On Tue, Dec 08, 2015 at 10:05:56AM +0100, Sebastian Andrzej Siewior wrote:
> * Bjorn Helgaas | 2015-12-04 12:46:19 [-0600]:
>
> >The backtrace might be OK (maybe slightly overkill), but all the
> >stack addresses are certainly irrelevant and distracting. We only
> >need enough to recognize the problem. I don't think the modules list
> >is relevant either.
>
> I would shorten it to the bare minimum. Also the patch description
> itself could be truncated to the required bits…
>
> >> diff --git a/drivers/pci/host/pci-dra7xx.c b/drivers/pci/host/pci-dra7xx.c
> >> index 8c36880..0415192 100644
> >> --- a/drivers/pci/host/pci-dra7xx.c
> >> +++ b/drivers/pci/host/pci-dra7xx.c
> >> @@ -301,8 +301,19 @@ static int __init dra7xx_add_pcie_port(struct dra7xx_pcie *dra7xx,
> >> return -EINVAL;
> >> }
> >>
> >> + /*
> >> + * Mark dra7xx_pcie_msi IRQ as IRQF_NO_THREAD
> >> + * On -RT and if kernel is booting with "threadirqs" cmd line parameter
> >> + * the dra7xx_pcie_msi_irq_handler() will be forced threaded but,
> >> + * in the same time, it's IRQ dispatcher and calls generic_handle_irq(),
> >> + * which, in turn, will be resolved to handle_simple_irq() call.
> >> + * The handle_simple_irq() expected to be called with IRQ disabled, as
> >> + * result kernle will display warning:
> >> + * "irq XXX handler YYY+0x0/0x14 enabled interrupts".
> >> + */
>
> …not to mention this piece. d7ce4377494a ("powerpc/fsl_msi: mark the msi
> cascade handler IRQF_NO_THREAD") fixes the same bug in arch/ppc so they
> bypassed you fixing it.
>
> >> ret = devm_request_irq(&pdev->dev, pp->irq,
> >> - dra7xx_pcie_msi_irq_handler, IRQF_SHARED,
> >> + dra7xx_pcie_msi_irq_handler,
> >> + IRQF_SHARED | IRQF_NO_THREAD,
> >> "dra7-pcie-msi", pp);
> >
> >There's similar code in exynos_add_pcie_port(), imx6_add_pcie_port(),
> >and spear13xx_add_pcie_port(). Do they need similar changes? If not,
> >why not?
>
> You are right. The request for the handler exynos_pcie_msi_irq_handler(),
> imx6_pcie_msi_handler() and spear13xx_pcie_irq_handler() needs same
> treatment.
> Additionally we have:
>
> arch/mips/pci/msi-octeon.c: if (request_irq(OCTEON_IRQ_PCI_MSI0, octeon_msi_interrupt0,
> arch/sparc/kernel/pci_msi.c: err = request_irq(irq, sparc64_msiq_interrupt, 0,
> drivers/pci/host/pci-tegra.c: err = request_irq(msi->irq, tegra_pcie_msi_irq, 0,
> drivers/pci/host/pcie-rcar.c: err = devm_request_irq(&pdev->dev, msi->irq1, rcar_pcie_msi_irq,
> drivers/pci/host/pcie-rcar.c: err = devm_request_irq(&pdev->dev, msi->irq2, rcar_pcie_msi_irq,
> drivers/pci/host/pcie-xilinx.c: err = devm_request_irq(dev, port->irq, xilinx_pcie_intr_handler,
>
> which require the same kind of fix…
>
> >I see your discussion about DRA7 hardware design, but my impression is
> >that this problem affects anybody who calls dw_handle_msi_irq() from a
> >handler registered with IRQF_SHARED.
>
> … brecause all of them invoke generic_handle_irq() from the requsted
> handler. generic_handle_irq grabs raw_locks and this needs to run in
> raw-irq context.
> IRQF_SHARED could probably go away. The IRQ is mostlikely exclusive
> assigned in each SoC for MSI interrupt demux.
It sounds like we should fix all these places at once. If you
(Grygorii) work up a patch that does them all, with a more generic
changelog, then we can solicit testing and acks.
Bjorn
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