| Message ID | 4516b02d3c0fe3593a1a9f59bab47e99cdb65f02.1634306198.git.naveennaidu479@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Unify PCI error response checking | expand |
On Fri, Oct 15, 2021 at 07:58:16PM +0530, Naveen Naidu wrote: > An MMIO read from a PCI device that doesn't exist or doesn't respond > causes a PCI error. There's no real data to return to satisfy the > CPU read, so most hardware fabricates ~0 data. > > Add a PCI_ERROR_RESPONSE definition for that and use it where > appropriate to make these checks consistent and easier to find. > > Also add helper definitions SET_PCI_ERROR_RESPONSE and > RESPONSE_IS_PCI_ERROR to make the code more readable. > > Suggested-by: Bjorn Helgaas <bhelgaas@google.com> > Signed-off-by: Naveen Naidu <naveennaidu479@gmail.com> > --- > include/linux/pci.h | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/include/linux/pci.h b/include/linux/pci.h > index cd8aa6fce204..928c589bb5c4 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -154,6 +154,15 @@ enum pci_interrupt_pin { > /* The number of legacy PCI INTx interrupts */ > #define PCI_NUM_INTX 4 > > +/* > + * Reading from a device that doesn't respond typically returns ~0. A > + * successful read from a device may also return ~0, so you need additional > + * information to reliably identify errors. > + */ > +#define PCI_ERROR_RESPONSE (~0ULL) > +#define SET_PCI_ERROR_RESPONSE(val) (*val = ((typeof(*val)) PCI_ERROR_RESPONSE)) > +#define RESPONSE_IS_PCI_ERROR(val) (*val == ((typeof(*val)) PCI_ERROR_RESPONSE)) No reason for val to be a pointer. Also, macro parameters need () around them. val could be an expression like 'ptr + 1' which would blow up for example. > + > /* > * pci_power_t values must match the bits in the Capabilities PME_Support > * and Control/Status PowerState fields in the Power Management capability. > -- > 2.25.1 > >
diff --git a/include/linux/pci.h b/include/linux/pci.h index cd8aa6fce204..928c589bb5c4 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -154,6 +154,15 @@ enum pci_interrupt_pin { /* The number of legacy PCI INTx interrupts */ #define PCI_NUM_INTX 4 +/* + * Reading from a device that doesn't respond typically returns ~0. A + * successful read from a device may also return ~0, so you need additional + * information to reliably identify errors. + */ +#define PCI_ERROR_RESPONSE (~0ULL) +#define SET_PCI_ERROR_RESPONSE(val) (*val = ((typeof(*val)) PCI_ERROR_RESPONSE)) +#define RESPONSE_IS_PCI_ERROR(val) (*val == ((typeof(*val)) PCI_ERROR_RESPONSE)) + /* * pci_power_t values must match the bits in the Capabilities PME_Support * and Control/Status PowerState fields in the Power Management capability.
An MMIO read from a PCI device that doesn't exist or doesn't respond causes a PCI error. There's no real data to return to satisfy the CPU read, so most hardware fabricates ~0 data. Add a PCI_ERROR_RESPONSE definition for that and use it where appropriate to make these checks consistent and easier to find. Also add helper definitions SET_PCI_ERROR_RESPONSE and RESPONSE_IS_PCI_ERROR to make the code more readable. Suggested-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Naveen Naidu <naveennaidu479@gmail.com> --- include/linux/pci.h | 9 +++++++++ 1 file changed, 9 insertions(+)