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Groups > linux.kernel > #1480900 > unrolled thread

Re: crash by cdc_acm driver in kernels 4.8-rc1/5

Started byWim Osterholt <wim@djo.tudelft.nl>
First post2016-09-12 04:50 +0200
Last post2016-09-23 12:10 +0200
Articles 10 — 2 participants

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  Re: crash by cdc_acm driver in kernels 4.8-rc1/5 Wim Osterholt <wim@djo.tudelft.nl> - 2016-09-12 04:50 +0200
    Re: crash by cdc_acm driver in kernels 4.8-rc1/5 Oliver Neukum <oneukum@suse.com> - 2016-09-20 15:20 +0200
      Re: crash by cdc_acm driver in kernels 4.8-rc1/5 Wim Osterholt <wim@djo.tudelft.nl> - 2016-09-20 17:50 +0200
        Re: crash by cdc_acm driver in kernels 4.8-rc1/5 Oliver Neukum <oneukum@suse.com> - 2016-09-21 14:30 +0200
          Re: crash by cdc_acm driver in kernels 4.8-rc1/5 Wim Osterholt <wim@djo.tudelft.nl> - 2016-09-21 18:30 +0200
          Re: crash by cdc_acm driver in kernels 4.8-rc1/5 Wim Osterholt <wim@djo.tudelft.nl> - 2016-09-21 18:50 +0200
            Re: crash by cdc_acm driver in kernels 4.8-rc1/5 Oliver Neukum <oneukum@suse.com> - 2016-09-22 16:50 +0200
              Re: crash by cdc_acm driver in kernels 4.8-rc1/5 Wim Osterholt <wim@djo.tudelft.nl> - 2016-09-22 20:00 +0200
              Re: crash by cdc_acm driver in kernels 4.8-rc1/5 Wim Osterholt <wim@djo.tudelft.nl> - 2016-09-22 21:30 +0200
              Re: crash by cdc_acm driver in kernels 4.8-rc1/5 Wim Osterholt <wim@djo.tudelft.nl> - 2016-09-23 12:10 +0200

#1480900 — Re: crash by cdc_acm driver in kernels 4.8-rc1/5

FromWim Osterholt <wim@djo.tudelft.nl>
Date2016-09-12 04:50 +0200
SubjectRe: crash by cdc_acm driver in kernels 4.8-rc1/5
Message-ID<sgptM-5TD-5@gated-at.bofh.it>
On Thu, Sep 08, 2016 at 03:05:15PM +0200, Oliver Neukum wrote:
> 
> your stack trace is broken. Did you fail to install the System.map file?
> 
> 	Regards
> 		Oliver

A laptop, more broken than the rest, does not output anything after
inserting. Later on it crashes. No system.map file in /boot.
After booting with the dongle inserted it spits out:

