Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755341AbbLDSq3 (ORCPT ); Fri, 4 Dec 2015 13:46:29 -0500 Received: from mail.kernel.org ([198.145.29.136]:41923 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751950AbbLDSq0 (ORCPT ); Fri, 4 Dec 2015 13:46:26 -0500 Date: Fri, 4 Dec 2015 12:46:19 -0600 From: Bjorn Helgaas To: Grygorii Strashko Cc: 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 , Sebastian Andrzej Siewior Subject: Re: [PATCH v2] PCI: dra7xx: mark dra7xx_pcie_msi irq as IRQF_NO_THREAD Message-ID: <20151204184619.GD20125@localhost> References: <1448027966-21610-1-git-send-email-grygorii.strashko@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1448027966-21610-1-git-send-email-grygorii.strashko@ti.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6118 Lines: 129 Hi Grygorii, On Fri, Nov 20, 2015 at 03:59:26PM +0200, Grygorii Strashko wrote: > 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 ]--- 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. > 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); 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? 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. Bjorn > if (ret) { > dev_err(&pdev->dev, "failed to request irq\n"); > -- > 2.6.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- 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/