diff options
| author | Yijing Wang <wangyijing@huawei.com> | 2015-05-21 10:05:03 +0300 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2015-05-26 20:56:47 +0300 |
| commit | c8fc9339409df88693742d323819ab8415cd2e9d (patch) | |
| tree | 56e8d688204f8f8ffc36eb1962b8c156bced6440 /drivers/pci/pcie | |
| parent | d0751b98dfa391f862e02dc36a233a54615e3f1d (diff) | |
| download | linux-c8fc9339409df88693742d323819ab8415cd2e9d.tar.xz | |
PCI/ASPM: Use dev->has_secondary_link to find downstream links
We allocate pcie_link_state for the component at the upstream end of a
Link. Previously we did this by allocating pcie_link_state for Root Ports
and Downstream Ports. This works fine for the typical topology:
00:1c.0 Root Port [bridge to bus 02]
02:00.0 Upstream Port [bridge to bus 03]
03:00.0 Downstream Port [bridge to bus 04]
04:00.0 Endpoint or Switch Port
However, it is possible to have a Root Port connected to a Downstream Port
instead of an Upstream Port, as in Robert White's ATCA system:
00:1c.0 Root Port [bridge to bus 02]
02:00.0 Downstream Port [bridge to bus 03]
03:01.0 Downstream Port [bridge to bus 04]
04:00.0 Endpoint or Switch Port
In this topology, we wrongly allocated pcie_link_state for the 02:00.0
Downstream Port, which is actually the *downstream* end of a link. This
led to the following NULL pointer dereference when we tried to connect this
link into the tree of links starting at the 00:1c.0 Root Port:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000088
IP: [<ffffffff81550324>] pcie_aspm_init_link_state+0x744/0x850
Hardware name: Kontron B3001/B3001, BIOS 4.6.3 08/07/2012
Call Trace:
[<ffffffff8153b865>] pci_scan_slot+0xd5/0x120
[<ffffffff8153ca1d>] pci_scan_child_bus+0x2d/0xd0
...
Instead of relying on the component type to identify the upstream end of a
link, use the "dev->has_secondary_link" field.
This means it's now possible for an Upstream Port to have a link on its
secondary side, so alloc_pcie_link_state() needs to connect links
originating from both Upstream and Downstream Ports into the tree.
[bhelgaas: changelog, add comment]
Link: https://bugzilla.kernel.org/show_bug.cgi?id=94361
Link: http://lkml.kernel.org/r/54EB81B2.4050904@pobox.com
Reported-by: Robert White <rwhite@pobox.com>
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Diffstat (limited to 'drivers/pci/pcie')
| -rw-r--r-- | drivers/pci/pcie/aspm.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index 4e1af7637501..a84f87247d2f 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -525,7 +525,7 @@ static struct pcie_link_state *alloc_pcie_link_state(struct pci_dev *pdev) INIT_LIST_HEAD(&link->children); INIT_LIST_HEAD(&link->link); link->pdev = pdev; - if (pci_pcie_type(pdev) == PCI_EXP_TYPE_DOWNSTREAM) { + if (pci_pcie_type(pdev) != PCI_EXP_TYPE_ROOT_PORT) { struct pcie_link_state *parent; parent = pdev->bus->parent->self->link_state; if (!parent) { @@ -559,10 +559,15 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev) if (!aspm_support_enabled) return; - if (!pci_is_pcie(pdev) || pdev->link_state) + if (pdev->link_state) return; - if (pci_pcie_type(pdev) != PCI_EXP_TYPE_ROOT_PORT && - pci_pcie_type(pdev) != PCI_EXP_TYPE_DOWNSTREAM) + + /* + * We allocate pcie_link_state for the component on the upstream + * end of a Link, so there's nothing to do unless this device has a + * Link on its secondary side. + */ + if (!pdev->has_secondary_link) return; /* VIA has a strange chipset, root port is under a bridge */ @@ -715,8 +720,7 @@ static void __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem) if (!pci_is_pcie(pdev)) return; - if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT || - pci_pcie_type(pdev) == PCI_EXP_TYPE_DOWNSTREAM) + if (pdev->has_secondary_link) parent = pdev; if (!parent || !parent->link_state) return; |