On Thu, 31 Jan 2013, Myron Stowe wrote: > On Fri, 2013-01-18 at 13:23 -0500, Joe Lawrence wrote: > > From 3a51bbad5555ba6c6e144aa5176c8112eb449325 Mon Sep 17 00:00:00 2001 > > From: Joe Lawrence <joe.lawrence@xxxxxxxxxxx> > > Date: Tue, 15 Jan 2013 14:51:57 -0500 > > Subject: [PATCH 1/2] PCI: ASPM exit link state code could skip devices > > > > On PCI bus hotplug removal, pcie_aspm_exit_link_state could potentially skip > > parent devices that have link_state allocated. Instead of exiting early if > > a given device is not PCIe, check that the device's parent is PCIe. This > > enables pcie_aspm_exit_link_state to properly clean up parent link_state when > > the last function in a slot might not be PCIe. > > > > Reviewed-by: David Bulkow <david.bulkow@xxxxxxxxxxx> > > Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxxx> > > --- > > drivers/pci/pcie/aspm.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c > > index b52630b..6122447 100644 > > --- a/drivers/pci/pcie/aspm.c > > +++ b/drivers/pci/pcie/aspm.c > > @@ -634,7 +634,7 @@ void pcie_aspm_exit_link_state(struct pci_dev *pdev) > > struct pci_dev *parent = pdev->bus->self; > > struct pcie_link_state *link, *root, *parent_link; > > > > - if (!pci_is_pcie(pdev) || !parent || !parent->link_state) > > + if (!parent || !pci_is_pcie(parent) || !parent->link_state) > > return; > > if ((pci_pcie_type(parent) != PCI_EXP_TYPE_ROOT_PORT) && > > (pci_pcie_type(parent) != PCI_EXP_TYPE_DOWNSTREAM)) > > Joe: > > Bjorn and I looked at this again today and think the checks that occur > early in 'pcie_aspm_exit_link_state()' could be simplified (as shown > below) to avoid issues such as you are encountering. > > I think part of the confusion concerning the asymmetry between > 'pcie_aspm_init_link_state()' and 'pcie_aspm_exit_link_state()' is that > the former is passed in a pointer to a bridge device whereas the latter > is passed in a pointer to a end-point device. Frankly, I find the > entire driver to be confusing and very hard to understand. > > Could you please test with the following patch and let us know the > results? > > > PCI: ASPM exit link state code is skipping devices > > From: Myron Stowe <myron.stowe@xxxxxxxxxx> > > On PCI bus hotplug removal, 'pcie_aspm_exit_link_state' can potentially > skip parent devices that have link_state allocated. Instead of exiting > early if a given device in not PCIe, check whether or not the device's > parent has link_state allocated. This enables 'pcie_aspm_exit_link_state' > to properly clean up parent link_state when the last function in a slot > might not be PCIe. > > Reported-by: Joe Lawrence <joe.lawrence@xxxxxxxxxxx> > Signed-off-by: Myron Stowe <myron.stowe@xxxxxxxxxx> > --- > > drivers/pci/pcie/aspm.c | 5 +---- > 1 files changed, 1 insertions(+), 4 deletions(-) > > > diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c > index 8474b6a..aa52727 100644 > --- a/drivers/pci/pcie/aspm.c > +++ b/drivers/pci/pcie/aspm.c > @@ -634,10 +634,7 @@ void pcie_aspm_exit_link_state(struct pci_dev *pdev) > struct pci_dev *parent = pdev->bus->self; > struct pcie_link_state *link, *root, *parent_link; > > - if (!pci_is_pcie(pdev) || !parent || !parent->link_state) > - return; > - if ((pci_pcie_type(parent) != PCI_EXP_TYPE_ROOT_PORT) && > - (pci_pcie_type(parent) != PCI_EXP_TYPE_DOWNSTREAM)) > + if (!parent || !parent->link_state) > return; > > down_read(&pci_bus_sem); > > > Hi Myron, The patch tests eliminates the reported crash when hotplugging our problem PCI bus. The additional checks removed from pcie_aspm_exit_link_state (ie, the simplification) do appear to be unnecessary as pcie_aspm_init_link_state is already preventing such devices from allocating link state. Thanks, -- Joe -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
