From: Bolarinwa Olayemi Saheed <[email protected]> On failure pcie_capability_read_dword() sets it's last parameter, val to 0. 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).
This bug can be avoided if the return value of pcie_capability_read_dword is checked to confirm success/failure. This check helps ensure that functions exit only when their post-condition is true. For functions which walks through device heirarchy like pci_enable_atomic_ops_to_root(), this is important. 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]> --- v4 changes: Remove unnecessary boolean conversion. Fix bugs introduced by previous changes diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 4b2a348576cb..d82b79291742 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3207,6 +3207,7 @@ void pci_configure_ari(struct pci_dev *dev) { u32 cap; struct pci_dev *bridge; + int ret; if (pcie_ari_disabled || !pci_is_pcie(dev) || dev->devfn) return; @@ -3215,8 +3216,8 @@ void pci_configure_ari(struct pci_dev *dev) if (!bridge) return; - pcie_capability_read_dword(bridge, PCI_EXP_DEVCAP2, &cap); - if (!(cap & PCI_EXP_DEVCAP2_ARI)) + ret = pcie_capability_read_dword(bridge, PCI_EXP_DEVCAP2, &cap); + if (ret || !(cap & PCI_EXP_DEVCAP2_ARI)) return; if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI)) { @@ -3606,6 +3607,7 @@ int pci_enable_atomic_ops_to_root(struct pci_dev *dev, u32 cap_mask) struct pci_bus *bus = dev->bus; struct pci_dev *bridge; u32 cap, ctl2; + int ret; if (!pci_is_pcie(dev)) return -EINVAL; @@ -3629,28 +3631,29 @@ int pci_enable_atomic_ops_to_root(struct pci_dev *dev, u32 cap_mask) while (bus->parent) { bridge = bus->self; - pcie_capability_read_dword(bridge, PCI_EXP_DEVCAP2, &cap); + ret = pcie_capability_read_dword(bridge, PCI_EXP_DEVCAP2, + &cap); switch (pci_pcie_type(bridge)) { /* Ensure switch ports support AtomicOp routing */ case PCI_EXP_TYPE_UPSTREAM: case PCI_EXP_TYPE_DOWNSTREAM: - if (!(cap & PCI_EXP_DEVCAP2_ATOMIC_ROUTE)) + if (ret || !(cap & PCI_EXP_DEVCAP2_ATOMIC_ROUTE)) return -EINVAL; break; /* Ensure root port supports all the sizes we care about */ case PCI_EXP_TYPE_ROOT_PORT: - if ((cap & cap_mask) != cap_mask) + if (ret || ((cap & cap_mask) != cap_mask)) return -EINVAL; break; } /* Ensure upstream ports don't block AtomicOps on egress */ if (pci_pcie_type(bridge) == PCI_EXP_TYPE_UPSTREAM) { - pcie_capability_read_dword(bridge, PCI_EXP_DEVCTL2, - &ctl2); - if (ctl2 & PCI_EXP_DEVCTL2_ATOMIC_EGRESS_BLOCK) + ret = pcie_capability_read_dword(bridge, + PCI_EXP_DEVCTL2, &ctl2); + if (!ret && (ctl2 & PCI_EXP_DEVCTL2_ATOMIC_EGRESS_BLOCK) return -EINVAL; } @@ -4507,12 +4510,13 @@ EXPORT_SYMBOL(pci_wait_for_pending_transaction); bool pcie_has_flr(struct pci_dev *dev) { u32 cap; + int ret; if (dev->dev_flags & PCI_DEV_FLAGS_NO_FLR_RESET) return false; - pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &cap); - return cap & PCI_EXP_DEVCAP_FLR; + ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &cap); + return (!ret && (cap & PCI_EXP_DEVCAP_FLR)); } EXPORT_SYMBOL_GPL(pcie_has_flr); @@ -4646,7 +4650,7 @@ static int pci_pm_reset(struct pci_dev *dev, int probe) static bool pcie_wait_for_link_delay(struct