PCI/ERR: Use PCI_POSSIBLE_ERROR() to check config reads

When config pci_ops.read() can detect failed PCI transactions, the data
returned to the CPU is PCI_ERROR_RESPONSE (~0 or 0xffffffff).

Obviously a successful PCI config read may *also* return that data if a
config register happens to contain ~0, so it doesn't definitively indicate
an error unless we know the register cannot contain ~0.

Use PCI_POSSIBLE_ERROR() to check the response we get when we read data
from hardware.  This unifies PCI error response checking and makes error
checks consistent and easier to find.

Link: https://lore.kernel.org/r/f4d18d470cb90f9cb52ea155b01528ba2e76e8d6.1637243717.git.naveennaidu479@gmail.com
Signed-off-by: Naveen Naidu <naveennaidu479@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 3d2fb394986a4eba685fce6ae2726798f5acea19..bc82699ed105d0546793da1aa2a49c37f86068ed 100644 (file)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1115,7 +1115,7 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state)
                return -EIO;
 
        pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
-       if (pmcsr == (u16) ~0) {
+       if (PCI_POSSIBLE_ERROR(pmcsr)) {
                pci_err(dev, "can't change power state from %s to %s (config space inaccessible)\n",
                        pci_power_name(dev->current_state),
                        pci_power_name(state));
@@ -1271,16 +1271,16 @@ static int pci_dev_wait(struct pci_dev *dev, char *reset_type, int timeout)
         * After reset, the device should not silently discard config
         * requests, but it may still indicate that it needs more time by
         * responding to them with CRS completions.  The Root Port will
-        * generally synthesize ~0 data to complete the read (except when
-        * CRS SV is enabled and the read was for the Vendor ID; in that
-        * case it synthesizes 0x0001 data).
+        * generally synthesize ~0 (PCI_ERROR_RESPONSE) data to complete
+        * the read (except when CRS SV is enabled and the read was for the
+        * Vendor ID; in that case it synthesizes 0x0001 data).
         *
         * Wait for the device to return a non-CRS completion.  Read the
         * Command register instead of Vendor ID so we don't have to
         * contend with the CRS SV value.
         */
        pci_read_config_dword(dev, PCI_COMMAND, &id);
-       while (id == ~0) {
+       while (PCI_POSSIBLE_ERROR(id)) {
                if (delay > timeout) {
                        pci_warn(dev, "not ready %dms after %s; giving up\n",
                                 delay - 1, reset_type);

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 087d3658f75cef27021d10fc402896ff14b46a57..c48fe1ab196117af23fdc3fdbb4118701a6bf27f 100644 (file)
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -206,14 +206,14 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
         * memory BAR or a ROM, bit 0 must be clear; if it's an io BAR, bit
         * 1 must be clear.
         */
-       if (sz == 0xffffffff)
+       if (PCI_POSSIBLE_ERROR(sz))
                sz = 0;
 
        /*
         * I don't know how l can have all bits set.  Copied from old code.
         * Maybe it fixes a bug on some ancient platform.
         */
-       if (l == 0xffffffff)
+       if (PCI_POSSIBLE_ERROR(l))
                l = 0;
 
        if (type == pci_bar_unknown) {
@@ -1683,7 +1683,7 @@ static int pci_cfg_space_size_ext(struct pci_dev *dev)
 
        if (pci_read_config_dword(dev, pos, &status) != PCIBIOS_SUCCESSFUL)
                return PCI_CFG_SPACE_SIZE;
-       if (status == 0xffffffff || pci_ext_cfg_is_aliased(dev))
+       if (PCI_POSSIBLE_ERROR(status) || pci_ext_cfg_is_aliased(dev))
                return PCI_CFG_SPACE_SIZE;
 
        return PCI_CFG_SPACE_EXP_SIZE;
@@ -2371,8 +2371,8 @@ bool pci_bus_generic_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
        if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, l))
                return false;
 
-       /* Some broken boards return 0 or ~0 if a slot is empty: */
-       if (*l == 0xffffffff || *l == 0x00000000 ||
+       /* Some broken boards return 0 or ~0 (PCI_ERROR_RESPONSE) if a slot is empty: */
+       if (PCI_POSSIBLE_ERROR(*l) || *l == 0x00000000 ||
            *l == 0x0000ffff || *l == 0xffff0000)
                return false;