Bug 49061 - serial port with -clocal hangs machine
serial port with -clocal hangs machine
Product: Red Hat Linux
Classification: Retired
Component: kernel (Show other bugs)
i386 Linux
medium Severity medium
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Assigned To: Arjan van de Ven
Brock Organ
Depends On:
  Show dependency treegraph
Reported: 2001-07-13 07:42 EDT by paulh
Modified: 2007-04-18 12:34 EDT (History)
1 user (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Last Closed: 2003-06-06 10:40:18 EDT
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RHEL 7.3 requirements from Atomic Host:
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Description paulh 2001-07-13 07:42:03 EDT
From Bugzilla Helper:
User-Agent: Mozilla/4.76 [en] (X11; U; Linux 2.4.2-ieee1394 i686)

Description of problem:
Setting clocal off on a serial port makes the port inaccessible and
eventually panics
the kernel

How reproducible:

Steps to Reproduce:
1.stty -a </dev/ttyS0
2.stty -clocal </dev/ttyS0
3.stty -a </dev/ttyS0

Actual Results:  The second stty -a produced no output. User software which
repeatedly tried to
open() this port eventually caused kernel panic

Expected Results:  Second stty-a gives same results as second one except
-clocal is reported

Additional info:

This bug was noticed whilst debugging Ricardo Fachetti's libmodem library.
under development would crash prematurely leaving clocal off on the port.

There are 2 ways to free the port - reboot or run minicom and killall it
after it has opened the port.
Comment 1 Russell King 2001-11-29 08:15:35 EST
unsetting clocal makes the open block until the attached device asserts the DCD

Could you supply details of the panic, and a method that causes it please?

Comment 2 Alan Cox 2003-06-06 10:40:18 EDT
No reply in over a year, closing

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