pci_dev *pdev, bool active, int delay) { - int timeout = 1000; + int rc, timeout = 1000; bool ret; u16 lnk_status; @@ -4671,9 +4675,9 @@ static bool pcie_wait_for_link_delay(struct pci_dev *pdev, bool active, if (active) msleep(20); for (;;) { - pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status); - ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA); - if (ret == active) + rc = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status); + ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA); + if (!rc && (ret == active)) break; if (timeout <= 0) break; @@ -4682,10 +4686,10 @@ static bool pcie_wait_for_link_delay(struct pci_dev *pdev, bool active, } if (active && ret && delay) msleep(delay); - else if (ret != active) + else if (rc || (ret != active)) pci_info(pdev, "Data Link Layer Link Active not %s in 1000 msec\n", active ? "set" : "cleared"); - return ret == active; + return (!rc && (ret == active)); } /** @@ -5774,6 +5778,7 @@ u32 pcie_bandwidth_available(struct pci_dev *dev, struct pci_dev **limiting_dev, enum pci_bus_speed next_speed; enum pcie_link_width next_width; u32 bw, next_bw; + int ret; if (speed) *speed = PCI_SPEED_UNKNOWN; @@ -5783,7 +5788,12 @@ u32 pcie_bandwidth_available(struct pci_dev *dev, struct pci_dev **limiting_dev, bw = 0; while (dev) { - pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &lnksta); + ret = pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &lnksta); + + if (ret) { + dev = pci_upstream_bridge(dev); + continue; + } next_speed = pcie_link_speed[lnksta & PCI_EXP_LNKSTA_CLS]; next_width = (lnksta & PCI_EXP_LNKSTA_NLW) >> @@ -5820,6 +5830,7 @@ EXPORT_SYMBOL(pcie_bandwidth_available); enum pci_bus_speed pcie_get_speed_cap(struct pci_dev *dev) { u32 lnkcap2, lnkcap; + int ret; /* * Link Capabilities 2 was added in PCIe r3.0, sec 7.8.18. The @@ -5830,16 +5841,18 @@ enum pci_bus_speed pcie_get_speed_cap(struct pci_dev *dev) * should use the Supported Link Speeds field in Link Capabilities, * where only 2.5 GT/s and 5.0 GT/s speeds were defined. */ - pcie_capability_read_dword(dev, PCI_EXP_LNKCAP2, &lnkcap2); + ret = pcie_capability_read_dword(dev, PCI_EXP_LNKCAP2, &lnkcap2); /* PCIe r3.0-compliant */ - if (lnkcap2) + if (!ret && lnkcap2) return PCIE_LNKCAP2_SLS2SPEED(lnkcap2); - pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &lnkcap); - if ((lnkcap & PCI_EXP_LNKCAP_SLS) == PCI_EXP_LNKCAP_SLS_5_0GB) + ret = pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &lnkcap); + if (!ret && + ((lnkcap & PCI_EXP_LNKCAP_SLS) == PCI_EXP_LNKCAP_SLS_5_0GB)) return PCIE_SPEED_5_0GT; - else if ((lnkcap & PCI_EXP_LNKCAP_SLS) == PCI_EXP_LNKCAP_SLS_2_5GB) + else if (!ret && + ((lnkcap & PCI_EXP_LNKCAP_SLS) == PCI_EXP_LNKCAP_SLS_2_5GB)) return PCIE_SPEED_2_5GT; return PCI_SPEED_UNKNOWN; @@ -5856,9 +5869,10 @@ EXPORT_SYMBOL(pcie_get_speed_cap); enum pcie_link_width pcie_get_width_cap(struct pci_dev *dev) { u32 lnkcap; + int ret; - pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &lnkcap); - if (lnkcap) + ret = pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &lnkcap); + if (!ret && lnkcap) return (lnkcap & PCI_EXP_LNKCAP_MLW) >> 4; return PCIE_LNK_WIDTH_UNKNOWN;
