On Mon, 26 Aug 2019, Yoshihiro Shimoda wrote: > Hi Alan, > > > From: Alan Stern, Sent: Saturday, August 24, 2019 12:33 AM > > > > On Fri, 23 Aug 2019, Yoshihiro Shimoda wrote: > > > > > This patch fixes an issue that the following error is > > > possible to happen when ohci hardware causes an interruption > > > and the system is shutting down at the same time. > > > > > > [ 34.851754] usb 2-1: USB disconnect, device number 2 > > > [ 35.166658] irq 156: nobody cared (try booting with the "irqpoll" option) > > > [ 35.173445] CPU: 0 PID: 22 Comm: kworker/0:1 Not tainted 5.3.0-rc5 #85 > > > [ 35.179964] Hardware name: Renesas Salvator-X 2nd version board based on r8a77965 (DT) > > > [ 35.187886] Workqueue: usb_hub_wq hub_event > > > [ 35.192063] Call trace: > > > [ 35.194509] dump_backtrace+0x0/0x150 > > > [ 35.198165] show_stack+0x14/0x20 > > > [ 35.201475] dump_stack+0xa0/0xc4 > > > [ 35.204785] __report_bad_irq+0x34/0xe8 > > > [ 35.208614] note_interrupt+0x2cc/0x318 > > > [ 35.212446] handle_irq_event_percpu+0x5c/0x88 > > > [ 35.216883] handle_irq_event+0x48/0x78 > > > [ 35.220712] handle_fasteoi_irq+0xb4/0x188 > > > [ 35.224802] generic_handle_irq+0x24/0x38 > > > [ 35.228804] __handle_domain_irq+0x5c/0xb0 > > > [ 35.232893] gic_handle_irq+0x58/0xa8 > > > [ 35.236548] el1_irq+0xb8/0x180 > > > [ 35.239681] __do_softirq+0x94/0x23c > > > [ 35.243253] irq_exit+0xd0/0xd8 > > > [ 35.246387] __handle_domain_irq+0x60/0xb0 > > > [ 35.250475] gic_handle_irq+0x58/0xa8 > > > [ 35.254130] el1_irq+0xb8/0x180 > > > [ 35.257268] kernfs_find_ns+0x5c/0x120 > > > [ 35.261010] kernfs_find_and_get_ns+0x3c/0x60 > > > [ 35.265361] sysfs_unmerge_group+0x20/0x68 > > > [ 35.269454] dpm_sysfs_remove+0x2c/0x68 > > > [ 35.273284] device_del+0x80/0x370 > > > [ 35.276683] hid_destroy_device+0x28/0x60 > > > [ 35.280686] usbhid_disconnect+0x4c/0x80 > > > [ 35.284602] usb_unbind_interface+0x6c/0x268 > > > [ 35.288867] device_release_driver_internal+0xe4/0x1b0 > > > [ 35.293998] device_release_driver+0x14/0x20 > > > [ 35.298261] bus_remove_device+0x110/0x128 > > > [ 35.302350] device_del+0x148/0x370 > > > [ 35.305832] usb_disable_device+0x8c/0x1d0 > > > [ 35.309921] usb_disconnect+0xc8/0x2d0 > > > [ 35.313663] hub_event+0x6e0/0x1128 > > > [ 35.317146] process_one_work+0x1e0/0x320 > > > [ 35.321148] worker_thread+0x40/0x450 > > > [ 35.324805] kthread+0x124/0x128 > > > [ 35.328027] ret_from_fork+0x10/0x18 > > > [ 35.331594] handlers: > > > [ 35.333862] [<0000000079300c1d>] usb_hcd_irq > > > [ 35.338126] [<0000000079300c1d>] usb_hcd_irq > > > [ 35.342389] Disabling IRQ #156 > > > > > > The ohci_shutdown() should hold the spin lock while disabling > > > the interruption and changing the rh_state flag. Note that > > > io_watchdog_func() also calls the ohci_shutdown() and it > > > already held the spin lock, so that the patch makes a new > > > function as _ohci_shutdown(). > > > > I don't understand this description. It sounds like the OHCI > > controller generates an interrupt request, and then ohci_shutdown() > > disables the interrupt request before the handler can run. When the > > handler does run, it sees that no interrupts are enabled and so it > > returns IRQ_NOTMINE, leading to the error shown above. > > > > How will holding the spinlock fix this problem? > > I'm sorry for lacking description. I should have described the following > descriptions instead of that. What do you think? > > -- > ohci_shutdown() disables all the interrupt and rh_state is set to > OHCI_RH_HALTED. In other hand, ohci_irq() is possible to enable > OHCI_INTR_SF and OHCI_INTR_MIE on ohci_irq(). Note that OHCI_INTR_SF > is possible to be set by start_ed_unlink() which is called: > ohci_irq() > -> process_done_list() > -> takeback_td() > -> start_ed_unlink() > > So, ohci_irq() has the following condition, the issue happens by > &ohci->regs->intrenable = OHCI_INTR_MIE | OHCI_INTR_SF and > ohci->rh_state = OHCI_RH_HALTED: > > /* interrupt for some other device? */ > if (ints == 0 || unlikely(ohci->rh_state == OHCI_RH_HALTED)) > return IRQ_NOTMINE; > > To fix the issue, ohci_shutdown() holds the spin lock while disabling > the interruption and changing the rh_state flag to prevent reenable > the OHCI_INTR_MIE unexpectedly. Note that io_watchdog_func() also calls > the ohci_shutdown() and it already held the spin lock, so that the patch > makes a new function as _ohci_shutdown(). Okay, that's a lot better. Please resubmit the patch with the new description. Alan Stern
