PCI/ASPM: Fix link_state teardown on device removal
Upon removal of the last device on a bus, the link_state of the bridge leading to that bus is sought to be torn down by having pci_stop_dev() call pcie_aspm_exit_link_state(). When ASPM was originally introduced by commit7d715a6c1a
("PCI: add PCI Express ASPM support"), it determined whether the device being removed is the last one by calling list_empty() on the bridge's subordinate devices list. That didn't work because the device is only removed from the list slightly later in pci_destroy_dev(). Commit3419c75e15
("PCI: properly clean up ASPM link state on device remove") attempted to fix it by calling list_is_last(), but that's not correct either because it checks whether the device is at the *end* of the list, not whether it's the last one *left* in the list. If the user removes the device which happens to be at the end of the list via sysfs but other devices are preceding the device in the list, the link_state is torn down prematurely. The real fix is to move the invocation of pcie_aspm_exit_link_state() to pci_destroy_dev() and reinstate the call to list_empty(). Remove a duplicate check for dev->bus->self because pcie_aspm_exit_link_state() already contains an identical check. Fixes:7d715a6c1a
("PCI: add PCI Express ASPM support") Signed-off-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: stable@vger.kernel.org # v2.6.26
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@ -991,7 +991,7 @@ void pcie_aspm_exit_link_state(struct pci_dev *pdev)
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* All PCIe functions are in one slot, remove one function will remove
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* the whole slot, so just wait until we are the last function left.
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*/
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if (!list_is_last(&pdev->bus_list, &parent->subordinate->devices))
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if (!list_empty(&parent->subordinate->devices))
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goto out;
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link = parent->link_state;
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@ -25,9 +25,6 @@ static void pci_stop_dev(struct pci_dev *dev)
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pci_dev_assign_added(dev, false);
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}
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if (dev->bus->self)
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pcie_aspm_exit_link_state(dev);
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}
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static void pci_destroy_dev(struct pci_dev *dev)
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@ -41,6 +38,7 @@ static void pci_destroy_dev(struct pci_dev *dev)
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list_del(&dev->bus_list);
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up_write(&pci_bus_sem);
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pcie_aspm_exit_link_state(dev);
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pci_bridge_d3_update(dev);
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pci_free_resources(dev);
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put_device(&dev->dev);
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