On Wed, Mar 01, 2017 at 12:25:40AM -0800, Yinghai Lu wrote:
> ~ # echo 1 > /sys/bus/pci/devices/0000\:0b\:00.0/remove
> ...
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
> IP: pcie_config_aspm_link+0x5d/0x2b0
> Call Trace:
> pcie_aspm_exit_link_state+0x75/0x130
> pci_stop_bus_device+0xa4/0xb0
> pci_stop_and_remove_bus_device_locked+0x1a/0x30
> remove_store+0x50/0x70
> dev_attr_store+0x18/0x30
> sysfs_kf_write+0x44/0x60
> kernfs_fop_write+0x10e/0x190
> __vfs_write+0x28/0x110
> ? rcu_read_lock_sched_held+0x5d/0x80
> ? rcu_sync_lockdep_assert+0x2c/0x60
> ? __sb_start_write+0x173/0x1a0
> ? vfs_write+0xb3/0x180
> vfs_write+0xc4/0x180
> SyS_write+0x49/0xa0
> do_syscall_64+0xa6/0x1c0
> entry_SYSCALL64_slow_path+0x25/0x25
> ---[ end trace bd187ee0267df5d9 ]---
>
> set downstream even with blacklist path.
>
> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
Applied with Rajat's ack to for-linus for v4.11, thanks!
I added a stable tag, since I think this bug has been there a long time and
it causes a NULL pointer dereference.
> ---
> drivers/pci/pcie/aspm.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> Index: linux-2.6/drivers/pci/pcie/aspm.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/pcie/aspm.c
> +++ linux-2.6/drivers/pci/pcie/aspm.c
> @@ -478,7 +478,7 @@ static void aspm_calc_l1ss_info(struct p
>
> static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
> {
> - struct pci_dev *child, *parent = link->pdev;
> + struct pci_dev *child = link->downstream, *parent = link->pdev;
> struct pci_bus *linkbus = parent->subordinate;
> struct aspm_register_info upreg, dwreg;
>
> @@ -491,9 +491,7 @@ static void pcie_aspm_cap_init(struct pc
>
> /* Get upstream/downstream components' register state */
> pcie_get_aspm_reg(parent, &upreg);
> - child = pci_function_0(linkbus);
> pcie_get_aspm_reg(child, &dwreg);
> - link->downstream = child;
>
> /*
> * If ASPM not supported, don't mess with the clocks and link,
> @@ -800,6 +798,7 @@ static struct pcie_link_state *alloc_pci
> INIT_LIST_HEAD(&link->children);
> INIT_LIST_HEAD(&link->link);
> link->pdev = pdev;
> + link->downstream = pci_function_0(pdev->subordinate);
>
> /*
> * Root Ports and PCI/PCI-X to PCIe Bridges are roots of PCIe
