Hang on 2.2.17 - serial/tty related?

From: Russell King (rmk@arm.linux.org.uk)
Date: Wed Sep 20 2000 - 16:45:59 EST


Hi,

I just experianced a complete hang of one of my systems here after using
the serial port a lot (ie, open, read/write, close). I was using minicom,
and I started to notice that each time I quit minicom, it would not exit.

ps alx revealed that it was waiting in tty_wait_until_sent, yet the serial
port was not doing anything at all (I've got a couple of LEDs on the Tx
and Rx lines). However, the port was in xon/xoff mode, but it seemed to
be capable of transmitting immediately prior (note that at this time, the
remote end had no capability to send an xon character to stop the
transmission).

When I say "waiting" above, I mean waiting for over 1 minute, dispite the
timeouts being set at the default. Here are the port settings:

/dev/ttyS2, Line 2, UART: 16550A, Port: 0x80092900, IRQ: 34
        Baud_base: 460800, close_delay: 50, divisor: 0
        Flags: spd_normal

When the actual crash happened, I changed the baud rate on the target
system, and just changed the local baud rate to 115200. I then hit the
enter key and that was game over. No response on network, nor X. The
machine was completely and utterly dead to the point of requiring a
hardware reset.

The serial driver is based on Tytso's driver; the changes present
are to allow interrupt 0, high port numbers, and the baud_base to
be specified when ports are registered with it via register_serial().

There was no oops, sorry.
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