new locking in change_termios breaks USB serial drivers

[Al Borchers]

2.6.9-rc3 changes the locking in the tty_ioctl.c function
change_termios().  It gets a spin_lock_irqsave(&tty_termios_lock,...)
before calling the tty driver's set_termios function.

This means that the drivers' set_termios functions cannot sleep.

Unfortunately, many USB serial drivers' set_termios functions
send an urb to change the termios settings and sleep waiting for
it to complete.

I just looked quickly, but it seems belkin_sa.c, digi_acceleport.c,
ftdi_sio.c, io_ti.c, kl5usb105.c, mct_u232.c, pl2303.c, and whiteheat.c
all sleep in their set_termios functions.

If this locking in change_termios() stays, we are going to have to
fix set_termios in all of these drivers.  I am updating io_ti.c right
now.

-- Al

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