linux-3.9.3 - hit limit of 255 usb->serial devices

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* linux-3.9.3 - hit limit of 255 usb->serial devices
@ 2013-05-24 13:56 Tobias Winter
  2013-05-24 17:23 ` Greg KH
  0 siblings, 1 reply; 13+ messages in thread
From: Tobias Winter @ 2013-05-24 13:56 UTC (permalink / raw)
  To: linux-serial

[-- Attachment #1: Type: text/plain, Size: 4585 bytes --]

Hi there,

since my propblem is with usb to serial adapters I was unsure if this is
the right place. If not, please let me know.

After equipping a server with a lot of ftdi singleport usb2serial
devices, I ran into a serial device limit that is included in
include/linux/usb/serial.h .

The limit of devices seems to be 255, resulting in ttyUSB254 to be the
last supported device.

The codesnippet in question is:

#define SERIAL_TTY_MINORS 254 /* loads of devices :) */
#define SERIAL_TTY_NO_MINOR 255 /* No minor was assigned */

I successfully modified it to support 256 devices and fail gracefully
afterward:

#define SERIAL_TTY_MINORS 256 /* loads of devices :) */
#define SERIAL_TTY_NO_MINOR 255 /* No minor was assigned */

That results in the following dmesg output:

[..]
usb 1-8.4.4.4.3: Detected FT232BM
usb 1-8.4.4.4.3: Number of endpoints 2
usb 1-8.4.4.4.3: Endpoint 1 MaxPacketSize 64
usb 1-8.4.4.4.3: Endpoint 2 MaxPacketSize 64
usb 1-8.4.4.4.3: Setting MaxPacketSize 64
usb 1-8.4.4.4.3: FTDI USB Serial Device converter now attached to ttyUSB254
hub 1-8.4.4.4:1.0: port 4, status 0101, change 0000, 12 Mb/s
usb 1-8.4.4.4.4: new full-speed USB device number 91 using ehci-pci
usb 1-8.4.4.4.4: ep0 maxpacket = 8
usb 1-8.4.4.4.4: default language 0x0409
usb 1-8.4.4.4.4: udev 91, busnum 1, minor = 90
usb 1-8.4.4.4.4: New USB device found, idVendor=0403, idProduct=6001
usb 1-8.4.4.4.4: New USB device strings: Mfr=1, Product=2, SerialNumber=0
usb 1-8.4.4.4.4: Product: USB <-> Serial
usb 1-8.4.4.4.4: Manufacturer: FTDI
usb 1-8.4.4.4.4: usb_probe_device
usb 1-8.4.4.4.4: configuration #1 chosen from 1 choice
usb 1-8.4.4.4.4: adding 1-8.4.4.4.4:1.0 (config #1, interface 0)
ftdi_sio 1-8.4.4.4.4:1.0: usb_probe_interface
ftdi_sio 1-8.4.4.4.4:1.0: usb_probe_interface - got id
ftdi_sio 1-8.4.4.4.4:1.0: FTDI USB Serial Device converter detected
usb 1-8.4.4.4.4: Detected FT232BM
usb 1-8.4.4.4.4: Number of endpoints 2
usb 1-8.4.4.4.4: Endpoint 1 MaxPacketSize 64
usb 1-8.4.4.4.4: Endpoint 2 MaxPacketSize 64
usb 1-8.4.4.4.4: Setting MaxPacketSize 64
usb 1-8.4.4.4.4: FTDI USB Serial Device converter now attached to ttyUSB255

If any further devices are connected, I get the expected error that no
more free sedrial devices are there.

hub 4-1.1:1.0: state 7 ports 4 chg 001e evt 0000
hub 4-1.1:1.0: port 1, status 0101, change 0000, 12 Mb/s
usb 4-1.1.1: new full-speed USB device number 89 using uhci_hcd
usb 4-1.1.1: ep0 maxpacket = 8
usb 4-1.1.1: default language 0x0409
usb 4-1.1.1: udev 89, busnum 4, minor = 472
usb 4-1.1.1: New USB device found, idVendor=0403, idProduct=6001
usb 4-1.1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 4-1.1.1: Product: FT232R USB UART
usb 4-1.1.1: Manufacturer: FTDI
usb 4-1.1.1: SerialNumber: A500EG03
usb 4-1.1.1: usb_probe_device
usb 4-1.1.1: configuration #1 chosen from 1 choice
usb 4-1.1.1: adding 4-1.1.1:1.0 (config #1, interface 0)
ftdi_sio 4-1.1.1:1.0: usb_probe_interface
ftdi_sio 4-1.1.1:1.0: usb_probe_interface - got id
ftdi_sio 4-1.1.1:1.0: FTDI USB Serial Device converter detected
ftdi_sio 4-1.1.1:1.0: No more free serial devices
ftdi_sio: probe of 4-1.1.1:1.0 failed with error -5
hub 4-1.1:1.0: port 2, status 0101, change 0000, 12 Mb/s
usb 4-1.1.2: new full-speed USB device number 90 using uhci_hcd
usb 4-1.1.2: ep0 maxpacket = 8
usb 4-1.1.2: default language 0x0409
usb 4-1.1.2: udev 90, busnum 4, minor = 473
usb 4-1.1.2: New USB device found, idVendor=0403, idProduct=6001
usb 4-1.1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 4-1.1.2: Product: FT232R USB UART
usb 4-1.1.2: Manufacturer: FTDI
usb 4-1.1.2: SerialNumber: A500EG07
usb 4-1.1.2: usb_probe_device
usb 4-1.1.2: configuration #1 chosen from 1 choice
usb 4-1.1.2: adding 4-1.1.2:1.0 (config #1, interface 0)
ftdi_sio 4-1.1.2:1.0: usb_probe_interface
ftdi_sio 4-1.1.2:1.0: usb_probe_interface - got id
ftdi_sio 4-1.1.2:1.0: FTDI USB Serial Device converter detected
ftdi_sio 4-1.1.2:1.0: No more free serial devices
ftdi_sio: probe of 4-1.1.2:1.0 failed with error -5

and so on.

