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: > [<c0013060>] (dump_backtrace) from [<c0013280>] (show_stack+0x18/0x1c) > r7:c07acca0 r6:00000000 r5:c09034e4 r4:00000000 > [<c0013268>] (show_stack) from [<c061ef14>] (dump_stack+0x90/0xac) > [<c061ee84>] (dump_stack) from [<c00436e4>] (warn_slowpath_common+0x7c/0xb8) > r7:c07acca0 r6:00000096 r5:00000009 r4:ee4d3e38 > [<c0043668>] (warn_slowpath_common) from [<c0043758>] (warn_slowpath_fmt+0x38/0x40) > r8:ee3fcc00 r7:000001cc r6:00000000 r5:00000002 r4:c07acc78 > [<c0043724>] (warn_slowpath_fmt) from [<c0085fd0>] (handle_irq_event_percpu+0x14c/0x174) > r3:000001cc r2:c07acc78 > r4:ecfcdd80 > [<c0085e84>] (handle_irq_event_percpu) from [<c008607c>] (handle_irq_event+0x84/0xb8) > r10:00000001 r9:ee4b59c0 r8:ee1d0900 r7:00000001 r6:00000000 r5:ecfcdd80 > r4:ee3fcc00 > [<c0085ff8>] (handle_irq_event) from [<c0089240>] (handle_simple_irq+0x90/0x118) > r5:ee4a9020 r4:ee3fcc00 > [<c00891b0>] (handle_simple_irq) from [<c0085514>] (generic_handle_irq+0x30/0x44) > r5:ee4a9020 r4:000001cc > [<c00854e4>] (generic_handle_irq) from [<c034a7d4>] (dra7xx_pcie_msi_irq_handler+0x7c/0x8c) > r5:ee4a9020 r4:00000001 > [<c034a758>] (dra7xx_pcie_msi_irq_handler) from [<c0086f08>] (irq_forced_thread_fn+0x28/0x5c) > r5:ee1d0900 r4:ee4b59c0 > [<c0086ee0>] (irq_forced_thread_fn) from [<c00871dc>] (irq_thread+0x128/0x204) > r7:00000001 r6:00000000 r5:ee4d2000 r4:ee4b59e4 > [<c00870b4>] (irq_thread) from [<c005e2fc>] (kthread+0xd4/0xec) > r10:00000000 r9:00000000 r8:00000000 r7:c00870b4 r6:ee4b59c0 r5:ee4b5a00 > r4:00000000 > [<c005e228>] (kthread) from [<c000faa8>] (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 <tglx@xxxxxxxxxxxxx> > Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> > Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx> > --- > 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@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
