954c3f8a5f
We need to make sure that the USB serial driver we find matches the USB driver whose probe we are currently executing. Otherwise we will end up with USB serial devices bound to the correct serial driver but wrong USB driver. An example of such cross-probing, where the usbserial_generic USB driver has found the sierra serial driver: May 29 18:26:15 nemi kernel: [ 4442.559246] usbserial_generic 4-4:1.0: Sierra USB modem converter detected May 29 18:26:20 nemi kernel: [ 4447.556747] usbserial_generic 4-4:1.2: Sierra USB modem converter detected May 29 18:26:25 nemi kernel: [ 4452.557288] usbserial_generic 4-4:1.3: Sierra USB modem converter detected sysfs view of the same problem: bjorn@nemi:~$ ls -l /sys/bus/usb/drivers/sierra/ total 0 --w------- 1 root root 4096 May 29 18:23 bind lrwxrwxrwx 1 root root 0 May 29 18:23 module -> ../../../../module/usbserial --w------- 1 root root 4096 May 29 18:23 uevent --w------- 1 root root 4096 May 29 18:23 unbind bjorn@nemi:~$ ls -l /sys/bus/usb-serial/drivers/sierra/ total 0 --w------- 1 root root 4096 May 29 18:23 bind lrwxrwxrwx 1 root root 0 May 29 18:23 module -> ../../../../module/sierra -rw-r--r-- 1 root root 4096 May 29 18:23 new_id lrwxrwxrwx 1 root root 0 May 29 18:32 ttyUSB0 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.0/ttyUSB0 lrwxrwxrwx 1 root root 0 May 29 18:32 ttyUSB1 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.2/ttyUSB1 lrwxrwxrwx 1 root root 0 May 29 18:32 ttyUSB2 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.3/ttyUSB2 --w------- 1 root root 4096 May 29 18:23 uevent --w------- 1 root root 4096 May 29 18:23 unbind bjorn@nemi:~$ ls -l /sys/bus/usb/drivers/usbserial_generic/ total 0 lrwxrwxrwx 1 root root 0 May 29 18:33 4-4:1.0 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.0 lrwxrwxrwx 1 root root 0 May 29 18:33 4-4:1.2 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.2 lrwxrwxrwx 1 root root 0 May 29 18:33 4-4:1.3 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.3 --w------- 1 root root 4096 May 29 18:33 bind lrwxrwxrwx 1 root root 0 May 29 18:33 module -> ../../../../module/usbserial --w------- 1 root root 4096 May 29 18:22 uevent --w------- 1 root root 4096 May 29 18:33 unbind bjorn@nemi:~$ ls -l /sys/bus/usb-serial/drivers/generic/ total 0 --w------- 1 root root 4096 May 29 18:33 bind lrwxrwxrwx 1 root root 0 May 29 18:33 module -> ../../../../module/usbserial -rw-r--r-- 1 root root 4096 May 29 18:33 new_id --w------- 1 root root 4096 May 29 18:22 uevent --w------- 1 root root 4096 May 29 18:33 unbind So we end up with a mismatch between the USB driver and the USB serial driver. The reason for the above is simple: The USB driver probe will succeed if *any* registered serial driver matches, and will use that serial driver for all serial driver functions. This makes ref counting go wrong. We count the USB driver as used, but not the USB serial driver. This may result in Oops'es as demonstrated by Johan Hovold <jhovold@gmail.com>: [11811.646396] drivers/usb/serial/usb-serial.c: get_free_serial 1 [11811.646443] drivers/usb/serial/usb-serial.c: get_free_serial - minor base = 0 [11811.646460] drivers/usb/serial/usb-serial.c: usb_serial_probe - registering ttyUSB0 [11811.646766] usb 6-1: pl2303 converter now attached to ttyUSB0 [11812.264197] USB Serial deregistering driver FTDI USB Serial Device [11812.264865] usbcore: deregistering interface driver ftdi_sio [11812.282180] USB Serial deregistering driver pl2303 [11812.283141] pl2303 ttyUSB0: pl2303 converter now disconnected from ttyUSB0 [11812.283272] usbcore: deregistering interface driver pl2303 [11812.301056] USB Serial deregistering driver generic [11812.301186] usbcore: deregistering interface driver usbserial_generic [11812.301259] drivers/usb/serial/usb-serial.c: usb_serial_disconnect [11812.301823] BUG: unable to handle kernel paging request at f8e7438c [11812.301845] IP: [<f8e38445>] usb_serial_disconnect+0xb5/0x100 [usbserial] [11812.301871] *pde = 357ef067 *pte = 00000000 [11812.301957] Oops: 0000 [#1] PREEMPT SMP [11812.301983] Modules linked in: usbserial(-) [last unloaded: pl2303] [11812.302008] [11812.302019] Pid: 1323, comm: modprobe Tainted: G W 3.4.0-rc7+ #101 Dell Inc. Vostro 1520/0T816J [11812.302115] EIP: 0060:[<f8e38445>] EFLAGS: 00010246 CPU: 1 [11812.302130] EIP is at usb_serial_disconnect+0xb5/0x100 [usbserial] [11812.302141] EAX: f508a180 EBX: f508a180 ECX: 00000000 EDX: f8e74300 [11812.302151] ESI: f5050800 EDI: 00000001 EBP: f5141e78 ESP: f5141e58 [11812.302160] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 [11812.302170] CR0: 8005003b CR2: f8e7438c