Output of `lsusb | sort` with 256 usb2serial devices connected:
http://pastebin.com/wqrYUbwZ

In case you end up agreeing with me that there are no reasons to limit
the devices to 255, would you be inclined to fix this in the main kernel
tree? Do I have to open up a bug somewhere?

I also tried increasing the numbers further but I run into rollover
issues as the kernel tries to reassign ttyUSB0 ttyUSB1 which is already
taken. It seems without some other modification 256 devices is the limit?

Thanks for your efforts!

Tobias

[-- Attachment #2: lsusb_sorted.txt --]
[-- Type: text/plain, Size: 33132 bytes --]

Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 006: ID 058f:6254 Alcor Micro Corp. USB Hub
Bus 001 Device 007: ID 0451:2046 Texas Instruments, Inc. TUSB2046 Hub
Bus 001 Device 008: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 009: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 010: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 011: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 012: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 013: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 014: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 015: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 016: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 017: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 018: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 019: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 020: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 021: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 022: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 023: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 024: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 025: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 026: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 027: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 001 Device 028: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 029: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 030: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 031: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 032: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 033: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 034: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 035: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 036: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 037: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 038: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 039: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 040: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 041: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 042: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 043: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 044: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 045: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 046: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 047: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 048: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 049: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 050: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 051: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 052: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 053: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 054: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 055: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 056: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 057: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 058: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 059: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 060: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 061: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 062: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 063: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 064: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 065: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 066: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 067: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 068: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 069: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 070: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 071: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 072: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 073: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 074: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 075: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 076: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 077: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 078: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 079: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 080: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 081: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 082: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 083: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 084: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 085: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 086: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 087: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 088: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 089: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 090: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 001 Device 091: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 002: ID 0451:2046 Texas Instruments, Inc. TUSB2046 Hub
Bus 002 Device 003: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 004: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 005: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 006: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 007: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 008: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 009: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 010: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 011: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 012: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 013: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 014: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 015: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 016: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 017: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 018: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 019: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 020: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 021: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 022: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 002 Device 023: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 024: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 025: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 026: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 027: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 028: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 029: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 030: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 031: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 032: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 033: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 034: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 035: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 036: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 037: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 038: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 039: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 040: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 041: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 042: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 043: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 044: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 045: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 046: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 047: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 048: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 049: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 050: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 051: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 052: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 053: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 054: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 055: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 056: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 057: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 058: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 059: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 060: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 061: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 062: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 063: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 064: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 065: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 066: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 067: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 068: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 069: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 070: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 071: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 072: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 073: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 074: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 075: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 076: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 077: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 078: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 079: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 080: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 081: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 082: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 083: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 084: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 085: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 086: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 002: ID 413c:1003 Dell Computer Corp. Keyboard Hub
Bus 003 Device 003: ID 0451:2046 Texas Instruments, Inc. TUSB2046 Hub
Bus 003 Device 004: ID 413c:2010 Dell Computer Corp. Keyboard
Bus 003 Device 005: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 006: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 007: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 008: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 009: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 010: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 011: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 012: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 013: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 014: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 015: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 016: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 017: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 018: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 019: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 020: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 021: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 022: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 023: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 024: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 003 Device 025: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 026: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 027: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 028: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 029: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 030: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 031: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 032: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 033: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 034: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 035: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 036: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 037: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 038: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 039: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 040: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 041: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 042: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 043: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 044: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 045: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 046: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 047: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 048: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 049: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 050: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 051: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 052: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 053: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 054: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 055: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 056: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 057: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 058: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 059: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 060: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 061: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 062: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 063: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 064: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 065: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 066: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 067: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 068: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 069: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 070: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 071: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 072: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 073: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 074: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 075: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 076: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 077: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 078: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 079: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 080: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 081: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 082: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 083: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 084: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 085: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 086: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 087: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 088: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 002: ID 0451:2046 Texas Instruments, Inc. TUSB2046 Hub
Bus 004 Device 003: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 004: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 005: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 006: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 007: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 008: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 009: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 010: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 011: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 012: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 013: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 014: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 015: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 016: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 017: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 018: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 019: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 020: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 021: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 022: ID 03eb:3301 Atmel Corp. at43301 4-Port Hub
Bus 004 Device 023: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 024: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 025: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 026: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 027: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 028: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 029: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 030: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 031: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 032: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 033: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 034: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 035: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 036: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 037: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 038: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 039: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 040: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 041: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 042: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 043: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 044: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 045: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 046: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 047: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 048: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 049: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 050: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 051: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 052: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 053: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 054: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 055: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 056: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 057: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 058: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 059: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 060: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 061: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 062: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 063: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 064: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 065: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 066: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 067: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 068: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 069: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 070: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 071: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 072: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 073: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 074: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 075: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 076: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 077: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 078: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 079: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 080: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 081: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 082: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 083: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 084: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 085: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 004 Device 086: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

[-- Attachment #3: kern.log.bz2 --]
[-- Type: application/octet-stream, Size: 18433 bytes --]

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: linux-3.9.3 - hit limit of 255 usb->serial devices
  2013-05-24 13:56 linux-3.9.3 - hit limit of 255 usb->serial devices Tobias Winter
@ 2013-05-24 17:23 ` Greg KH
  2013-05-27  9:30   ` [PATCH] Raise the maximum number of usb-serial devices to 256 Tobias Winter
  0 siblings, 1 reply; 13+ messages in thread
From: Greg KH @ 2013-05-24 17:23 UTC (permalink / raw)
  To: Tobias Winter; +Cc: linux-serial, linux-usb

On Fri, May 24, 2013 at 03:56:37PM +0200, Tobias Winter wrote:
> Hi there,
> 
> since my propblem is with usb to serial adapters I was unsure if this is
> the right place. If not, please let me know.

Not really, linux-usb@ is the proper one, I've included that on the cc:

> After equipping a server with a lot of ftdi singleport usb2serial
> devices, I ran into a serial device limit that is included in
> include/linux/usb/serial.h .
> 
> The limit of devices seems to be 255, resulting in ttyUSB254 to be the
> last supported device.
> 
> The codesnippet in question is:
> 
> #define SERIAL_TTY_MINORS 254 /* loads of devices :) */
> #define SERIAL_TTY_NO_MINOR 255 /* No minor was assigned */

Yes, that's the limit of usb-serial devices in the system at the moment.
In 10+ years, no one has complained yet, so it's been a good number :)

> Output of `lsusb | sort` with 256 usb2serial devices connected:
> http://pastebin.com/wqrYUbwZ

Nice job.

> In case you end up agreeing with me that there are no reasons to limit
> the devices to 255, would you be inclined to fix this in the main kernel
> tree? Do I have to open up a bug somewhere?

You can send a patch making the number dynamic, that would be great to
have.

> I also tried increasing the numbers further but I run into rollover
> issues as the kernel tries to reassign ttyUSB0 ttyUSB1 which is already
> taken. It seems without some other modification 256 devices is the limit?

Yes, there might be some limits in the tty layer as well for only 256
tty devices, but I haven't looked there in a long time, perhaps that is
now no longer the case.

> Bus 001 Device 091: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC

I'm just glad to see we can support 91 different devices on a single
root hub, that's good to see, as I don't think anyone has tested that in
a very long time :)

thanks,

greg k-h

^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH] Raise the maximum number of usb-serial devices to 256
  2013-05-24 17:23 ` Greg KH
@ 2013-05-27  9:30   ` Tobias Winter
  2013-05-28  6:17     ` Rob Landley
       [not found]     ` <87obbwbo8s.fsf@nemi.mork.no>
  0 siblings, 2 replies; 13+ messages in thread
From: Tobias Winter @ 2013-05-27  9:30 UTC (permalink / raw)
  To: linux-usb; +Cc: Greg KH, linux-kernel

Raise the maximum number of usb-serial devices to 256, which is the
actual limit supported by the codebase.

Signed-off-by: Jakob-Tobias Winter <tobias@linuxdingsda.de>
Tested-by: Jakob-Tobias Winter <tobias@linuxdingsda.de>

---
 include/linux/usb/serial.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index 302ddf5..c0ce5ed 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -20,7 +20,7 @@
 #include <linux/kfifo.h>

 #define SERIAL_TTY_MAJOR       188     /* Nice legal number now */
-#define SERIAL_TTY_MINORS      254     /* loads of devices :) */
+#define SERIAL_TTY_MINORS      256     /* loads of devices :) */
 #define SERIAL_TTY_NO_MINOR    255     /* No minor was assigned */

 /* The maximum number of ports one device can grab at once */
-- 
1.7.10.4


^ permalink raw reply related	[flat|nested] 13+ messages in thread

* Re: [PATCH] Raise the maximum number of usb-serial devices to 256
  2013-05-27  9:30   ` [PATCH] Raise the maximum number of usb-serial devices to 256 Tobias Winter
@ 2013-05-28  6:17     ` Rob Landley
       [not found]     ` <87obbwbo8s.fsf@nemi.mork.no>
  1 sibling, 0 replies; 13+ messages in thread
From: Rob Landley @ 2013-05-28  6:17 UTC (permalink / raw)
  To: Tobias Winter; +Cc: linux-usb, Greg KH, linux-kernel

On 05/27/2013 04:30:12 AM, Tobias Winter wrote:
> Raise the maximum number of usb-serial devices to 256, which is the
> actual limit supported by the codebase.
> 
> Signed-off-by: Jakob-Tobias Winter <tobias@linuxdingsda.de>
> Tested-by: Jakob-Tobias Winter <tobias@linuxdingsda.de>
> 
> ---
>  include/linux/usb/serial.h |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
> index 302ddf5..c0ce5ed 100644
> --- a/include/linux/usb/serial.h
> +++ b/include/linux/usb/serial.h
> @@ -20,7 +20,7 @@
>  #include <linux/kfifo.h>
> 
>  #define SERIAL_TTY_MAJOR       188     /* Nice legal number now */
> -#define SERIAL_TTY_MINORS      254     /* loads of devices :) */
> +#define SERIAL_TTY_MINORS      256     /* loads of devices :) */
>  #define SERIAL_TTY_NO_MINOR    255     /* No minor was assigned */

So SERIAL_TTY_NO_MINOR is now a valid minor?

Rob

^ permalink raw reply	[flat|nested] 13+ messages in thread

[parent not found: <87obbwbo8s.fsf@nemi.mork.no>]

[parent not found: <51A332E2.1090403@linuxdingsda.de>]

* Re: [RFC] raise the maximum number of usb-serial devices to 512
       [not found]       ` <51A332E2.1090403@linuxdingsda.de>
@ 2013-06-04  2:49         ` Greg KH
  2013-06-04  2:59           ` Dave Jones
                             ` (3 more replies)
  0 siblings, 4 replies; 13+ messages in thread
From: Greg KH @ 2013-06-04  2:49 UTC (permalink / raw)
  To: Tobias Winter, Bjørn Mork, Rob Landley; +Cc: linux-usb, linux-kernel

On Mon, May 27, 2013 at 02:28:51PM +0200, Bjørn Mork wrote:
> But, IMHO, a nicer approach would be to make the allocation completely
> dynamic, using e.g. the idr subsystem. Static tables are always feel
> like straight jackets to me, no matter how big they are :)

You are right, I didn't change the code to use idr (it predates idr by
about a decade or so), because I thought we needed the "rage" logic that
the usb-serial minor reservation does.

But I'm not so sure anymore, so here's a patch to change to use the idr
code, and should remove all minor number limitations (well 65k is the
limit the tty core should be setting I think.)

