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A USB-serial converter device is plugged into a system, and a process
opens it's device node. If the device is physically removed whilst the
process still has its device node open, then other processes can
sucessfully open the now non-existent device's node. I would expect
that open() on a device that has been physically removed should return
ENODEV.
This is manifesting itself with getty on my system. I do the following:
1. set up inittab to spawn getty on ttyUSB0, eg:
T1:23:respawn:/sbin/getty -L ttyUSB0 115200 vt100
2. Plug in USB-serial converter cable
3. Wait for a login prompt on a terminal program attached to the serial
cable
4. Login
5. Pull the USB-serial converter cable from the box
6. getty doesn't realise that ttyUSB0 no longer exists as /dev/ttyUSB0
can still be opened.
7. Re-insert the USB-serial converter cable
8. You should no longer get a login prompt over the serial cable, as
the the USB-serial cable now shows up as /dev/ttyUSB1, and getty is
trying to talk to /dev/ttyUSB0.
The attached patch will cause open("/dev/ttyUSB0", O_RDONLY) to return
ENODEV after the USB-serial converter has been pulled. The patch was
created against 2.6.28.1. I can supply it against something else if
needs be. It is fairly simple, so should be OK.
I am using a pl2303 device, although I don't think that makes any
difference.
From: James Woodcock <James.Woodcock@ACULAB.COM>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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| .. | ||
| aircable.c | ||
| ark3116.c | ||
| belkin_sa.c | ||
| belkin_sa.h | ||
| bus.c | ||
| ch341.c | ||
| ChangeLog.history | ||
| console.c | ||
| cp2101.c | ||
| cyberjack.c | ||
| cypress_m8.c | ||
| cypress_m8.h | ||
| digi_acceleport.c | ||
| empeg.c | ||
| ezusb.c | ||
| ezusb_convert.pl | ||
| ftdi_sio.c | ||
| ftdi_sio.h | ||
| funsoft.c | ||
| garmin_gps.c | ||
| generic.c | ||
| hp4x.c | ||
| io_16654.h | ||
| io_edgeport.c | ||
| io_edgeport.h | ||
| io_ionsp.h | ||
| io_tables.h | ||
| io_ti.c | ||
| io_ti.h | ||
| io_usbvend.h | ||
| ipaq.c | ||
| ipaq.h | ||
| ipw.c | ||
| ir-usb.c | ||
| iuu_phoenix.c | ||
| iuu_phoenix.h | ||
| Kconfig | ||
| keyspan.c | ||
| keyspan.h | ||
| keyspan_pda.c | ||
| keyspan_usa26msg.h | ||
| keyspan_usa28msg.h | ||
| keyspan_usa49msg.h | ||
| keyspan_usa67msg.h | ||
| keyspan_usa90msg.h | ||
| kl5kusb105.c | ||
| kl5kusb105.h | ||
| kobil_sct.c | ||
| kobil_sct.h | ||
| Makefile | ||
| Makefile-keyspan_pda_fw | ||
| mct_u232.c | ||
| mct_u232.h | ||
| mos7720.c | ||
| mos7840.c | ||
| moto_modem.c | ||
| navman.c | ||
| omninet.c | ||
| opticon.c | ||
| option.c | ||
| oti6858.c | ||
| oti6858.h | ||
| pl2303.c | ||
| pl2303.h | ||
| safe_serial.c | ||
| siemens_mpi.c | ||
| sierra.c | ||
| spcp8x5.c | ||
| ti_usb_3410_5052.c | ||
| ti_usb_3410_5052.h | ||
| usb-serial.c | ||
| usb_debug.c | ||
| visor.c | ||
| visor.h | ||
| whiteheat.c | ||
| whiteheat.h | ||