[Linux-kernel-mentees] [PATCH v4 11/12] PCI/ASPM: Check if pcie_capability_read_*() reads ~0
From: Saheed O. Bolarinwa <hidden>
Date: 2020-07-31 12:43:20
Also in:
linux-pci, lkml
Subsystem:
pci subsystem, the rest · Maintainers:
Bjorn Helgaas, Linus Torvalds
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 to the if condition to confirm failure. Suggested-by: Bjorn Helgaas <redacted> Signed-off-by: Saheed O. Bolarinwa <redacted> --- drivers/pci/pcie/aspm.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index b17e5ffd31b1..5e84a5ee94b0 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c@@ -223,7 +223,7 @@ static bool pcie_retrain_link(struct pcie_link_state *link) end_jiffies = jiffies + LINK_RETRAIN_TIMEOUT; do { pcie_capability_read_word(parent, PCI_EXP_LNKSTA, ®16); - if (!(reg16 & PCI_EXP_LNKSTA_LT)) + if ((reg16 == (u16)~0) || !(reg16 & PCI_EXP_LNKSTA_LT)) break; msleep(1); } while (time_before(jiffies, end_jiffies));
@@ -250,23 +250,23 @@ static void pcie_aspm_configure_common_clock(struct pcie_link_state *link) /* Check downstream component if bit Slot Clock Configuration is 1 */ pcie_capability_read_word(child, PCI_EXP_LNKSTA, ®16); - if (!(reg16 & PCI_EXP_LNKSTA_SLC)) + if ((reg16 == (u16)~0) || !(reg16 & PCI_EXP_LNKSTA_SLC)) same_clock = 0; /* Check upstream component if bit Slot Clock Configuration is 1 */ pcie_capability_read_word(parent, PCI_EXP_LNKSTA, ®16); - if (!(reg16 & PCI_EXP_LNKSTA_SLC)) + if ((reg16 == (u16)~0) || !(reg16 & PCI_EXP_LNKSTA_SLC)) same_clock = 0; /* Port might be already in common clock mode */ pcie_capability_read_word(parent, PCI_EXP_LNKCTL, ®16); - if (same_clock && (reg16 & PCI_EXP_LNKCTL_CCC)) { + if ((reg16 != (u16)~0) && same_clock && (reg16 & PCI_EXP_LNKCTL_CCC)) { bool consistent = true; list_for_each_entry(child, &linkbus->devices, bus_list) { pcie_capability_read_word(child, PCI_EXP_LNKCTL, ®16); - if (!(reg16 & PCI_EXP_LNKCTL_CCC)) { + if ((reg16 == (u16)~0) || !(reg16 & PCI_EXP_LNKCTL_CCC)) { consistent = false; break; }
--
2.18.4
_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees