On Mon, 20 Jul 2009, Oliver Neukum wrote: > Am Montag, 20. Juli 2009 09:56:48 schrieb Manuel Lauss: > > Hi Oliver, > > > > While testing a CDC-ACM usb device I encoutered these warnings when > > closing the ttyACM device: > > > > WARNING: at linux-2.6.git/drivers/usb/host/ehci-hcd.c:908 > > ehci_urb_dequeue+0x190/0x198() > > Modules linked in: > > Call Trace: > > [<80107158>] dump_stack+0x8/0x34 > > [<8012a468>] warn_slowpath_common+0x70/0xb0 > > [<802e3968>] ehci_urb_dequeue+0x190/0x198 > > [<802ced70>] usb_hcd_unlink_urb+0xc0/0xf4 > > [<802d0320>] usb_kill_urb+0x54/0xfc > > [<802ec9d8>] acm_port_down+0x21c/0x278 > > [<802ecd94>] acm_tty_close+0x5c/0xb8 > > [<8025f314>] tty_release_dev+0x17c/0x580 > > [<8025f728>] tty_release+0x10/0x20 > > [<8018f078>] __fput+0xf4/0x248 > > [<8018af78>] filp_close+0x68/0x98 > > [<8018b054>] sys_close+0xac/0xd8 > > [<80102260>] stack_done+0x20/0x3c > > This points to an ehci problem. Alan? Yes indeed. This appears to have been caused by a recent change I made. Previously the WARN_ON could never be triggered, but now it can and I didn't realize it. Let me guess: This CDC-ACM device runs at full speed and it is behind a high-speed hub, right? The patch below will certainly remove the warning; the question is whether ehci-hcd will continue to work correctly. Some testing would be appreciated. In particular, try to set up the conditions that would cause the warning, and afterward do "rmmod ehci-hcd". That should cause any remaining errors to surface. Alan Stern Index: usb-2.6/drivers/usb/host/ehci-hcd.c =================================================================== --- usb-2.6.orig/drivers/usb/host/ehci-hcd.c +++ usb-2.6/drivers/usb/host/ehci-hcd.c @@ -903,7 +903,8 @@ static int ehci_urb_dequeue(struct usb_h /* already started */ break; case QH_STATE_IDLE: - WARN_ON(1); + /* QH might be waiting for a Clear-TT-Buffer */ + qh_completions(ehci, qh); break; } break; -- 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