CR3: 34848000 CR4: 000007d0 [11812.302180] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 [11812.302189] DR6: ffff0ff0 DR7: 00000400 [11812.302199] Process modprobe (pid: 1323, ti=f5140000 task=f61e2bc0 task.ti=f5140000) [11812.302209] Stack: [11812.302216] f8e3be0f f8e3b29c f8e3ae00 00000000 f513641c f5136400 f513641c f507a540 [11812.302325] f5141e98 c133d2c1 00000000 00000000 f509c400 f513641c f507a590 f5136450 [11812.302372] f5141ea8 c12f0344 f513641c f507a590 f5141ebc c12f0c67 00000000 f507a590 [11812.302419] Call Trace: [11812.302439] [<c133d2c1>] usb_unbind_interface+0x51/0x190 [11812.302456] [<c12f0344>] __device_release_driver+0x64/0xb0 [11812.302469] [<c12f0c67>] driver_detach+0x97/0xa0 [11812.302483] [<c12f001c>] bus_remove_driver+0x6c/0xe0 [11812.302500] [<c145938d>] ? __mutex_unlock_slowpath+0xcd/0x140 [11812.302514] [<c12f0ff9>] driver_unregister+0x49/0x80 [11812.302528] [<c1457df6>] ? printk+0x1d/0x1f [11812.302540] [<c133c50d>] usb_deregister+0x5d/0xb0 [11812.302557] [<f8e37c55>] ? usb_serial_deregister+0x45/0x50 [usbserial] [11812.302575] [<f8e37c8d>] usb_serial_deregister_drivers+0x2d/0x40 [usbserial] [11812.302593] [<f8e3a6e2>] usb_serial_generic_deregister+0x12/0x20 [usbserial] [11812.302611] [<f8e3acf0>] usb_serial_exit+0x8/0x32 [usbserial] [11812.302716] [<c1080b48>] sys_delete_module+0x158/0x260 [11812.302730] [<c110594e>] ? mntput+0x1e/0x30 [11812.302746] [<c145c3c3>] ? sysenter_exit+0xf/0x18 [11812.302746] [<c107777c>] ? trace_hardirqs_on_caller+0xec/0x170 [11812.302746] [<c145c390>] sysenter_do_call+0x12/0x36 [11812.302746] Code: 24 02 00 00 e8 dd f3 20 c8 f6 86 74 02 00 00 02 74 b4 8d 86 4c 02 00 00 47 e8 78 55 4b c8 0f b6 43 0e 39 f8 7f a9 8b 53 04 89 d8 <ff> 92 8c 00 00 00 89 d8 e8 0e ff ff ff 8b 45 f0 c7 44 24 04 2f [11812.302746] EIP: [<f8e38445>] usb_serial_disconnect+0xb5/0x100 [usbserial] SS:ESP 0068:f5141e58 [11812.302746] CR2: 00000000f8e7438c Fix by only evaluating serial drivers pointing back to the USB driver we are currently probing. This still allows two or more drivers to match the same device, running their serial driver probes to sort out which one to use. Cc: stable@vger.kernel.org # 3.0, 3.2, 3.3, 3.4 Signed-off-by: Bjørn Mork <bjorn@mork.no> Reviewed-by: Felipe Balbi <balbi@ti.com> Tested-by: Johan Hovold <jhovold@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To understand all the Linux-USB framework, you'll use these resources:
* This source code. This is necessarily an evolving work, and
includes kerneldoc that should help you get a current overview.
("make pdfdocs", and then look at "usb.pdf" for host side and
"gadget.pdf" for peripheral side.) Also, Documentation/usb has
more information.
* The USB 2.0 specification (from www.usb.org), with supplements
such as those for USB OTG and the various device classes.
The USB specification has a good overview chapter, and USB
peripherals conform to the widely known "Chapter 9".
* Chip specifications for USB controllers. Examples include
host controllers (on PCs, servers, and more); peripheral
controllers (in devices with Linux firmware, like printers or
cell phones); and hard-wired peripherals like Ethernet adapters.
* Specifications for other protocols implemented by USB peripheral
functions. Some are vendor-specific; others are vendor-neutral
but just standardized outside of the www.usb.org team.
Here is a list of what each subdirectory here is, and what is contained in
them.
core/ - This is for the core USB host code, including the
usbfs files and the hub class driver ("khubd").
host/ - This is for USB host controller drivers. This
includes UHCI, OHCI, EHCI, and others that might
be used with more specialized "embedded" systems.
gadget/ - This is for USB peripheral controller drivers and
the various gadget drivers which talk to them.
Individual USB driver directories. A new driver should be added to the
first subdirectory in the list below that it fits into.
image/ - This is for still image drivers, like scanners or
digital cameras.
../input/ - This is for any driver that uses the input subsystem,
like keyboard, mice, touchscreens, tablets, etc.
../media/ - This is for multimedia drivers, like video cameras,
radios, and any other drivers that talk to the v4l
subsystem.
../net/ - This is for network drivers.
serial/ - This is for USB to serial drivers.
storage/ - This is for USB mass-storage drivers.
class/ - This is for all USB device drivers that do not fit
into any of the above categories, and work for a range
of USB Class specified devices.
misc/ - This is for all USB device drivers that do not fit
into any of the above categories.