On Tue, 28 Jul 2015, Laura Abbott wrote: > Hi, > > While debugging an issue with another driver, I've hit some corruption in xHCI. > I'm not sure if the corruption is directly caused by the first warning or if > the warning is exposing an issue with the driver. The issue I was actually > trying to debug was a URB double submit: > > ------------[ cut here ]------------ > WARNING: CPU: 3 PID: 3563 at drivers/usb/core/urb.c:339 usb_submit_urb+0x2ad/0x5a0() > URB ffff8804078ac240 submitted while active ... > I've found several issues where a double submit can happen so I mostly have > a handle on that. Shortly after the double submit though, I see corruption: > > ------------[ cut here ]------------ > WARNING: CPU: 3 PID: 0 at lib/list_debug.c:36 __list_add+0xb4/0xc0() > list_add double add: new=ffff8804078ac260, prev=ffff8804078ac260, next=ffff88040456c358. > which will repeat itself until the kernel GPFs or crashes somewhere > else. The test case for reproducing this is sending commands to the > USB driver very rapidly so the double submit is happening fairly > frequently. Is this a case where the driver is very questionable so > all bets are off or is this an issue in the xHCI layer? I've never > seen any other double submit reports indicating this type of corruption. It's fair to say that once a double-submit error occurs, all bets are off. 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
