowerNV
> platform specific things, which makes it hard to be built on top of
> pciehp.

Sounds good, thanks!