[PATCH v4 08/12] PCI: Check if pcie_capability_read_*() reads ~0

[Saheed O. Bolarinwa]

On failure pcie_capability_read_*() sets it's last parameter, val
to 0. However, with Patch 12/12, it is possible that val is set
to ~0 on failure. This would introduce a bug because
(x & x) == (~0 & x).

Since ~0 is an invalid value in here,

Add extra check for ~0 in the if condition to ensure success or
failure.

Suggested-by: Bjorn Helgaas <bj...@helgaas.com>
Signed-off-by: Saheed O. Bolarinwa <refactormys...@gmail.com>
---
 drivers/pci/probe.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 2f66988cea25..af95f67c19a7 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1124,7 +1124,7 @@ static void pci_enable_crs(struct pci_dev *pdev)
 
        /* Enable CRS Software Visibility if supported */
        pcie_capability_read_word(pdev, PCI_EXP_RTCAP, &root_cap);
-       if (root_cap & PCI_EXP_RTCAP_CRSVIS)
+       if ((root_cap != (u16)~0) && (root_cap & PCI_EXP_RTCAP_CRSVIS))
                pcie_capability_set_word(pdev, PCI_EXP_RTCTL,
                                         PCI_EXP_RTCTL_CRSSVE);
 }
@@ -1521,7 +1521,7 @@ void set_pcie_hotplug_bridge(struct pci_dev *pdev)
        u32 reg32;
 
        pcie_capability_read_dword(pdev, PCI_EXP_SLTCAP, &reg32);
-       if (reg32 & PCI_EXP_SLTCAP_HPC)
+       if ((reg32 != (u32)~0) && (reg32 & PCI_EXP_SLTCAP_HPC))
                pdev->is_hotplug_bridge = 1;
 }
 
@@ -2060,7 +2060,7 @@ bool pcie_relaxed_ordering_enabled(struct pci_dev *dev)
 
        pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &v);
 
-       return !!(v & PCI_EXP_DEVCTL_RELAX_EN);
+       return ((v != (u16)~0) && (v & PCI_EXP_DEVCTL_RELAX_EN));
 }
 EXPORT_SYMBOL(pcie_relaxed_ordering_enabled);
 
@@ -2101,11 +2101,11 @@ static void pci_configure_ltr(struct pci_dev *dev)
                return;
 
        pcie_capability_read_dword(dev, PCI_EXP_DEVCAP2, &cap);
-       if (!(cap & PCI_EXP_DEVCAP2_LTR))
+       if ((cap == (u32)~0) || !(cap & PCI_EXP_DEVCAP2_LTR))
                return;
 
        pcie_capability_read_dword(dev, PCI_EXP_DEVCTL2, &ctl);
-       if (ctl & PCI_EXP_DEVCTL2_LTR_EN) {
+       if ((ctl != (u32)~0) && (ctl & PCI_EXP_DEVCTL2_LTR_EN)) {
                if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) {
                        dev->ltr_path = 1;
                        return;
@@ -2147,7 +2147,7 @@ static void pci_configure_eetlp_prefix(struct pci_dev 
*dev)
                return;
 
        pcie_capability_read_dword(dev, PCI_EXP_DEVCAP2, &cap);
-       if (!(cap & PCI_EXP_DEVCAP2_EE_PREFIX))
+       if ((cap == (u32)~0) || !(cap & PCI_EXP_DEVCAP2_EE_PREFIX))
                return;
 
        pcie_type = pci_pcie_type(dev);
-- 
2.18.4