On Sat, Oct 12, 2024 at 08:05:02PM -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 That wasn't particularly helpful. In fact, it gives the impression that the problem is caused by something else, not a bad dequeue. None of the tasks listed in the console log are waiting inside usb_kill_urb(). This time let's see all the enqueues, dequeues, and givebacks for non-control URBs. I don't know that the problem is related to a non-control URB, but I do know that a bunch of control URBs succeed so it might help to keep the focus away from them. 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"; @@ -1301,10 +1301,12 @@ static int dummy_urb_enqueue( dum_hcd->next_frame_urbp = urbp; if (usb_pipetype(urb->pipe) == PIPE_CONTROL) urb->error_count = 1; /* mark as a new urb */ + else + dev_info(dummy_dev(dum_hcd), "Enqueue %p\n", urb); /* 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 +1327,15 @@ 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)) { + if (usb_pipetype(urb->pipe) != PIPE_CONTROL) + dev_info(dummy_dev(dum_hcd), "Dequeue restart %p\n", urb); + hrtimer_start(&dum_hcd->timer, DUMMY_INT_KTIME, + HRTIMER_MODE_REL_SOFT); + } else if (usb_pipetype(urb->pipe) != PIPE_CONTROL) { + dev_info(dummy_dev(dum_hcd), "Dequeue norestart: %d %p\n", + rc, urb); + } spin_unlock_irqrestore(&dum_hcd->dum->lock, flags); return rc; } @@ -1984,6 +1992,8 @@ return_urb: ep->already_seen = ep->setup_stage = 0; usb_hcd_unlink_urb_from_ep(dummy_hcd_to_hcd(dum_hcd), urb); + if (usb_pipetype(urb->pipe) != PIPE_CONTROL) + dev_info(dummy_dev(dum_hcd), "Giveback %p\n", urb); spin_unlock(&dum->lock); usb_hcd_giveback_urb(dummy_hcd_to_hcd(dum_hcd), urb, status); spin_lock(&dum->lock); @@ -1995,8 +2005,7 @@ 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); } @@ -2391,7 +2400,8 @@ 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);
