ACPI and PRREMPT bug

[Nir Tzachar]

hello.

I'm encountering a problem with acpi on kernels where preempt is
enabled.
The problem is 100% reproducible on all kernels starting from 2.6.12.1
to 2.6.14
( i didn't try 2.6.11 and below ).

the problem is manifested via the battery proc interface. to produce it,
run in two terminals simultaneously: 
while true; do cat /proc/acpi/battery/BAT0/info; done

if i turn on kernel preemption (either voluntary or not), i get the
following error messages in dmesg:
Nov  7 08:31:00 lapnir ACPI-0292: *** Error: Looking up [SERN] in
namespace, AE_ALREADY_EXISTS
Nov  7 08:31:00 lapnir ACPI-0508: *** Error: Method execution failed
[\_SB_.PCI0.LPC_.EC__.GBIF] (Node c18f5d60), AE_ALREADY_EXISTS
Nov  7 08:31:02 lapnir ACPI-0213: *** Error: Method reached maximum
reentrancy limit (255)
Nov  7 08:31:02 lapnir ACPI-0508: *** Error: Method execution failed
[\_SB_.PCI0.LPC_.EC__.BAT0._BIF] (Node c18f5c20), AE_AML_METHOD_LIMIT

and with acpi debugging info turned on:
Nov  7 08:46:08 lapnir dswload-0292: *** Error: Looking up [SERN] in
namespace, AE_ALREADY_EXISTS
Nov  7 08:46:08 lapnir psloop-0287 [4399] ps_parse_loop         : During
name lookup/catalog, AE_ALREADY_EXISTS
Nov  7 08:46:08 lapnir psparse-0508: *** Error: Method execution failed
[\_SB_.PCI0.LPC_.EC__.GBIF] (Node c18f94e8), AE_ALREADY_EXISTS
Nov  7 08:46:08 lapnir osl-0856 [4403] os_wait_semaphore     : Failed to
acquire semaphore[c18de5e0|1|0], AE_TIME
Nov  7 08:46:08 lapnir dsmethod-0213: *** Error: Method reached maximum
reentrancy limit (255)
Nov  7 08:46:08 lapnir psparse-0508: *** Error: Method execution failed
[\_SB_.PCI0.LPC_.EC__.BAT0._BIF] (Node c18f9268), AE_AML_METHOD_LIMIT
Nov  7 08:46:08 lapnir acpi_battery-0144 [4449] battery_get_info      :
Error evaluating _BIF
Nov  7 08:46:08 lapnir dsmethod-0213: *** Error: Method reached maximum
reentrancy limit (255)
Nov  7 08:46:08 lapnir psparse-0508: *** Error: Method execution failed
[\_SB_.PCI0.LPC_.EC__.BAT0._BIF] (Node c18f9268), AE_AML_METHOD_LIMIT


this is repeated until a reboot. loading and unloading the battery
module does not help.

My computer is a thinkpad t43p, and i didn't try to reproduce it on
another laptop
(have no access to another model..).
If you need more info, let me know.

p.s. please cc me, im not in the list.

-- 
=========================================================
Nir Tzachar.

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