Tobias, can you test this patch out?  Note, I only compiled it, did not
get the chance to actually run it, so it might not work at all.

thanks,

greg k-h

Subject: [PATCH] usb: serial: remove minor number limitation of 255


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

 drivers/usb/serial/usb-serial.c |   86 +++++++++++++++++-----------------------
 1 file changed, 38 insertions(+), 48 deletions(-)

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 4753c00..74b6f08 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -37,6 +37,7 @@
 #include <linux/usb.h>
 #include <linux/usb/serial.h>
 #include <linux/kfifo.h>
+#include <linux/idr.h>
 #include "pl2303.h"
 
 #define DRIVER_AUTHOR "Greg Kroah-Hartman <gregkh@linuxfoundation.org>"
@@ -49,7 +50,7 @@
    drivers depend on it.
 */
 
-static struct usb_serial *serial_table[SERIAL_TTY_MINORS];
+static DEFINE_IDR(serial_minors);
 static DEFINE_MUTEX(table_lock);
 static LIST_HEAD(usb_serial_driver_list);
 
@@ -61,59 +62,52 @@ static LIST_HEAD(usb_serial_driver_list);
 struct usb_serial *usb_serial_get_by_index(unsigned index)
 {
 	struct usb_serial *serial;
+	struct usb_serial_port *port;
 
 	mutex_lock(&table_lock);
-	serial = serial_table[index];
-
-	if (serial) {
-		mutex_lock(&serial->disc_mutex);
-		if (serial->disconnected) {
-			mutex_unlock(&serial->disc_mutex);
-			serial = NULL;
-		} else {
-			kref_get(&serial->kref);
-		}
-	}
+	port = idr_find(&serial_minors, index);
 	mutex_unlock(&table_lock);
+	if (!port)
+		return NULL;
+
+	serial = port->serial;
+	kref_get(&serial->kref);
 	return serial;
 }
 
-static struct usb_serial *get_free_serial(struct usb_serial *serial,
-					int num_ports, unsigned int *minor)
+static int get_free_port(struct usb_serial_port *port)
 {
-	unsigned int i, j;
-	int good_spot;
-
-	dev_dbg(&serial->interface->dev, "%s %d\n", __func__, num_ports);
+	int i;
 
-	*minor = 0;
 	mutex_lock(&table_lock);
-	for (i = 0; i < SERIAL_TTY_MINORS; ++i) {
-		if (serial_table[i])
-			continue;
+	i = idr_alloc(&serial_minors, port, 0, 0, GFP_KERNEL);
+	if (i < 0)
+		return -EEXIST;
+	port->number = i;
+	mutex_unlock(&table_lock);
+	return i;
+}
 
-		good_spot = 1;
-		for (j = 1; j <= num_ports-1; ++j)
-			if ((i+j >= SERIAL_TTY_MINORS) || (serial_table[i+j])) {
-				good_spot = 0;
-				i += j;
-				break;
-			}
-		if (good_spot == 0)
-			continue;
+static int get_free_serial(struct usb_serial *serial, int num_ports,
+			   unsigned int *minor)
+{
+	unsigned int i;
+	unsigned int x;
 
-		*minor = i;
-		j = 0;
-		dev_dbg(&serial->interface->dev, "%s - minor base = %d\n", __func__, *minor);
-		for (i = *minor; (i < (*minor + num_ports)) && (i < SERIAL_TTY_MINORS); ++i) {
-			serial_table[i] = serial;
-			serial->port[j++]->number = i;
-		}
-		mutex_unlock(&table_lock);
-		return serial;
+	dev_dbg(&serial->interface->dev, "%s %d\n", __func__, num_ports);
+
+	*minor = 0xffffffff;
+	for (i = 0; i < num_ports; ++i) {
+		x = get_free_port(serial->port[i]);
+		if (x < 0)
+			goto error;
+		if (*minor == 0xffffffff)
+			*minor = x;
 	}
-	mutex_unlock(&table_lock);
-	return NULL;
+	return 0;
+error:
+	// FIXME unwind the already allocated minors
+	return -ENODEV;
 }
 
 static void return_serial(struct usb_serial *serial)
@@ -122,7 +116,7 @@ static void return_serial(struct usb_serial *serial)
 
 	mutex_lock(&table_lock);
 	for (i = 0; i < serial->num_ports; ++i)
-		serial_table[serial->minor + i] = NULL;
+		idr_remove(&serial_minors, serial->port[i]->number);
 	mutex_unlock(&table_lock);
 }
 
@@ -1041,7 +1035,7 @@ static int usb_serial_probe(struct usb_interface *interface,
 	 */
 	serial->disconnected = 1;
 
-	if (get_free_serial(serial, num_ports, &minor) == NULL) {
+	if (get_free_serial(serial, num_ports, &minor)) {
 		dev_err(ddev, "No more free serial devices\n");
 		goto probe_error;
 	}
@@ -1225,7 +1219,6 @@ static struct usb_driver usb_serial_driver = {
 
 static int __init usb_serial_init(void)
 {
-	int i;
 	int result;
 
 	usb_serial_tty_driver = alloc_tty_driver(SERIAL_TTY_MINORS);
@@ -1233,9 +1226,6 @@ static int __init usb_serial_init(void)
 		return -ENOMEM;
 
 	/* Initialize our global data */
-	for (i = 0; i < SERIAL_TTY_MINORS; ++i)
-		serial_table[i] = NULL;
-
 	result = bus_register(&usb_serial_bus_type);
 	if (result) {
 		pr_err("%s - registering bus driver failed\n", __func__);

^ permalink raw reply related	[flat|nested] 13+ messages in thread

* Re: [RFC] raise the maximum number of usb-serial devices to 512
  2013-06-04  2:49         ` [RFC] raise the maximum number of usb-serial devices to 512 Greg KH
@ 2013-06-04  2:59           ` Dave Jones
  2013-06-04 16:12             ` Greg KH
  2013-06-04 11:04           ` Johan Hovold
                             ` (2 subsequent siblings)
  3 siblings, 1 reply; 13+ messages in thread
From: Dave Jones @ 2013-06-04  2:59 UTC (permalink / raw)
  To: Greg KH
  Cc: Tobias Winter, Bjørn Mork, Rob Landley, linux-usb,
	linux-kernel

On Mon, Jun 03, 2013 at 07:49:59PM -0700, Greg Kroah-Hartman wrote:
 > On Mon, May 27, 2013 at 02:28:51PM +0200, Bjørn Mork wrote:
 > > But, IMHO, a nicer approach would be to make the allocation completely
 > > dynamic, using e.g. the idr subsystem. Static tables are always feel
 > > like straight jackets to me, no matter how big they are :)
 > 
 > You are right, I didn't change the code to use idr (it predates idr by
 > about a decade or so), because I thought we needed the "rage" logic that
 > the usb-serial minor reservation does.

Rage logic sounds like my kinda code.


 > +static int get_free_port(struct usb_serial_port *port)
 >  {
 > -	unsigned int i, j;
 > -	int good_spot;
 > -
 > -	dev_dbg(&serial->interface->dev, "%s %d\n", __func__, num_ports);
 > +	int i;
 >  
 > -	*minor = 0;
 >  	mutex_lock(&table_lock);
 > -	for (i = 0; i < SERIAL_TTY_MINORS; ++i) {
 > -		if (serial_table[i])
 > -			continue;
 > +	i = idr_alloc(&serial_minors, port, 0, 0, GFP_KERNEL);
 > +	if (i < 0)
 > +		return -EEXIST;
 > +	port->number = i;
 > +	mutex_unlock(&table_lock);
 > +	return i;
 > +}

-EEXIST case misses the mutex unlock.

	Dave


^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [RFC] raise the maximum number of usb-serial devices to 512
  2013-06-04  2:59           ` Dave Jones
@ 2013-06-04 16:12             ` Greg KH
  0 siblings, 0 replies; 13+ messages in thread
From: Greg KH @ 2013-06-04 16:12 UTC (permalink / raw)
  To: Dave Jones, Tobias Winter, Bjørn Mork, Rob Landley,
	linux-usb, linux-kernel

On Mon, Jun 03, 2013 at 10:59:08PM -0400, Dave Jones wrote:
> On Mon, Jun 03, 2013 at 07:49:59PM -0700, Greg Kroah-Hartman wrote:
>  > On Mon, May 27, 2013 at 02:28:51PM +0200, Bjørn Mork wrote:
>  > > But, IMHO, a nicer approach would be to make the allocation completely
>  > > dynamic, using e.g. the idr subsystem. Static tables are always feel
>  > > like straight jackets to me, no matter how big they are :)
>  > 
>  > You are right, I didn't change the code to use idr (it predates idr by
>  > about a decade or so), because I thought we needed the "rage" logic that
>  > the usb-serial minor reservation does.
> 
> Rage logic sounds like my kinda code.

Late nite typo :)

>  > +static int get_free_port(struct usb_serial_port *port)
>  >  {
>  > -	unsigned int i, j;
>  > -	int good_spot;
>  > -
>  > -	dev_dbg(&serial->interface->dev, "%s %d\n", __func__, num_ports);
>  > +	int i;
>  >  
>  > -	*minor = 0;
>  >  	mutex_lock(&table_lock);
>  > -	for (i = 0; i < SERIAL_TTY_MINORS; ++i) {
>  > -		if (serial_table[i])
>  > -			continue;
>  > +	i = idr_alloc(&serial_minors, port, 0, 0, GFP_KERNEL);
>  > +	if (i < 0)
>  > +		return -EEXIST;
>  > +	port->number = i;
>  > +	mutex_unlock(&table_lock);
>  > +	return i;
>  > +}
> 
> -EEXIST case misses the mutex unlock.

Thanks, now fixed.

greg k-h

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [RFC] raise the maximum number of usb-serial devices to 512
  2013-06-04  2:49         ` [RFC] raise the maximum number of usb-serial devices to 512 Greg KH
  2013-06-04  2:59           ` Dave Jones
@ 2013-06-04 11:04           ` Johan Hovold
  2013-06-04 16:31             ` Greg KH
  2013-06-04 14:13           ` Alan Stern
  2013-06-04 17:27           ` Tobias Winter
  3 siblings, 1 reply; 13+ messages in thread
From: Johan Hovold @ 2013-06-04 11:04 UTC (permalink / raw)
  To: Greg KH
  Cc: Tobias Winter, Bjørn Mork, Rob Landley, linux-usb,
	linux-kernel

On Mon, Jun 03, 2013 at 07:49:59PM -0700, Greg KH wrote:
> On Mon, May 27, 2013 at 02:28:51PM +0200, Bjørn Mork wrote:
> > But, IMHO, a nicer approach would be to make the allocation completely
> > dynamic, using e.g. the idr subsystem. Static tables are always feel
> > like straight jackets to me, no matter how big they are :)
> 
> You are right, I didn't change the code to use idr (it predates idr by
> about a decade or so), because I thought we needed the "rage" logic that
> the usb-serial minor reservation does.
> 
> But I'm not so sure anymore, so here's a patch to change to use the idr
> code, and should remove all minor number limitations (well 65k is the
> limit the tty core should be setting I think.)
> 
> Tobias, can you test this patch out?  Note, I only compiled it, did not
> get the chance to actually run it, so it might not work at all.

I'm afraid this won't work in it's current form. Several drivers and
parts of usb-serial core still depend on the minor numbers being
consecutive for multi-port devices. There are also still references to
SERIAL_TTY_NO_MINOR (255) as well as SERIAL_TTY_MINORS that need to be
addressed.

> 
> thanks,
> 
> greg k-h
> 
> Subject: [PATCH] usb: serial: remove minor number limitation of 255
> 
> 
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
>  drivers/usb/serial/usb-serial.c |   86 +++++++++++++++++-----------------------
>  1 file changed, 38 insertions(+), 48 deletions(-)
> 
> diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
> index 4753c00..74b6f08 100644
> --- a/drivers/usb/serial/usb-serial.c
> +++ b/drivers/usb/serial/usb-serial.c
> @@ -37,6 +37,7 @@
>  #include <linux/usb.h>
>  #include <linux/usb/serial.h>
>  #include <linux/kfifo.h>
> +#include <linux/idr.h>
>  #include "pl2303.h"
>  
>  #define DRIVER_AUTHOR "Greg Kroah-Hartman <gregkh@linuxfoundation.org>"
> @@ -49,7 +50,7 @@
>     drivers depend on it.
>  */
>  
> -static struct usb_serial *serial_table[SERIAL_TTY_MINORS];
> +static DEFINE_IDR(serial_minors);
>  static DEFINE_MUTEX(table_lock);
>  static LIST_HEAD(usb_serial_driver_list);
>  
> @@ -61,59 +62,52 @@ static LIST_HEAD(usb_serial_driver_list);
>  struct usb_serial *usb_serial_get_by_index(unsigned index)
>  {
>  	struct usb_serial *serial;
> +	struct usb_serial_port *port;
>  
>  	mutex_lock(&table_lock);
> -	serial = serial_table[index];
> -
> -	if (serial) {
> -		mutex_lock(&serial->disc_mutex);
> -		if (serial->disconnected) {
> -			mutex_unlock(&serial->disc_mutex);
> -			serial = NULL;
> -		} else {
> -			kref_get(&serial->kref);
> -		}
> -	}
> +	port = idr_find(&serial_minors, index);
>  	mutex_unlock(&table_lock);
> +	if (!port)
> +		return NULL;
> +
> +	serial = port->serial;
> +	kref_get(&serial->kref);
>  	return serial;
>  }

We would still need to handle disconnect, and make sure to return with
the disc_mutex held unless disconnected.

>  
> -static struct usb_serial *get_free_serial(struct usb_serial *serial,
> -					int num_ports, unsigned int *minor)
> +static int get_free_port(struct usb_serial_port *port)
>  {
> -	unsigned int i, j;
> -	int good_spot;
> -
> -	dev_dbg(&serial->interface->dev, "%s %d\n", __func__, num_ports);
> +	int i;
>  
> -	*minor = 0;
>  	mutex_lock(&table_lock);
> -	for (i = 0; i < SERIAL_TTY_MINORS; ++i) {
> -		if (serial_table[i])
> -			continue;
> +	i = idr_alloc(&serial_minors, port, 0, 0, GFP_KERNEL);
> +	if (i < 0)

Missing mutex unlock (as already Dave noted).

> +		return -EEXIST;
> +	port->number = i;
> +	mutex_unlock(&table_lock);
> +	return i;
> +}
>  
> -		good_spot = 1;
> -		for (j = 1; j <= num_ports-1; ++j)
> -			if ((i+j >= SERIAL_TTY_MINORS) || (serial_table[i+j])) {
> -				good_spot = 0;
> -				i += j;
> -				break;
> -			}
> -		if (good_spot == 0)
> -			continue;
> +static int get_free_serial(struct usb_serial *serial, int num_ports,
> +			   unsigned int *minor)
> +{
> +	unsigned int i;
> +	unsigned int x;
>  
> -		*minor = i;
> -		j = 0;
> -		dev_dbg(&serial->interface->dev, "%s - minor base = %d\n", __func__, *minor);
> -		for (i = *minor; (i < (*minor + num_ports)) && (i < SERIAL_TTY_MINORS); ++i) {
> -			serial_table[i] = serial;
> -			serial->port[j++]->number = i;
> -		}
> -		mutex_unlock(&table_lock);
> -		return serial;
> +	dev_dbg(&serial->interface->dev, "%s %d\n", __func__, num_ports);
> +
> +	*minor = 0xffffffff;
> +	for (i = 0; i < num_ports; ++i) {
> +		x = get_free_port(serial->port[i]);
> +		if (x < 0)
> +			goto error;
> +		if (*minor == 0xffffffff)
> +			*minor = x;
>  	}
> -	mutex_unlock(&table_lock);
> -	return NULL;
> +	return 0;
> +error:
> +	// FIXME unwind the already allocated minors
> +	return -ENODEV;
>  }

As mentioned above, usb-serial core and several drivers currently depend
on us returning the first minor in a consecutive range. It's mostly used
to determine the per device port index, so storing that index in the port
structure could possibly be sufficient.

>  
>  static void return_serial(struct usb_serial *serial)
> @@ -122,7 +116,7 @@ static void return_serial(struct usb_serial *serial)
>  
>  	mutex_lock(&table_lock);
>  	for (i = 0; i < serial->num_ports; ++i)
> -		serial_table[serial->minor + i] = NULL;
> +		idr_remove(&serial_minors, serial->port[i]->number);
>  	mutex_unlock(&table_lock);
>  }
>  
> @@ -1041,7 +1035,7 @@ static int usb_serial_probe(struct usb_interface *interface,
>  	 */
>  	serial->disconnected = 1;
>  
> -	if (get_free_serial(serial, num_ports, &minor) == NULL) {
> +	if (get_free_serial(serial, num_ports, &minor)) {
>  		dev_err(ddev, "No more free serial devices\n");
>  		goto probe_error;
>  	}
> @@ -1225,7 +1219,6 @@ static struct usb_driver usb_serial_driver = {
>  
>  static int __init usb_serial_init(void)
>  {
> -	int i;
>  	int result;
>  
>  	usb_serial_tty_driver = alloc_tty_driver(SERIAL_TTY_MINORS);
> @@ -1233,9 +1226,6 @@ static int __init usb_serial_init(void)
>  		return -ENOMEM;
>  
>  	/* Initialize our global data */

You could remove the above comment as well.

> -	for (i = 0; i < SERIAL_TTY_MINORS; ++i)
> -		serial_table[i] = NULL;
> -
>  	result = bus_register(&usb_serial_bus_type);
>  	if (result) {
>  		pr_err("%s - registering bus driver failed\n", __func__);

Thanks,
Johan

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [RFC] raise the maximum number of usb-serial devices to 512
  2013-06-04 11:04           ` Johan Hovold
@ 2013-06-04 16:31             ` Greg KH
  0 siblings, 0 replies; 13+ messages in thread
From: Greg KH @ 2013-06-04 16:31 UTC (permalink / raw)
  To: Johan Hovold
  Cc: Tobias Winter, Bjørn Mork, Rob Landley, linux-usb,
	linux-kernel

On Tue, Jun 04, 2013 at 01:04:01PM +0200, Johan Hovold wrote:
> On Mon, Jun 03, 2013 at 07:49:59PM -0700, Greg KH wrote:
> > On Mon, May 27, 2013 at 02:28:51PM +0200, Bjørn Mork wrote:
> > > But, IMHO, a nicer approach would be to make the allocation completely
> > > dynamic, using e.g. the idr subsystem. Static tables are always feel
> > > like straight jackets to me, no matter how big they are :)
> > 
> > You are right, I didn't change the code to use idr (it predates idr by
> > about a decade or so), because I thought we needed the "rage" logic that
> > the usb-serial minor reservation does.
> > 
> > But I'm not so sure anymore, so here's a patch to change to use the idr
> > code, and should remove all minor number limitations (well 65k is the
> > limit the tty core should be setting I think.)
> > 
> > Tobias, can you test this patch out?  Note, I only compiled it, did not
> > get the chance to actually run it, so it might not work at all.
> 
> I'm afraid this won't work in it's current form. Several drivers and
> parts of usb-serial core still depend on the minor numbers being
> consecutive for multi-port devices.