[   17.204261] fbcon: radeondrmfb (fb0) is primary device
[   17.276234] BUG: unable to handle kernel NULL pointer dereference at 00000007
[   17.276266] IP: [<d080d2e0>] acm_probe+0x450/0xed0 [cdc_acm]
[   17.276272] *pde = 00000000 
[   17.276278] Oops: 0000 [#1] PREEMPT SMP
[   17.276362] Modules linked in: cdc_acm(+) radeon(+) fbcon i2c_algo_bit bitblit softcursor font drm_kms_helper cfbfillrect syscopyarea cfbimgblt sysfillrect sysimgblt fb_sys_fops cfbcopyarea ttm snd_intel8x0m snd_intel8x0 pcmcia snd_ac97_codec drm dell_smm_hwmon hwmon ipw2200 fb uhci_hcd fbdev ehci_pci yenta_socket ehci_hcd ac97_bus snd_pcm dcdbas libipw usbcore pcmcia_rsrc pcmcia_core snd_timer lib80211 cfg80211 3c59x snd serio_raw intel_agp soundcore usb_common 8250_pci mii video intel_gtt agpgart 8250 8250_base parport_pc parport serial_core
[   17.276371] CPU: 0 PID: 1311 Comm: udevd Not tainted 4.8.0-rc5 #1
[   17.276375] Hardware name: Dell Computer Corporation Inspiron 4100                   /Inspiron 4100            , BIOS A13 05/16/2003
[   17.276379] task: cf9667c0 task.stack: cf10a000
[   17.276385] EIP: 0060:[<d080d2e0>] EFLAGS: 00010202 CPU: 0
[   17.276400] EIP is at acm_probe+0x450/0xed0 [cdc_acm]
[   17.276404] EAX: 00000004 EBX: cbb62800 ECX: 00000040 EDX: 00000040
[   17.276409] ESI: 00000000 EDI: 00000000 EBP: cf10bd00 ESP: cf10bc60
[   17.276413]  DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
[   17.276418] CR0: 80050033 CR2: 00000007 CR3: 0f07f000 CR4: 000006d0
[   17.276420] Stack:
[   17.276435]  00000000 00000082 00000012 00000000 000046dd cf29ac80 cf9e6238 cf90cb84
[   17.276448]  cf801c08 00000012 000045c0 00000080 cf9e6200 cf88d960 00000010 cc884470
[   17.276462]  cc884400 00000001 cf194a00 cf193000 cf194a00 c14f00ff cc8844f8 cf9667c0
[   17.276464] Call Trace:
[   17.276486]  [<c14f00ff>] ? _raw_spin_unlock_irqrestore+0xf/0x30
[   17.276498]  [<c106d139>] ? preempt_count_add+0x89/0x90
[   17.276505]  [<c106d139>] ? preempt_count_add+0x89/0x90
[   17.276512]  [<c14f02f1>] ? _raw_spin_lock_irqsave+0x11/0x40
[   17.276611]  [<d0b144cc>] ? usb_probe_interface+0xfc/0x2d0 [usbcore]
[   17.276657]  [<d0b144cc>] ? usb_probe_interface+0xfc/0x2d0 [usbcore]
[   17.276675]  [<c1317aef>] ? driver_probe_device+0x1ff/0x400
[   17.276682]  [<c1317aef>] ? driver_probe_device+0x1ff/0x400
[   17.276691]  [<c1317dc9>] ? __driver_attach+0xd9/0x100
[   17.276698]  [<c1317dc9>] ? __driver_attach+0xd9/0x100
[   17.276706]  [<c14f02bd>] ? _raw_spin_lock+0xd/0x30
[   17.276712]  [<c14f00cd>] ? _raw_spin_unlock+0xd/0x30
[   17.276720]  [<c1317cf0>] ? driver_probe_device+0x400/0x400
[   17.276728]  [<c1315ca7>] ? bus_for_each_dev+0x47/0x80
[   17.276735]  [<c1315ca7>] ? bus_for_each_dev+0x47/0x80
[   17.276743]  [<c1317441>] ? driver_attach+0x11/0x20
[   17.276750]  [<c1317cf0>] ? driver_probe_device+0x400/0x400
[   17.276757]  [<c1316f9f>] ? bus_add_driver+0x1df/0x270
[   17.276764]  [<c14f00cd>] ? _raw_spin_unlock+0xd/0x30
[   17.276777]  [<c126c714>] ? kset_find_obj+0x44/0x90
[   17.276785]  [<c131874e>] ? driver_register+0x4e/0xc0
[   17.276791]  [<c131874e>] ? driver_register+0x4e/0xc0
[   17.276837]  [<d0b1330a>] ? usb_register_driver+0x5a/0x110 [usbcore]
[   17.276852]  [<d07f90a7>] ? acm_init+0xa7/0xd6 [cdc_acm]
[   17.276857]  [<d07f9000>] ? 0xd07f9000
[   17.276864]  [<c100048d>] ? do_one_initcall+0x2d/0x130
[   17.276880]  [<c10f56c9>] ? do_init_module+0x19/0x1a0
[   17.276889]  [<c10f56f8>] ? do_init_module+0x48/0x1a0
[   17.276900]  [<c10b7cc7>] ? load_module+0x19c7/0x2150
[   17.276913]  [<c113ef33>] ? kernel_read_file+0x103/0x200
[   17.276922]  [<c10b85f0>] ? SyS_finit_module+0x90/0xd0
[   17.276929]  [<c10b85f0>] ? SyS_finit_module+0x90/0xd0
[   17.276940]  [<c10016c8>] ? do_int80_syscall_32+0x38/0x90
[   17.276946]  [<c10016c8>] ? do_int80_syscall_32+0x38/0x90
[   17.276954]  [<c14f07da>] ? entry_INT80_32+0x2a/0x2a
[   17.277046] Code: 04 89 b3 c0 04 00 00 8d 04 80 c1 e0 02 89 83 b4 04 00 00 8b 45 a8 89 43 04 8b 45 ac 89 43 08 8b 45 a0 89 03 8b 45 c0 85 c0 74 0a <0f> b6 40 03 89 83 c8 04 00 00 f6 45 a4 04 74 07 83 a3 c8 04 00
[   17.277065] EIP: [<d080d2e0>] acm_probe+0x450/0xed0 [cdc_acm] SS:ESP 0068:cf10bc60
[   17.277068] CR2: 0000000000000007
[   17.277360] ---[ end trace 5847748dfb454f14 ]---
[   17.280317] udevd[1295]: worker [1311] terminated by signal 9 (Killed)
[   17.280333] udevd[1295]: worker [1311] failed while handling '/devices/pci0000:00/0000:00:1d.0/usb1/1-1/1-1:1.0'

