[PATCH v7 1/8] PCI: Protect Link Control 2 Register with RMW locking

Ilpo Järvinen
2024-09-10T12:27:34Z

PCIe Bandwidth Controller performs RMW accesses the Link Control 2
Register which can occur concurrently to other sources of Link Control
2 Register writes. Therefore, add Link Control 2 Register among the PCI
Express Capability Registers that need RMW locking.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
---
Documentation/PCI/pciebus-howto.rst | 14 +++++++++-----
include/linux/pci.h | 1 +
2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/Documentation/PCI/pciebus-howto.rst b/Documentation/PCI/pciebus-howto.rst
index f344452651e1..375d9ce171f6 100644
--- a/Documentation/PCI/pciebus-howto.rst
+++ b/Documentation/PCI/pciebus-howto.rst
@@ -217,8 +217,12 @@ capability structure except the PCI Express capability structure,
that is shared between many drivers including the service drivers.
RMW Capability accessors (pcie_capability_clear_and_set_word(),
pcie_capability_set_word(), and pcie_capability_clear_word()) protect
-a selected set of PCI Express Capability Registers (Link Control
-Register and Root Control Register). Any change to those registers
-should be performed using RMW accessors to avoid problems due to
-concurrent updates. For the up-to-date list of protected registers,
-see pcie_capability_clear_and_set_word().
+a selected set of PCI Express Capability Registers:
+
+* Link Control Register
+* Root Control Register
+* Link Control 2 Register
+
+Any change to those registers should be performed using RMW accessors to
+avoid problems due to concurrent updates. For the up-to-date list of
+protected registers, see pcie_capability_clear_and_set_word().
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 4cf89a4b4cbc..25362d577824 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1270,6 +1270,7 @@ static inline int pcie_capability_clear_and_set_word(struct pci_dev *dev,
{
switch (pos) {
case PCI_EXP_LNKCTL:
+ case PCI_EXP_LNKCTL2:
case PCI_EXP_RTCTL:
return pcie_capability_clear_and_set_word_locked(dev, pos,
clear, set);
--
2.39.2