You are right, let me go fix up the "port->number" assumption first,
which will let this become easier.  That should have been fixed a long
time ago.

> There are also still references to SERIAL_TTY_NO_MINOR (255) as well
> as SERIAL_TTY_MINORS that need to be addressed.

Yeah, I knew it was too good to be true that a simple 45 line patch
would solve this properly :)

> > +	port = idr_find(&serial_minors, index);
> >  	mutex_unlock(&table_lock);
> > +	if (!port)
> > +		return NULL;
> > +
> > +	serial = port->serial;
> > +	kref_get(&serial->kref);
> >  	return serial;
> >  }
> 
> We would still need to handle disconnect, and make sure to return with
> the disc_mutex held unless disconnected.

Alan noticed this as well, I've now fixed that, thanks.

> > +	dev_dbg(&serial->interface->dev, "%s %d\n", __func__, num_ports);
> > +
> > +	*minor = 0xffffffff;
> > +	for (i = 0; i < num_ports; ++i) {
> > +		x = get_free_port(serial->port[i]);
> > +		if (x < 0)
> > +			goto error;
> > +		if (*minor == 0xffffffff)
> > +			*minor = x;
> >  	}
> > -	mutex_unlock(&table_lock);
> > -	return NULL;
> > +	return 0;
> > +error:
> > +	// FIXME unwind the already allocated minors
> > +	return -ENODEV;
> >  }
> 
> As mentioned above, usb-serial core and several drivers currently depend
> on us returning the first minor in a consecutive range. It's mostly used
> to determine the per device port index, so storing that index in the port
> structure could possibly be sufficient.

Yes, I'll go fix that up first, before making these changes, as it's
independant.

> > @@ -1233,9 +1226,6 @@ static int __init usb_serial_init(void)
> >  		return -ENOMEM;
> >  
> >  	/* Initialize our global data */
> 
> You could remove the above comment as well.
> 
> > -	for (i = 0; i < SERIAL_TTY_MINORS; ++i)
> > -		serial_table[i] = NULL;
> > -
> >  	result = bus_register(&usb_serial_bus_type);

I thought about it, but we also register the bus variables, and some
other things here as well, so I left it in.

thanks for the review.

greg k-h

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [RFC] raise the maximum number of usb-serial devices to 512
  2013-06-04  2:49         ` [RFC] raise the maximum number of usb-serial devices to 512 Greg KH
  2013-06-04  2:59           ` Dave Jones
  2013-06-04 11:04           ` Johan Hovold
@ 2013-06-04 14:13           ` Alan Stern
  2013-06-04 16:17             ` Greg KH
  2013-06-04 17:27           ` Tobias Winter
  3 siblings, 1 reply; 13+ messages in thread
From: Alan Stern @ 2013-06-04 14:13 UTC (permalink / raw)
  To: Greg KH
  Cc: Tobias Winter, Bjørn Mork, Rob Landley, linux-usb,
	linux-kernel

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: TEXT/PLAIN; charset=UTF-8, Size: 1945 bytes --]

On Mon, 3 Jun 2013, Greg KH wrote:

> On Mon, May 27, 2013 at 02:28:51PM +0200, Bjørn Mork wrote:
> > But, IMHO, a nicer approach would be to make the allocation completely
> > dynamic, using e.g. the idr subsystem. Static tables are always feel
> > like straight jackets to me, no matter how big they are :)
> 
> You are right, I didn't change the code to use idr (it predates idr by
> about a decade or so), because I thought we needed the "rage" logic that
> the usb-serial minor reservation does.
> 
> But I'm not so sure anymore, so here's a patch to change to use the idr
> code, and should remove all minor number limitations (well 65k is the
> limit the tty core should be setting I think.)
> 
> Tobias, can you test this patch out?  Note, I only compiled it, did not
> get the chance to actually run it, so it might not work at all.
> 
> thanks,
> 
> greg k-h


> @@ -61,59 +62,52 @@ static LIST_HEAD(usb_serial_driver_list);
>  struct usb_serial *usb_serial_get_by_index(unsigned index)
>  {
>  	struct usb_serial *serial;
> +	struct usb_serial_port *port;
>  
>  	mutex_lock(&table_lock);
> -	serial = serial_table[index];
> -
> -	if (serial) {
> -		mutex_lock(&serial->disc_mutex);
> -		if (serial->disconnected) {
> -			mutex_unlock(&serial->disc_mutex);
> -			serial = NULL;
> -		} else {
> -			kref_get(&serial->kref);
> -		}
> -	}
> +	port = idr_find(&serial_minors, index);
>  	mutex_unlock(&table_lock);
> +	if (!port)
> +		return NULL;
> +
> +	serial = port->serial;
> +	kref_get(&serial->kref);
>  	return serial;
>  }

The test for serial->disconnected got lost.  And the locking isn't 
right; the routine is documented to return with serial->disc_mutex held 
(in the case where the device hasn't been disconnected).

Also, the kref_get() needs to occur within the scope of the table_lock.

