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    SubjectRe: linux-next: OOPS at bot time
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    On Fri, 2010-07-23 at 02:19 +0100, Ben Hutchings wrote:
    > On Fri, 2010-07-23 at 10:22 +1000, Stephen Rothwell wrote:
    > > Hi all,
    > >
    > > My Power7 boot test paniced like this: (next-20100722)
    > >
    > > %GQLogic Fibre Channel HBA Driver: 8.03.03-k0
    > > qla2xxx 0002:01:00.2: enabling device (0144 -> 0146)
    > > qla2xxx 0002:01:00.2: Found an ISP8001, irq 35, iobase 0xd000080080014000
    > > ------------[ cut here ]------------
    > > kernel BUG at drivers/pci/msi.c:205!
    > [...]
    > > Call Trace:
    > > [c00000000278b270] [c000000000048d9c] .rtas_setup_msi_irqs+0x1d8/0x254 (unreliable)
    > > [c00000000278b360] [c00000000002a9cc] .arch_setup_msi_irqs+0x34/0x4c
    > > [c00000000278b3e0] [c0000000002fd3fc] .pci_enable_msix+0x49c/0x4ac
    > [...]
    > > That line number is this:
    > >
    > > BUG_ON(!(entry->msg.address_hi | entry->msg.address_lo |
    > > entry->msg.data));
    > >
    > > in read_msi_msg_desc(). That BUG_ON was added by commit
    > > 2ca1af9aa3285c6a5f103ed31ad09f7399fc65d7 ("PCI: MSI: Remove unsafe and
    > > unnecessary hardware access") from the pci tree.
    >
    > I wanted to assert that read_msi_msg_desc() is only used to update
    > MSI/MSI-X descriptors that have already been generated by Linux. It
    > looks like you found an exception.
    >
    > We could make read_msi_msg() fall back to reading from the hardware, but
    > I think that what the pSeries code is trying to do - save an MSI message
    > generated by firmware - is different from what the other callers want.
    > Instead we could add:
    >
    > void save_msi_msg(unsigned int irq)
    > {
    > struct irq_desc *desc = irq_to_desc(irq);
    > struct msi_desc *entry = get_irq_desc_msi(desc);
    > struct msi_msg *msg = &entry->msg;
    >
    > /* ...followed by the old implementation of read_msi_msg_desc() */
    > }
    >
    > Possibly conditional on something like CONFIG_ARCH_NEEDS_SAVE_MSI_MSG.

    Maybe.

    But then you end up with read_msi_msg(), which doesn't actually read
    anything, which I think is confusing. I'd rather read_msi_msg() read the
    message, from the device, and we have another routine which returns the
    previously saved msg from the msi_desc.

    cheers
    [unhandled content-type:application/pgp-signature]
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