I have noticed a problem within many of the Linux ACPI-related drivers.

When ACPI_FUNCTION_TRACE() is used, all return() statements within the 
function should use the ACPI return macros (return_ACPI_STATUS, etc.) instead 
of just a raw return. These return macros maintain the function nesting count 
(nesting count is incremented by ACPI_FUNCTION_TRACE, and decremented by the 
return macros.)

The nesting depth is very useful when analyzing execution traces of ACPI code.