From: Bolarinwa Olayemi Saheed <[email protected]> On failure pcie_capability_read_dword() sets it's last parameter, val to 0. In this case dn and up will be 0, so aspm_hw_l1_supported() will return false. However, with Patch 14/14, it is possible that val is set to ~0 on failure. This would introduce a bug because (x & x) == (~0 & x). So with dn and up being 0x02, a true value is return when the read has actually failed.
This bug can be avoided if the return value of pcie_capability_read_dword is checked to confirm success. The behaviour of the function remains intact. Check the return value of pcie_capability_read_dword() to ensure success. Suggested-by: Bjorn Helgaas <[email protected]> Signed-off-by: Bolarinwa Olayemi Saheed <[email protected]> --- drivers/infiniband/hw/hfi1/aspm.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/infiniband/hw/hfi1/aspm.c b/drivers/infiniband/hw/hfi1/aspm.c index a3c53be4072c..80d0b3edd983 100644 --- a/drivers/infiniband/hw/hfi1/aspm.c +++ b/drivers/infiniband/hw/hfi1/aspm.c @@ -24,6 +24,7 @@ static bool aspm_hw_l1_supported(struct hfi1_devdata *dd) { struct pci_dev *parent = dd->pcidev->bus->self; u32 up, dn; + int ret_up, ret_dn; /* * If the driver does not have access to the upstream component, @@ -32,14 +33,14 @@ static bool aspm_hw_l1_supported(struct hfi1_devdata *dd) if (!parent) return false; - pcie_capability_read_dword(dd->pcidev, PCI_EXP_LNKCAP, &dn); + ret_dn = pcie_capability_read_dword(dd->pcidev, PCI_EXP_LNKCAP, &dn); dn = ASPM_L1_SUPPORTED(dn); - pcie_capability_read_dword(parent, PCI_EXP_LNKCAP, &up); + ret_up = pcie_capability_read_dword(parent, PCI_EXP_LNKCAP, &up); up = ASPM_L1_SUPPORTED(up); /* ASPM works on A-step but is reported as not supported */ - return (!!dn || is_ax(dd)) && !!up; + return !!ret_dn && !!ret_up && (!!dn || is_ax(dd)) && !!up; } /* Set L1 entrance latency for slower entry to L1 */ -- 2.18.2