I didn't check the rest of the patch for similar errors.  Finding three 
in the first function seemed like enough.  :-)

Alan Stern


^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [RFC] raise the maximum number of usb-serial devices to 512
  2013-06-04 14:13           ` Alan Stern
@ 2013-06-04 16:17             ` Greg KH
  0 siblings, 0 replies; 13+ messages in thread
From: Greg KH @ 2013-06-04 16:17 UTC (permalink / raw)
  To: Alan Stern
  Cc: Tobias Winter, Bjørn Mork, Rob Landley, linux-usb,
	linux-kernel

On Tue, Jun 04, 2013 at 10:13:47AM -0400, Alan Stern wrote:
> On Mon, 3 Jun 2013, Greg KH wrote:
> 
> > On Mon, May 27, 2013 at 02:28:51PM +0200, Bj?rn Mork wrote:
> > > But, IMHO, a nicer approach would be to make the allocation completely
> > > dynamic, using e.g. the idr subsystem. Static tables are always feel
> > > like straight jackets to me, no matter how big they are :)
> > 
> > You are right, I didn't change the code to use idr (it predates idr by
> > about a decade or so), because I thought we needed the "rage" logic that
> > the usb-serial minor reservation does.
> > 
> > But I'm not so sure anymore, so here's a patch to change to use the idr
> > code, and should remove all minor number limitations (well 65k is the
> > limit the tty core should be setting I think.)
> > 
> > Tobias, can you test this patch out?  Note, I only compiled it, did not
> > get the chance to actually run it, so it might not work at all.
> > 
> > thanks,
> > 
> > greg k-h
> 
> 
> > @@ -61,59 +62,52 @@ static LIST_HEAD(usb_serial_driver_list);
> >  struct usb_serial *usb_serial_get_by_index(unsigned index)
> >  {
> >  	struct usb_serial *serial;
> > +	struct usb_serial_port *port;
> >  
> >  	mutex_lock(&table_lock);
> > -	serial = serial_table[index];
> > -
> > -	if (serial) {
> > -		mutex_lock(&serial->disc_mutex);
> > -		if (serial->disconnected) {
> > -			mutex_unlock(&serial->disc_mutex);
> > -			serial = NULL;
> > -		} else {
> > -			kref_get(&serial->kref);
> > -		}
> > -	}
> > +	port = idr_find(&serial_minors, index);
> >  	mutex_unlock(&table_lock);
> > +	if (!port)
> > +		return NULL;
> > +
> > +	serial = port->serial;
> > +	kref_get(&serial->kref);
> >  	return serial;
> >  }
> 
> The test for serial->disconnected got lost.  And the locking isn't 
> right; the routine is documented to return with serial->disc_mutex held 
> (in the case where the device hasn't been disconnected).
> 
> Also, the kref_get() needs to occur within the scope of the table_lock.

Thanks, for some reason I ignored this when converting the code, that's
what I get for not even testing...

> I didn't check the rest of the patch for similar errors.  Finding three 
> in the first function seemed like enough.  :-)

Fair enough, I've now fixed this up, and will see if it runs properly.

thanks,

greg k-h

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [RFC] raise the maximum number of usb-serial devices to 512
  2013-06-04  2:49         ` [RFC] raise the maximum number of usb-serial devices to 512 Greg KH
                             ` (2 preceding siblings ...)
  2013-06-04 14:13           ` Alan Stern
@ 2013-06-04 17:27           ` Tobias Winter
  2013-06-04 17:53             ` Greg KH
  3 siblings, 1 reply; 13+ messages in thread
From: Tobias Winter @ 2013-06-04 17:27 UTC (permalink / raw)
  To: Greg KH; +Cc: Bjørn Mork, Rob Landley, linux-usb, linux-kernel

On 04.06.2013 04:49, Greg KH wrote:
> Tobias, can you test this patch out?  Note, I only compiled it, did not
> get the chance to actually run it, so it might not work at all.

Sure, I'll gladly give it a try. Seeing the comments on the code, I'm
just wondering if there might be a more recent version to run?

> But I'm not so sure anymore, so here's a patch to change to use the
> idr code, and should remove all minor number limitations (well 65k is
> the limit the tty core should be setting I think.)

That's a tough one to break :)

Tobias

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [RFC] raise the maximum number of usb-serial devices to 512
  2013-06-04 17:27           ` Tobias Winter
@ 2013-06-04 17:53             ` Greg KH
  0 siblings, 0 replies; 13+ messages in thread
From: Greg KH @ 2013-06-04 17:53 UTC (permalink / raw)
  To: Tobias Winter; +Cc: Bjørn Mork, Rob Landley, linux-usb, linux-kernel

On Tue, Jun 04, 2013 at 07:27:20PM +0200, Tobias Winter wrote:
> On 04.06.2013 04:49, Greg KH wrote:
> > Tobias, can you test this patch out?  Note, I only compiled it, did not
> > get the chance to actually run it, so it might not work at all.
> 
> Sure, I'll gladly give it a try. Seeing the comments on the code, I'm
> just wondering if there might be a more recent version to run?

Give me a day, it's going to take some more reworks to get this all to
work properly, I'll send a new patch series then.

thanks,

greg k-h

^ permalink raw reply	[flat|nested] 13+ messages in thread

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Thread overview: 13+ messages (download: mbox.gz follow: Atom feed
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2013-05-24 13:56 linux-3.9.3 - hit limit of 255 usb->serial devices Tobias Winter
2013-05-24 17:23 ` Greg KH
2013-05-27  9:30   ` [PATCH] Raise the maximum number of usb-serial devices to 256 Tobias Winter
2013-05-28  6:17     ` Rob Landley
     [not found]     ` <87obbwbo8s.fsf@nemi.mork.no>
     [not found]       ` <51A332E2.1090403@linuxdingsda.de>
2013-06-04  2:49         ` [RFC] raise the maximum number of usb-serial devices to 512 Greg KH
2013-06-04  2:59           ` Dave Jones
2013-06-04 16:12             ` Greg KH
2013-06-04 11:04           ` Johan Hovold
2013-06-04 16:31             ` Greg KH
2013-06-04 14:13           ` Alan Stern
2013-06-04 16:17             ` Greg KH
2013-06-04 17:27           ` Tobias Winter
2013-06-04 17:53             ` Greg KH

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