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#1487335

FromOliver Neukum <oneukum@suse.com>
Date2016-09-20 15:20 +0200
Message-ID<sjt7P-3qP-19@gated-at.bofh.it>
In reply to#1480900
On Mon, 2016-09-12 at 04:43 +0200, Wim Osterholt wrote:
> 
> A laptop, more broken than the rest, does not output anything after
> inserting. Later on it crashes. No system.map file in /boot.
> After booting with the dongle inserted it spits out:

I cannot replicate it. Could you please provide "lsusb -v"?

	Regards
		Oliver

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#1487447

FromWim Osterholt <wim@djo.tudelft.nl>
Date2016-09-20 17:50 +0200
Message-ID<sjvsZ-4Ti-1@gated-at.bofh.it>
In reply to#1487335
On Tue, Sep 20, 2016 at 03:05:14PM +0200, Oliver Neukum wrote:
> 
> I cannot replicate it. Could you please provide "lsusb -v"?
> 
> 	Regards
> 		Oliver

It concerns these type of modems:
http://www.ebay.nl/itm/191933738340
http://www.ebay.nl/itm/121590899044

lsusb:
Bus 002 Device 002: ID 0bda:0111 Realtek Semiconductor Corp. RTS5111 Card Reader Controller
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 008 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 007 Device 002: ID 0572:1340 Conexant Systems (Rockwell), Inc. 
Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 002: ID 0fe6:9700 Kontron (Industrial Computer Source / ICS Advent) DM9601 Fast Ethernet Adapter
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

Since the output is quite lengthy, I've cut out everything but Bus 007 Device 002
lsusb -v:

