thread-safety of rtems_cpu_usage_report

Joel Sherrill joel.sherrill at
Fri Feb 13 19:50:10 UTC 2009

Till Straumann wrote:
> I look at rtems_cpu_usage_report() and it
> seems to me that the code merrily scans
> the _Objects_Information_table and accesses
> the Thread_Control blocks it finds there
> w/o using any kind of protection.
> What happens, e.g., if the _Objects_Information_table
> gets extended or otherwise modified by another
> thread while the code is scanning the table?
> Am I missing something?
no. :(

I had always wanted to change it to a loop
from min to max id around a "get cpu use"
task id based information call. Then it
can fail on each one.

But anything using iterate over all tasks is
not thread safe. Perhaps it would be best
to put that call in an allocation critical section.
Then the set cannot change since there are
no create/delete's allowed.
> -- Till
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Joel Sherrill, Ph.D.             Director of Research & Development
joel.sherrill at        On-Line Applications Research
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