On Thu, 14 May 2015, Petri Gynther wrote: > linux-usb: > > I'm seeing the following recursive locking issue in Linux 3.19 USB stack. > > This happens on every boot on BCM7xxxx (MIPS) STB board with Dell 30" > monitor's built-in USB hub connected to the BCM7xxx USB port. > > I think the problem is: > ehci_irq() > spin_lock_irqsave(&ehci->lock, flags); > ... > if (bh) ehci_work (ehci); > ... > hub_irq() > ehci_urb_enqueue() > intr_submit() > spin_lock_irqsave (&ehci->lock, flags); > > I can't test the 4.1-rc code immediately, but looking at the code, the > same issue is present there. > > Any suggestions on how to fix this? The trick here is that hub_irq() and all the stuff beneath it is supposed to execute in a tasklet, not in the same context as ehci_irq(). Consequently the lock should not be taken recursively. Perhaps your EHCI platform driver has forgotten to include the HCD_BH bit in the .flags member of its hc_driver structure. Which driver are you using? Running "grep EHCI" on the kernel config file should provide the answer. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