Bus 007 Device 002: ID 0572:1340 Conexant Systems (Rockwell), Inc. 
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               1.10
  bDeviceClass            2 Communications
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  idVendor           0x0572 Conexant Systems (Rockwell), Inc.
  idProduct          0x1340 
  bcdDevice            1.00
  iManufacturer           1 Conexant
  iProduct                2 USB Modem
  iSerial                 3 12345678
  bNumConfigurations      2
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           73
    bNumInterfaces          2
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              100mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         2 Communications
      bInterfaceSubClass      2 Abstract (modem)
      bInterfaceProtocol      1 AT-commands (v.25ter)
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval             128
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass        10 CDC Data
      bInterfaceSubClass      0 Unused
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x82  EP 2 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               1
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x02  EP 2 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               1
      CDC Header:
        bcdCDC               1.10
      CDC Call Management:
        bmCapabilities       0x03
          call management
          use DataInterface
        bDataInterface          1
      CDC ACM:
        bmCapabilities       0x07
          sends break
          line coding and serial state
          get/set/clear comm features
      CDC Union:
        bMasterInterface        0
        bSlaveInterface         1 
      Country Selection:
        iCountryCodeRelDate        4 04052004
        wCountryCode          0x4803
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           96
    bNumInterfaces          3
    bConfigurationValue     2
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              100mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         2 Communications
      bInterfaceSubClass      2 Abstract (modem)
      bInterfaceProtocol      1 AT-commands (v.25ter)
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval             128
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass        10 CDC Data
      bInterfaceSubClass      0 Unused
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x82  EP 2 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval              10
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x02  EP 2 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval              10
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass        10 CDC Data
      bInterfaceSubClass      0 Unused
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x83  EP 3 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               1
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x03  EP 3 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               1
      CDC Header:
        bcdCDC               1.10
      CDC Call Management:
        bmCapabilities       0x03
          call management
          use DataInterface
        bDataInterface          1
      CDC ACM:
        bmCapabilities       0x07
          sends break
          line coding and serial state
          get/set/clear comm features
      CDC Union:
        bMasterInterface        0
        bSlaveInterface         1 
      Country Selection:
        iCountryCodeRelDate        4 04052004
        wCountryCode          0x4803
Device Status:     0x0000
  (Bus Powered)


Regards Wim.

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#1488073

FromOliver Neukum <oneukum@suse.com>
Date2016-09-21 14:30 +0200
Message-ID<sjOOZ-vu-1@gated-at.bofh.it>
In reply to#1487447
On Tue, 2016-09-20 at 17:45 +0200, Wim Osterholt wrote:
> On Tue, Sep 20, 2016 at 03:05:14PM +0200, Oliver Neukum wrote:
> > 
> > I cannot replicate it. Could you please provide "lsusb -v"?
> > 
> > 	Regards
> > 		Oliver
> 
> It concerns these type of modems:
> http://www.ebay.nl/itm/191933738340
> http://www.ebay.nl/itm/121590899044

OK. These devices are unusual in having two outputs.
I've ordered a device, but it will take weeks to ship.
It is definitely valuable for testing.

Anyway, which of its configurations is used?
Please look up the bConfigurationValue for your device
in sysfs.

	Regards
		Oliver

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#1488247

FromWim Osterholt <wim@djo.tudelft.nl>
Date2016-09-21 18:30 +0200
Message-ID<sjSzf-2R4-9@gated-at.bofh.it>
In reply to#1488073
On Wed, Sep 21, 2016 at 02:21:17PM +0200, Oliver Neukum wrote:
> On Tue, 2016-09-20 at 17:45 +0200, Wim Osterholt wrote:
> 
> Anyway, which of its configurations is used?
> Please look up the bConfigurationValue for your device
> in sysfs.

And what might that be?
'locate sysfs' gives one hit at /etc/init.d/sysfs
When I say 'sysfs stop' it stops udev.
When I say 'sysfs start' it says nothing.
Again 'sysfs start' says sysfs already started.
That doesn't have changed anything.

There's a /sys/fs/ext4/* with nothing that you seem to mean.

There's a /proc/sys/fs with nothing that you seem to mean.

There's one mention of acm in /proc/tty/drivers and nowhere I see anything
that might be of any interest somehow.


Regards, Wim.


----- wim@djo.tudelft.nl -----

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#1488270

FromWim Osterholt <wim@djo.tudelft.nl>
Date2016-09-21 18:50 +0200
Message-ID<sjSSC-2Xx-19@gated-at.bofh.it>
In reply to#1488073
On Wed, Sep 21, 2016 at 02:21:17PM +0200, Oliver Neukum wrote:
> in sysfs.

