2020-11-21 00:14:04

by Kelley, Sean V

[permalink] [raw]
Subject: [PATCH v12 05/15] PCI/ERR: Simplify by using pci_upstream_bridge()

Use pci_upstream_bridge() in place of dev->bus->self. No functional change
intended.

[bhelgaas: split to separate patch]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sean V Kelley <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Acked-by: Jonathan Cameron <[email protected]>
Reviewed-by: Kuppuswamy Sathyanarayanan <[email protected]>
---
drivers/pci/pcie/err.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
index db149c6ce4fb..05f61da5ed9d 100644
--- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
@@ -159,7 +159,7 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
*/
if (!(pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT ||
pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM))
- dev = dev->bus->self;
+ dev = pci_upstream_bridge(dev);
bus = dev->subordinate;

pci_dbg(dev, "broadcast error_detected message\n");
--
2.29.2


2020-12-03 18:50:05

by Kelley, Sean V

[permalink] [raw]
Subject: Re: [PATCH v12 05/15] PCI/ERR: Simplify by using pci_upstream_bridge()


Hi Bjorn,

Just confirming that when switched from dev->bus->self to pci_upstream_bridge() we’re okay with the NULL case:

> On Nov 20, 2020, at 4:10 PM, Sean V Kelley <[email protected]> wrote:
>
> Use pci_upstream_bridge() in place of dev->bus->self. No functional change
> intended.
>
> [bhelgaas: split to separate patch]
> Link: https://lore.kernel.org/r/[email protected]
> Signed-off-by: Sean V Kelley <[email protected]>
> Signed-off-by: Bjorn Helgaas <[email protected]>
> Acked-by: Jonathan Cameron <[email protected]>
> Reviewed-by: Kuppuswamy Sathyanarayanan <[email protected]>
> ---
> drivers/pci/pcie/err.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
> index db149c6ce4fb..05f61da5ed9d 100644
> --- a/drivers/pci/pcie/err.c
> +++ b/drivers/pci/pcie/err.c
> @@ -159,7 +159,7 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
> */
> if (!(pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT ||
> pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM))
> - dev = dev->bus->self;
> + dev = pci_upstream_bridge(dev);


The only case where pci_upstream_bridge(dev) could be NULL is if dev->bus is the root bus and we are being
selective based on the type.

Even later in this series when we actually add in RC_EC/RC_END we maintain the conditional checks:

https://lore.kernel.org/linux-pci/[email protected]/

pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,

@@ -174,10 +180,13 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,


/*
* Error recovery runs on all subordinates of the bridge. If the
- * bridge detected the error, it is cleared at the end.
+ * bridge detected the error, it is cleared at the end. For RCiEPs
+ * we should reset just the RCiEP itself.

*/
if (type == PCI_EXP_TYPE_ROOT_PORT ||
- type == PCI_EXP_TYPE_DOWNSTREAM)
+ type == PCI_EXP_TYPE_DOWNSTREAM ||
+ type == PCI_EXP_TYPE_RC_EC ||
+ type == PCI_EXP_TYPE_RC_END)
bridge = dev;
else
bridge = pci_upstream_bridge(dev);

I believe we are okay here.

Sean


> bus = dev->subordinate;
>
> pci_dbg(dev, "broadcast error_detected message\n");
> --
> 2.29.2
>
>

2020-12-03 22:30:32

by Bjorn Helgaas

[permalink] [raw]
Subject: Re: [PATCH v12 05/15] PCI/ERR: Simplify by using pci_upstream_bridge()

On Thu, Dec 03, 2020 at 06:45:00PM +0000, Kelley, Sean V wrote:
> Just confirming that when switched from dev->bus->self to
> pci_upstream_bridge() we’re okay with the NULL case:
>
> > On Nov 20, 2020, at 4:10 PM, Sean V Kelley <[email protected]> wrote:
> >
> > Use pci_upstream_bridge() in place of dev->bus->self. No functional change
> > intended.
> >
> > [bhelgaas: split to separate patch]
> > Link: https://lore.kernel.org/r/[email protected]
> > Signed-off-by: Sean V Kelley <[email protected]>
> > Signed-off-by: Bjorn Helgaas <[email protected]>
> > Acked-by: Jonathan Cameron <[email protected]>
> > Reviewed-by: Kuppuswamy Sathyanarayanan <[email protected]>
> > ---
> > drivers/pci/pcie/err.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
> > index db149c6ce4fb..05f61da5ed9d 100644
> > --- a/drivers/pci/pcie/err.c
> > +++ b/drivers/pci/pcie/err.c
> > @@ -159,7 +159,7 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
> > */
> > if (!(pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT ||
> > pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM))
> > - dev = dev->bus->self;
> > + dev = pci_upstream_bridge(dev);
>
> The only case where pci_upstream_bridge(dev) could be NULL is if
> dev->bus is the root bus and we are being selective based on the
> type.

Yes, pci_upstream_bridge(dev) returns NULL if dev is on a root bus.
I think bus->self is NULL for root buses anyway, so I think this patch
is OK at least at this point in the series.

> Even later in this series when we actually add in RC_EC/RC_END we
> maintain the conditional checks:
>
> https://lore.kernel.org/linux-pci/[email protected]/
>
> pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>
> @@ -174,10 +180,13 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>
>
> /*
> * Error recovery runs on all subordinates of the bridge. If the
> - * bridge detected the error, it is cleared at the end.
> + * bridge detected the error, it is cleared at the end. For RCiEPs
> + * we should reset just the RCiEP itself.
>
> */
> if (type == PCI_EXP_TYPE_ROOT_PORT ||
> - type == PCI_EXP_TYPE_DOWNSTREAM)
> + type == PCI_EXP_TYPE_DOWNSTREAM ||
> + type == PCI_EXP_TYPE_RC_EC ||
> + type == PCI_EXP_TYPE_RC_END)
> bridge = dev;
> else
> bridge = pci_upstream_bridge(dev);
>
> I believe we are okay here.

Well, I think we're at least no worse than today. Today we keep
"bridge == dev" for Root Ports and Downstream Ports, and use
"bridge = dev->bus->self" for everything else.

After this series we keep "bridge == dev" for RCEC and RCiEPs in
addition.

I'm not sure about PCI_EXP_TYPE_PCI_BRIDGE, which is a PCIe-to-PCI
bridge. According to the ancient "PCI Express to PCI/PCI-X Bridge
Specification" r1.0 of July 14, 2003, sec 5.23, these bridges can have
an AER Capability (with different format that I don't see mentioned
elsewhere).

But this AER Capability doesn't have the Root registers, so I assume
it would have to be below a Root Port in order to actually signal the
errors, which would mean it could not be on a root bus.

So I don't really *love* the fact that we use pci_upstream_bridge()
and rely on these assumptions that the result will not be NULL, but I
guess it's OK for now.

> > bus = dev->subordinate;
> >
> > pci_dbg(dev, "broadcast error_detected message\n");
> > --
> > 2.29.2
> >
> >
>