3.16.7-ckt24 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------ From: Grygorii Strashko <[email protected]> commit 8ff0ef996ca00028519c70e8d51d32bd37eb51dc upstream. On -RT and if kernel is booting with "threadirqs" cmd line parameter, PCIe/PCI (MSI) IRQ cascade handlers (like dra7xx_pcie_msi_irq_handler()) will be forced threaded and, as result, will generate warnings like this: WARNING: CPU: 1 PID: 82 at kernel/irq/handle.c:150 handle_irq_event_percpu+0x14c/0x174() irq 460 handler irq_default_primary_handler+0x0/0x14 enabled interrupts Backtrace: (warn_slowpath_common) from (warn_slowpath_fmt+0x38/0x40) (warn_slowpath_fmt) from (handle_irq_event_percpu+0x14c/0x174) (handle_irq_event_percpu) from (handle_irq_event+0x84/0xb8) (handle_irq_event) from (handle_simple_irq+0x90/0x118) (handle_simple_irq) from (generic_handle_irq+0x30/0x44) (generic_handle_irq) from (dra7xx_pcie_msi_irq_handler+0x7c/0x8c) (dra7xx_pcie_msi_irq_handler) from (irq_forced_thread_fn+0x28/0x5c) (irq_forced_thread_fn) from (irq_thread+0x128/0x204) This happens because all of them invoke generic_handle_irq() from the requested handler. generic_handle_irq() grabs raw_locks and thus needs to run in raw-IRQ context. This issue was originally reproduced on TI dra7-evem, but, as was identified during discussion [1], other hosts can also suffer from this issue. Fix all them at once by marking PCIe/PCI (MSI) IRQ cascade handlers IRQF_NO_THREAD explicitly. [1] http://lkml.kernel.org/r/[email protected] [bhelgaas: add stable tag, fix typos] Signed-off-by: Grygorii Strashko <[email protected]> Signed-off-by: Bjorn Helgaas <[email protected]> Acked-by: Lucas Stach <[email protected]> (for imx6) CC: Kishon Vijay Abraham I <[email protected]> CC: Jingoo Han <[email protected]> CC: Kukjin Kim <[email protected]> CC: Krzysztof Kozlowski <[email protected]> CC: Richard Zhu <[email protected]> CC: Thierry Reding <[email protected]> CC: Stephen Warren <[email protected]> CC: Alexandre Courbot <[email protected]> CC: Simon Horman <[email protected]> CC: Pratyush Anand <[email protected]> CC: Michal Simek <[email protected]> CC: "Sören Brinkmann" <[email protected]> CC: Sebastian Andrzej Siewior <[email protected]> [ luis: backported to 3.16: - dropped changes to pci-dra7xx.c, pcie-spear13xx.c, pcie-xilinx.c - adjusted context ] Signed-off-by: Luis Henriques <[email protected]> --- drivers/pci/host/pci-exynos.c | 3 ++- drivers/pci/host/pci-imx6.c | 3 ++- drivers/pci/host/pci-tegra.c | 2 +- drivers/pci/host/pcie-rcar.c | 6 ++++-- 4 files changed, 9 insertions(+), 5 deletions(-) diff --git a/drivers/pci/host/pci-exynos.c b/drivers/pci/host/pci-exynos.c index c5d0ca384502..ab8bcaabaf21 100644 --- a/drivers/pci/host/pci-exynos.c +++ b/drivers/pci/host/pci-exynos.c @@ -535,7 +535,8 @@ static int __init add_pcie_port(struct pcie_port *pp, ret = devm_request_irq(&pdev->dev, pp->msi_irq, exynos_pcie_msi_irq_handler, - IRQF_SHARED, "exynos-pcie", pp); + IRQF_SHARED | IRQF_NO_THREAD, + "exynos-pcie", pp); if (ret) { dev_err(&pdev->dev, "failed to request msi irq\n"); return ret; diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c index a568efaa331c..72cd923e4ab3 100644 --- a/drivers/pci/host/pci-imx6.c +++ b/drivers/pci/host/pci-imx6.c @@ -497,7 +497,8 @@ static int __init imx6_add_pcie_port(struct pcie_port *pp, ret = devm_request_irq(&pdev->dev, pp->msi_irq, imx6_pcie_msi_handler, - IRQF_SHARED, "mx6-pcie-msi", pp); + IRQF_SHARED | IRQF_NO_THREAD, + "mx6-pcie-msi", pp); if (ret) { dev_err(&pdev->dev, "failed to request MSI irq\n"); return -ENODEV; diff --git a/drivers/pci/host/pci-tegra.c b/drivers/pci/host/pci-tegra.c index 083cf37ca047..0407b1d6bab8 100644 --- a/drivers/pci/host/pci-tegra.c +++ b/drivers/pci/host/pci-tegra.c @@ -1280,7 +1280,7 @@ static int tegra_pcie_enable_msi(struct tegra_pcie *pcie) msi->irq = err; - err = request_irq(msi->irq, tegra_pcie_msi_irq, 0, + err = request_irq(msi->irq, tegra_pcie_msi_irq, IRQF_NO_THREAD, tegra_msi_irq_chip.name, pcie); if (err < 0) { dev_err(&pdev->dev, "failed to request IRQ: %d\n", err); diff --git a/drivers/pci/host/pcie-rcar.c b/drivers/pci/host/pcie-rcar.c index f7d3de32c9a0..b5b0d683bb2d 100644 --- a/drivers/pci/host/pcie-rcar.c +++ b/drivers/pci/host/pcie-rcar.c @@ -712,14 +712,16 @@ static int rcar_pcie_enable_msi(struct rcar_pcie *pcie) /* Two irqs are for MSI, but they are also used for non-MSI irqs */ err = devm_request_irq(&pdev->dev, msi->irq1, rcar_pcie_msi_irq, - IRQF_SHARED, rcar_msi_irq_chip.name, pcie); + IRQF_SHARED | IRQF_NO_THREAD, + rcar_msi_irq_chip.name, pcie); if (err < 0) { dev_err(&pdev->dev, "failed to request IRQ: %d\n", err); goto err; } err = devm_request_irq(&pdev->dev, msi->irq2, rcar_pcie_msi_irq, - IRQF_SHARED, rcar_msi_irq_chip.name, pcie); + IRQF_SHARED | IRQF_NO_THREAD, + rcar_msi_irq_chip.name, pcie); if (err < 0) { dev_err(&pdev->dev, "failed to request IRQ: %d\n", err); goto err;