Google pointed me to /sys/bus/usb/drivers/usb/*
where I find all kinds of 'bConfigurationValue'.
Now is the problem to find which one you could mean.

Under /sys/bus/usb/drivers/usb/7-1  I find
manufacturer  which reads 'Conexant'  and
bConfigurationValue  which reads '1'


Regards, Wim.

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#1488952

FromOliver Neukum <oneukum@suse.com>
Date2016-09-22 16:50 +0200
Message-ID<skdu2-7CL-23@gated-at.bofh.it>
In reply to#1488270
On Wed, 2016-09-21 at 18:41 +0200, Wim Osterholt wrote:
> On Wed, Sep 21, 2016 at 02:21:17PM +0200, Oliver Neukum wrote:
> > in sysfs.
> 
> Google pointed me to /sys/bus/usb/drivers/usb/*
> where I find all kinds of 'bConfigurationValue'.
> Now is the problem to find which one you could mean.
> 
> Under /sys/bus/usb/drivers/usb/7-1  I find
> manufacturer  which reads 'Conexant'  and
> bConfigurationValue  which reads '1'

OK. Strange. Please do

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.

	Regards
		Oliver

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#1489235

FromWim Osterholt <wim@djo.tudelft.nl>
Date2016-09-22 20:00 +0200
Message-ID<skgrU-10r-43@gated-at.bofh.it>
In reply to#1488952

> >Please look up the bConfigurationValue for your device
> >in sysfs.

I didn't explicitly say that this was done under kernel-4.7.4, otherwise
it may have been impossible under 4.8 .

On Thu, Sep 22, 2016 at 04:40:50PM +0200, Oliver Neukum wrote:
> 
> OK. Strange. Please do
> 
> 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.

You don't state if this must be done in a safe 4.7.4 or a crashable 4.8.
(if I get that far to retrieve dmesg to a file).

Anyway, echo "module cdc_acm +mpf" > /sys/kernel/debug/dynamic_debug/control
results in 'No such file or directory' because there is no 'dynamic_debug'.

The kernel option DYNAMIC_DEBUG was not set.
A new kernel is compiling now..



Groeten, Wim.

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#1489481

FromWim Osterholt <wim@djo.tudelft.nl>
Date2016-09-22 21:30 +0200
Message-ID<skhR0-1Z0-39@gated-at.bofh.it>
In reply to#1488952
On Thu, Sep 22, 2016 at 04:40:50PM +0200, Oliver Neukum wrote:
> OK. Strange. Please do
> 
> 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.

On kernel-4.7.4 this gives this little output:

[  135.279989] sysrq: SysRq : Changing Loglevel
[  135.280489] sysrq: Loglevel set to 9
[  146.712004] usbcore: registered new interface driver cdc_acm
[  146.712537] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters
[  173.257346] usb 6-1: new full-speed USB device number 2 using uhci_hcd
[  173.450326] usb 6-1: New USB device found, idVendor=0572, idProduct=1340
[  173.450879] usb 6-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  173.451374] usb 6-1: Product: USB Modem
[  173.451867] usb 6-1: Manufacturer: Conexant
[  173.452360] usb 6-1: SerialNumber: 12345678
[  173.455415] cdc_acm:acm_probe: cdc_acm 6-1:1.0: interfaces are valid
[  173.455995] cdc_acm 6-1:1.0: ttyACM0: USB ACM device
[  173.562316] cdc_acm:acm_ctrl_msg: cdc_acm 6-1:1.0: acm_ctrl_msg - rq 0x20, val 0x0, len 0x7, result 7


4.8-rc7 is compiling now..


Regards, Wim.

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#1489915

FromWim Osterholt <wim@djo.tudelft.nl>
Date2016-09-23 12:10 +0200
Message-ID<skvAB-2j1-9@gated-at.bofh.it>
In reply to#1488952
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.

That is not possible under a 4.8 kernel.

'Fixing recursive fault but reboot is needed!' and frozen it is.


Regards, Wim.

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