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    SubjectRe: [PATCH 0/2] PCI: PCI-E MPS bug fixes
    From
    On Tue, Sep 13, 2011 at 1:17 PM, Benjamin Herrenschmidt
    <benh@kernel.crashing.org> wrote:
    > On Tue, 2011-09-13 at 07:50 -0300, Benjamin Herrenschmidt wrote:
    >> >
    >> > You should apply them. I would queue them, and but I don't have
    >> > another PCI tree anywhere for you to pull them.
    >> >
    >> > In fact, I'll be out for the next few weeks; I'll ask Bjorn to cover
    >> > for me.
    >>
    >> Note that I might be missing some patches, but what's currently in Linus
    >> tree is rather wrong.
    >>
    >> The comment is right, but the implementation is bogus:
    >
    > Oh and another one (again, I never saw the patches I'm responding to for
    > some odd reason, only email 0/2, so you might have already fixed that):

    DNS issue with kernel.org when the patches went out caused it to not
    get out to any of the mailing lists.

    In Linux' github tree
    Patch 1/2 is commit 5307f6d5fb12fd01f9f321bc4a8fd77e74858647
    Patch 2/2 is commit ed2888e906b56769b4ffabb9c577190438aa68b8

    > When using "safe" mode, I get a crash in pcie_find_smpss(). Patch below.
    >
    > From 1b542d690323fab332e61099193d598c5c515d13 Mon Sep 17 00:00:00 2001
    > From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    > Date: Tue, 13 Sep 2011 15:16:33 -0300
    > Subject: [PATCH] pci: Don't crash when reading mpss from root complex
    >
    > In pcie_find_smpss(), we have the following statement:
    >
    >        if (dev->is_hotplug_bridge && (!list_is_singular(&dev->bus->devices) ||
    >            dev->bus->self->pcie_type != PCI_EXP_TYPE_ROOT_PORT))
    >
    > The problem is that at least on my machine, this gets called for the
    > root complex (virtual P2P bridge), and dev->bus->self is NULL since
    > the parent bus for this is not itself anchor to a PCI device.
    >
    > This adds the necessary NULL check.
    >
    > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

    Good catch.

    Acked-by: Jon Mason <mason@myri.com>

    > ---
    >  drivers/pci/probe.c |    3 ++-
    >  1 files changed, 2 insertions(+), 1 deletions(-)
    >
    > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
    > index 8473727..09d1c0f 100644
    > --- a/drivers/pci/probe.c
    > +++ b/drivers/pci/probe.c
    > @@ -1351,7 +1351,8 @@ static int pcie_find_smpss(struct pci_dev *dev, void *data)
    >         * will occur as normal.
    >         */
    >        if (dev->is_hotplug_bridge && (!list_is_singular(&dev->bus->devices) ||
    > -           dev->bus->self->pcie_type != PCI_EXP_TYPE_ROOT_PORT))
    > +            (dev->bus->self &&
    > +             dev->bus->self->pcie_type != PCI_EXP_TYPE_ROOT_PORT)))
    >                *smpss = 0;
    >
    >        if (*smpss > dev->pcie_mpss)
    > --
    > 1.7.4.1
    >
    >
    >
    >
    >
    >
    >
    --
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