On Tue, Nov 14, 2023 at 02:55:48PM +0100, Johan Hovold wrote:
Add a helper for enabling link states that can be used in contexts where a pci_bus_sem read lock is already held (e.g. from pci_walk_bus()).
This helper will be used to fix a couple of potential deadlocks where the current helper is called with the lock already held, hence the CC stable tag.
Fixes: f492edb40b54 ("PCI: vmd: Add quirk to configure PCIe ASPM and LTR") Cc: stable@vger.kernel.org # 6.3 Cc: Michael Bottini michael.a.bottini@linux.intel.com Cc: David E. Box david.e.box@linux.intel.com Signed-off-by: Johan Hovold johan+linaro@kernel.org
With the Kdoc comment fixed,
Reviewed-by: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org
- Mani
drivers/pci/pcie/aspm.c | 53 +++++++++++++++++++++++++++++++---------- include/linux/pci.h | 3 +++ 2 files changed, 43 insertions(+), 13 deletions(-)
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index 50b04ae5c394..8cf8cc2d6bba 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -1109,17 +1109,7 @@ int pci_disable_link_state(struct pci_dev *pdev, int state) } EXPORT_SYMBOL(pci_disable_link_state); -/**
- pci_enable_link_state - Clear and set the default device link state so that
- the link may be allowed to enter the specified states. Note that if the
- BIOS didn't grant ASPM control to the OS, this does nothing because we can't
- touch the LNKCTL register. Also note that this does not enable states
- disabled by pci_disable_link_state(). Return 0 or a negative errno.
- @pdev: PCI device
- @state: Mask of ASPM link states to enable
- */
-int pci_enable_link_state(struct pci_dev *pdev, int state) +static int __pci_enable_link_state(struct pci_dev *pdev, int state, bool locked) { struct pcie_link_state *link = pcie_aspm_get_link(pdev); @@ -1136,7 +1126,8 @@ int pci_enable_link_state(struct pci_dev *pdev, int state) return -EPERM; }
- down_read(&pci_bus_sem);
- if (!locked)
down_read(&pci_bus_sem);@@ -1157,12 +1148,48 @@ int pci_enable_link_state(struct pci_dev *pdev, int state) link->clkpm_default = (state & PCIE_LINK_STATE_CLKPM) ? 1 : 0; pcie_set_clkpm(link, policy_to_clkpm_state(link)); mutex_unlock(&aspm_lock);
- up_read(&pci_bus_sem);
- if (!locked)
up_read(&pci_bus_sem);return 0; }
+/**
- pci_enable_link_state - Clear and set the default device link state so that
- the link may be allowed to enter the specified states. Note that if the
- BIOS didn't grant ASPM control to the OS, this does nothing because we can't
- touch the LNKCTL register. Also note that this does not enable states
- disabled by pci_disable_link_state(). Return 0 or a negative errno.
- @pdev: PCI device
- @state: Mask of ASPM link states to enable
- */
+int pci_enable_link_state(struct pci_dev *pdev, int state) +{
- return __pci_enable_link_state(pdev, state, false);
+} EXPORT_SYMBOL(pci_enable_link_state); +/**
- pci_enable_link_state - Clear and set the default device link state so that
- the link may be allowed to enter the specified states. Note that if the
- BIOS didn't grant ASPM control to the OS, this does nothing because we can't
- touch the LNKCTL register. Also note that this does not enable states
- disabled by pci_disable_link_state(). Return 0 or a negative errno.
- @pdev: PCI device
- @state: Mask of ASPM link states to enable
- Context: Caller holds pci_bus_sem read lock.
- */
+int pci_enable_link_state_locked(struct pci_dev *pdev, int state) +{
- lockdep_assert_held_read(&pci_bus_sem);
- return __pci_enable_link_state(pdev, state, true);
+} +EXPORT_SYMBOL(pci_enable_link_state_locked);
static int pcie_aspm_set_policy(const char *val, const struct kernel_param *kp) { diff --git a/include/linux/pci.h b/include/linux/pci.h index 60ca768bc867..dea043bc1e38 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1829,6 +1829,7 @@ extern bool pcie_ports_native; int pci_disable_link_state(struct pci_dev *pdev, int state); int pci_disable_link_state_locked(struct pci_dev *pdev, int state); int pci_enable_link_state(struct pci_dev *pdev, int state); +int pci_enable_link_state_locked(struct pci_dev *pdev, int state); void pcie_no_aspm(void); bool pcie_aspm_support_enabled(void); bool pcie_aspm_enabled(struct pci_dev *pdev); @@ -1839,6 +1840,8 @@ static inline int pci_disable_link_state_locked(struct pci_dev *pdev, int state) { return 0; } static inline int pci_enable_link_state(struct pci_dev *pdev, int state) { return 0; } +static inline int pci_enable_link_state_locked(struct pci_dev *pdev, int state) +{ return 0; } static inline void pcie_no_aspm(void) { } static inline bool pcie_aspm_support_enabled(void) { return false; } static inline bool pcie_aspm_enabled(struct pci_dev *pdev) { return false; } -- 2.41.0