Hello all, this hang has been around for a long time, possibly more than 4 years, however probably due to timing changes I can hit this problem within minutes (vs days or weeks) on 2.6.35 (Ubuntu 10.10). So it's probably time to fix it. I'm mostly just poking around in the dark here as I've never looked at linux USB before. The hardware is hooked up as follows: IRTrans infrared receiver/display with an integrated FTDI usb-serial converter on board. To reproduce the hang the irserver daemon simply needs to be running while using the remote control (and producing data from the device). The daemon does a select() with a timeout of 10s on the USB device and then reads whatever bytes are present. In ftdi_sio.c this seems to cause ftdi_process_read_urb() to poll every 1 ms. Not what I expected but that's what is going on. The reads eventually stop returing data. Worse, when you try to exit the application, the close() syscall to the USB device hangs, apparently there is a use_count on the urb and it's waiting for a signal that will never come. This leaves a zombie process and a reboot is required to use the device again. Fortunately the new kernels have hang detection with comes in really handy: Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800137] irserver64 D 0000000000000000 0 2329 2143 0x00000004 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800147] ffff880056509b98 0000000000000046 ffff880000000000 0000000000015980 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800157] ffff880056509fd8 0000000000015980 ffff880056509fd8 ffff88005b755b80 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800165] 0000000000015980 0000000000015980 ffff880056509fd8 0000000000015980 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800174] Call Trace: Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800188] [<ffffffff814070fd>] usb_kill_urb+0x8d/0xd0 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800197] [<ffffffff8107f610>] ? autoremove_wake_function+0x0/0x40 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800207] [<ffffffff81036dd9>] ? default_spin_lock_flags+0x9/0x10 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800230] [<ffffffffa01352e1>] generic_cleanup+0x51/0xe0 [usbserial] Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800244] [<ffffffffa0135415>] usb_serial_generic_close+0x25/0x60 [usbserial] Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800255] [<ffffffffa0bf90fa>] ftdi_close+0x3a/0x80 [ftdi_sio] Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800266] [<ffffffffa013202c>] serial_down+0x2c/0x30 [usbserial] Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800274] [<ffffffff8135da62>] tty_port_shutdown+0x62/0x70 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800281] [<ffffffff8135e23d>] tty_port_close+0x2d/0x60 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800292] [<ffffffffa0132c42>] serial_close+0x42/0x80 [usbserial] Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800301] [<ffffffff81355cfb>] tty_release+0x17b/0x710 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800310] [<ffffffff81193509>] ? locks_remove_flock+0x109/0x150 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800319] [<ffffffff81193b8b>] ? vfs_lock_file+0x3b/0x40 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800328] [<ffffffff81193c21>] ? locks_remove_posix+0x91/0xc0 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800335] [<ffffffff815891be>] ? _raw_spin_lock+0xe/0x20 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800343] [<ffffffff81154245>] __fput+0xf5/0x210 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800350] [<ffffffff81154385>] fput+0x25/0x30 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800358] [<ffffffff811508cd>] filp_close+0x5d/0x90 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800367] [<ffffffff81062b4f>] put_files_struct+0x7f/0xf0 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800375] [<ffffffff81062c14>] exit_files+0x54/0x70 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800383] [<ffffffff81065177>] do_exit+0x167/0x3f0 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800391] [<ffffffff81065455>] do_group_exit+0x55/0xd0 Oct 24 19:20:58 frontendhd4 kernel: [ 1320.800400] [<ffffffff810654e7>] sys_exit_group+0x17/0x20 What should I look at next/what's the quickest way to track down this "lost" urb? Thanks, Debabrata -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
