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c8fc933940
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> |
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| .. | ||
| aer | ||
| aspm.c | ||
| Kconfig | ||
| Makefile | ||
| pme.c | ||
| portdrv.h | ||
| portdrv_acpi.c | ||
| portdrv_bus.c | ||
| portdrv_core.c | ||
| portdrv_pci.c | ||