Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759737AbbKTN7o (ORCPT ); Fri, 20 Nov 2015 08:59:44 -0500 Received: from comal.ext.ti.com ([198.47.26.152]:48163 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754787AbbKTN7l (ORCPT ); Fri, 20 Nov 2015 08:59:41 -0500 From: Grygorii Strashko To: Kishon Vijay Abraham I , Bjorn Helgaas CC: , , , , , Grygorii Strashko , Thomas Gleixner , Sebastian Andrzej Siewior Subject: [PATCH v2] PCI: dra7xx: mark dra7xx_pcie_msi irq as IRQF_NO_THREAD Date: Fri, 20 Nov 2015 15:59:26 +0200 Message-ID: <1448027966-21610-1-git-send-email-grygorii.strashko@ti.com> X-Mailer: git-send-email 2.6.3 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5074 Lines: 106 On -RT, TI DRA7 PCIe driver always produces below backtrace when the first PCI interrupt is triggered: ------------[ cut here ]------------ 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 Modules linked in: ahci_platform(+) ti_vip(+) libahci_platform xhci_pci(+) c_can_platform(+) libahci xhci_hcd ti_vpe c_can libata v4l2_mem2mem can_dev gpio_keys leds_gpio snd_soc_simple_card usbcore spi_ti_qspi videobuf2_core extcon_usb_gpio omap_wdt ti_vpdma videobuf2_dma_contig ti_soc_thermal videobuf2_memops dwc3_omap extcon rtc_omap ov1063x v4l2_common videodev media snd_soc_tlv320aic3x omap_rng rng_core omap_remoteproc CPU: 1 PID: 82 Comm: irq/26-dra7-pci Not tainted 4.1.10-rt10-02638-g6486d7e-dirty #1 Hardware name: Generic DRA74X (Flattened Device Tree) Backtrace: [] (dump_backtrace) from [] (show_stack+0x18/0x1c) r7:c07acca0 r6:00000000 r5:c09034e4 r4:00000000 [] (show_stack) from [] (dump_stack+0x90/0xac) [] (dump_stack) from [] (warn_slowpath_common+0x7c/0xb8) r7:c07acca0 r6:00000096 r5:00000009 r4:ee4d3e38 [] (warn_slowpath_common) from [] (warn_slowpath_fmt+0x38/0x40) r8:ee3fcc00 r7:000001cc r6:00000000 r5:00000002 r4:c07acc78 [] (warn_slowpath_fmt) from [] (handle_irq_event_percpu+0x14c/0x174) r3:000001cc r2:c07acc78 r4:ecfcdd80 [] (handle_irq_event_percpu) from [] (handle_irq_event+0x84/0xb8) r10:00000001 r9:ee4b59c0 r8:ee1d0900 r7:00000001 r6:00000000 r5:ecfcdd80 r4:ee3fcc00 [] (handle_irq_event) from [] (handle_simple_irq+0x90/0x118) r5:ee4a9020 r4:ee3fcc00 [] (handle_simple_irq) from [] (generic_handle_irq+0x30/0x44) r5:ee4a9020 r4:000001cc [] (generic_handle_irq) from [] (dra7xx_pcie_msi_irq_handler+0x7c/0x8c) r5:ee4a9020 r4:00000001 [] (dra7xx_pcie_msi_irq_handler) from [] (irq_forced_thread_fn+0x28/0x5c) r5:ee1d0900 r4:ee4b59c0 [] (irq_forced_thread_fn) from [] (irq_thread+0x128/0x204) r7:00000001 r6:00000000 r5:ee4d2000 r4:ee4b59e4 [] (irq_thread) from [] (kthread+0xd4/0xec) r10:00000000 r9:00000000 r8:00000000 r7:c00870b4 r6:ee4b59c0 r5:ee4b5a00 r4:00000000 [] (kthread) from [] (ret_from_fork+0x14/0x2c) r7:00000000 r6:00000000 r5:c005e228 r4:ee4b5a00 ---[ end trace 0000000000000002 ]--- This backtrace is triggered because dra7xx_pcie_msi_irq_handler() forced to be threaded by default on -RT but, in the same time, it's IRQ dispatcher and calls generic_handle_irq(), which leads to handle_simple_irq() call. The handle_simple_irq() expected to be called with IRQ disabled. The same issue will also happen if kernel will boot with "threadirqs" cmdline parameter (CONFIG_IRQ_FORCED_THREADING). As discussed in [1], the current DRA7 PCIe hw configuration supports 32 interrupts, which cannot change because it's hardwired in silicon, this is a single status read and assuming that only a few (most of the time it will be exactly ONE) of those interrupts are pending at the same time is pretty much a sane assumption. And recommended fix for this issue is to request dra7xx_pcie_msi IRQ with IRQF_NO_THREAD flag. [1] https://lkml.org/lkml/2015/11/3/660 Cc: Thomas Gleixner Cc: Sebastian Andrzej Siewior Signed-off-by: Grygorii Strashko --- Changes in v2: - comment in code truncated Link on v1: https://lkml.org/lkml/2015/11/5/593 drivers/pci/host/pci-dra7xx.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) 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". + */ 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); if (ret) { dev_err(&pdev->dev, "failed to request irq\n"); -- 2.6.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/