From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Andrzej Siewior Subject: Re: [PATCH v2] PCI: dra7xx: mark dra7xx_pcie_msi irq as IRQF_NO_THREAD Date: Tue, 8 Dec 2015 10:05:56 +0100 Message-ID: <20151208090555.GA19438@linutronix.de> References: <1448027966-21610-1-git-send-email-grygorii.strashko@ti.com> <20151204184619.GD20125@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <20151204184619.GD20125@localhost> Sender: linux-pci-owner@vger.kernel.org To: Bjorn Helgaas Cc: Grygorii Strashko , Kishon Vijay Abraham I , Bjorn Helgaas , tony@atomide.com, nsekhar@ti.com, linux-omap@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Thomas Gleixner List-Id: linux-omap@vger.kernel.org * 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=E2=80=A6 >> diff --git a/drivers/pci/host/pci-dra7xx.c b/drivers/pci/host/pci-dr= a7xx.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 d= ra7xx_pcie *dra7xx, >> return -EINVAL; >> } >> =20 >> + /* >> + * Mark dra7xx_pcie_msi IRQ as IRQF_NO_THREAD >> + * On -RT and if kernel is booting with "threadirqs" cmd line para= meter >> + * 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". >> + */ =E2=80=A6not to mention this piece. d7ce4377494a ("powerpc/fsl_msi: mar= k the msi cascade handler IRQF_NO_THREAD") fixes the same bug in arch/ppc so they bypassed you fixing it. >> ret =3D 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 =3D request_irq(irq, sparc64_msiq_i= nterrupt, 0, drivers/pci/host/pci-tegra.c: err =3D request_irq(msi->irq, tegra_pci= e_msi_irq, 0, drivers/pci/host/pcie-rcar.c: err =3D devm_request_irq(&pdev->dev, ms= i->irq1, rcar_pcie_msi_irq, drivers/pci/host/pcie-rcar.c: err =3D devm_request_irq(&pdev->dev, ms= i->irq2, rcar_pcie_msi_irq, drivers/pci/host/pcie-xilinx.c: err =3D devm_request_irq(dev, port->irq= , xilinx_pcie_intr_handler, which require the same kind of fix=E2=80=A6 >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. =E2=80=A6 brecause all of them invoke generic_handle_irq() from the req= usted 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. >Bjorn Sebastian