Found problem in Thread class implementation

["Richard Rauch" <rrauch at itrgmbh dot de>]

Hi,

maybe I found a problem in schedulers code....

For debugging purposes I enabled some options:

- CYGVAR_KERNEL_THREADS_LIST
- CYGDBG_KERNEL_DEBUG_GDB_THREAD_SUPPORT

On application startup some threads should be created, but I am running in
an exception. The reason of exception is located here:

inline void
Cyg_Thread::add_to_list( void )
{
    // Add thread to housekeeping list
    Cyg_Scheduler::lock();

    if( thread_list == 0 )
        list_next = this;
    else {
        Cyg_Thread *prev = thread_list;
        do {
            if ( this == prev )
                break; // found it already!
            prev = prev->list_next;
        } while ( prev != thread_list );
        if ( this != prev ) {
            // insert it in the list:
            list_next = thread_list->list_next;
            thread_list->list_next = this;
        }
    }
    thread_list = this;

    Cyg_Scheduler::unlock();
}

In this loop prev becomes NULL, but there is no test on NULL, so the
statement <NULL>->list_next causes an exception!
Should there a test on NULL pointer only? I do not understand the reason for
while loop condition: while (prev != thread_list). Should I compare to NULL
here or is it more complex?


Thanks 

Richard

ITR GmbH
web:     http://www.itrgmbh.com
email:   info@itrgmbh.com


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