[PATCH v5 1/8] PCI: Protect Link Control 2 Register with RMW locking

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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@xxxxxxxxxxxxxxx>
Reviewed-by: Lukas Wunner <lukas@xxxxxxxxx>
 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 a0027e8fb0d0..cd7857dd37aa 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 16493426a04f..93faaf08965e 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1273,6 +1273,7 @@ static inline int pcie_capability_clear_and_set_word(struct pci_dev *dev,
 	switch (pos) {
 		return pcie_capability_clear_and_set_word_locked(dev, pos,
 								 clear, set);

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