On Tue, 2016-09-27 at 18:34 +0200, Wim Osterholt wrote: > On Thu, Sep 22, 2016 at 04:40:50PM +0200, Oliver Neukum wrote: > > > > dmesg -c > > echo 9 > /proc/sysrq-trigger > > modprobe cdc_acm > > echo "module cdc_acm +mpf" > /sys/kernel/debug/dynamic_debug/control > > > > [plug your device in] > > > > and provide the full output of dmesg after that. > > After some experimenting I succeeded in grabbing it over the serial port. > The console was immedately frozen, but the serial port kept working: Very good. This is a valid oops. We can do two things. When I decode it, seems to crash in acm_alloc_minor() which does not make sense. It is likely that our kernels or compilers are a bit different. Could you please call gdb on your kernel module cdc-acm.ko and do: list *(acm_probe+0x4ee) this should show you where it crashes. In addition I've attached a patch with paranoid debugging. Could you compile and test a kernel with it? Regards Oliver
From 28bb525ab295bd014768868eafb6a76d0c0d80c2 Mon Sep 17 00:00:00 2001 From: Oliver Neukum <oneukum@xxxxxxxx> Date: Wed, 28 Sep 2016 11:11:04 +0200 Subject: [PATCH] CDC-ACM: more paranoid debugging --- drivers/usb/class/cdc-acm.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 78f0f85..283e16e 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -1324,10 +1324,13 @@ made_compressed_probe: if (minor < 0) goto alloc_fail1; + WARN_ON(!epctrl); ctrlsize = usb_endpoint_maxp(epctrl); + WARN_ON(!epread); readsize = usb_endpoint_maxp(epread) * (quirks == SINGLE_RX_URB ? 1 : 2); acm->combined_interfaces = combined_interfaces; + WARN_ON(!epwrite); acm->writesize = usb_endpoint_maxp(epwrite) * 20; acm->control = control_interface; acm->data = data_interface; @@ -1352,6 +1355,7 @@ made_compressed_probe: acm->port.ops = &acm_port_ops; init_usb_anchor(&acm->delayed); acm->quirks = quirks; + dev_dbg(&intf->dev, "control structures set up\n"); buf = usb_alloc_coherent(usb_dev, ctrlsize, GFP_KERNEL, &acm->ctrl_dma); if (!buf) -- 2.6.2
