On Sat, Oct 12, 2024 at 07:10:05PM -0700, syzbot wrote: > Hello, > > syzbot has tested the proposed patch but the reproducer is still triggering an issue: > INFO: task hung in usb_register_dev The console log shows a lot of dequeue failures. Let's find out why they are failing. Alan Stern #syz test: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing Index: usb-devel/drivers/usb/gadget/udc/dummy_hcd.c =================================================================== --- usb-devel.orig/drivers/usb/gadget/udc/dummy_hcd.c +++ usb-devel/drivers/usb/gadget/udc/dummy_hcd.c @@ -50,7 +50,7 @@ #define POWER_BUDGET 500 /* in mA; use 8 for low-power port testing */ #define POWER_BUDGET_3 900 /* in mA */ -#define DUMMY_TIMER_INT_NSECS 125000 /* 1 microframe */ +#define DUMMY_INT_KTIME ns_to_ktime(125000) /* 1 microframe */ static const char driver_name[] = "dummy_hcd"; static const char driver_desc[] = "USB Host+Gadget Emulator"; @@ -276,6 +276,7 @@ struct dummy { unsigned ints_enabled:1; unsigned udc_suspended:1; unsigned pullup:1; + bool alanflag; /* * HOST side support @@ -1304,7 +1305,7 @@ static int dummy_urb_enqueue( /* kick the scheduler, it'll do the rest */ if (!hrtimer_active(&dum_hcd->timer)) - hrtimer_start(&dum_hcd->timer, ns_to_ktime(DUMMY_TIMER_INT_NSECS), + hrtimer_start(&dum_hcd->timer, DUMMY_INT_KTIME, HRTIMER_MODE_REL_SOFT); done: @@ -1325,9 +1326,15 @@ static int dummy_urb_dequeue(struct usb_ rc = usb_hcd_check_unlink_urb(hcd, urb, status); if (!rc && dum_hcd->rh_state != DUMMY_RH_RUNNING && - !list_empty(&dum_hcd->urbp_list)) - hrtimer_start(&dum_hcd->timer, ns_to_ktime(0), HRTIMER_MODE_REL_SOFT); - + !list_empty(&dum_hcd->urbp_list)) { + dum_hcd->dum->alanflag = true; + dev_info(udc_dev(dum_hcd->dum), "Dequeue %p\n", urb); + hrtimer_start(&dum_hcd->timer, DUMMY_INT_KTIME, + HRTIMER_MODE_REL_SOFT); + } else + dev_info(udc_dev(dum_hcd->dum), "Failed dequeue: %d %d %d\n", + rc, dum_hcd->rh_state, + list_empty(&dum_hcd->urbp_list)); spin_unlock_irqrestore(&dum_hcd->dum->lock, flags); return rc; } @@ -1788,6 +1795,7 @@ static enum hrtimer_restart dummy_timer( unsigned long flags; int limit, total; int i; + int alancnt = 0; /* simplistic model for one frame's bandwidth */ /* FIXME: account for transaction and packet overhead */ @@ -1984,6 +1992,9 @@ return_urb: ep->already_seen = ep->setup_stage = 0; usb_hcd_unlink_urb_from_ep(dummy_hcd_to_hcd(dum_hcd), urb); + if (dum->alanflag) + dev_info(udc_dev(dum), "Give back %p\n", urb); + ++alancnt; spin_unlock(&dum->lock); usb_hcd_giveback_urb(dummy_hcd_to_hcd(dum_hcd), urb, status); spin_lock(&dum->lock); @@ -1995,11 +2006,14 @@ return_urb: usb_put_dev(dum_hcd->udev); dum_hcd->udev = NULL; } else if (dum_hcd->rh_state == DUMMY_RH_RUNNING) { - /* want a 1 msec delay here */ - hrtimer_start(&dum_hcd->timer, ns_to_ktime(DUMMY_TIMER_INT_NSECS), + hrtimer_start(&dum_hcd->timer, DUMMY_INT_KTIME, HRTIMER_MODE_REL_SOFT); } + if (dum->alanflag) { + dev_info(udc_dev(dum), "Gave back %d URBs\n", alancnt); + dum->alanflag = false; + } spin_unlock_irqrestore(&dum->lock, flags); return HRTIMER_NORESTART; @@ -2391,7 +2405,8 @@ static int dummy_bus_resume(struct usb_h dum_hcd->rh_state = DUMMY_RH_RUNNING; set_link_state(dum_hcd); if (!list_empty(&dum_hcd->urbp_list)) - hrtimer_start(&dum_hcd->timer, ns_to_ktime(0), HRTIMER_MODE_REL_SOFT); + hrtimer_start(&dum_hcd->timer, DUMMY_INT_KTIME, + HRTIMER_MODE_REL_SOFT); hcd->state = HC_STATE_RUNNING; } spin_unlock_irq(&dum_hcd->dum->lock);
