The file sysdeps/unix/sysv/linux/tst-skeleton-affinity.c is used to implement the testing for sched_setaffinity and pthread_setaffiniyt_np, among various APIs.

In the "test_size" routine we have this code:

152   if (getaffinity (kernel_size, initial_set) < 0)
153     {
154       printf ("error: size %zu: getaffinity: %m\n", size);
155       return false;
156     }
157   if (setaffinity (kernel_size, initial_set) < 0)
158     {
159       printf ("error: size %zu: setaffinity: %m\n", size);
160       return true;
161     }

The point being that you should be able to get, and then set the affinity of the process (they should match) and this should be idempotent for the test.

But in the "setaffinity" case we "return true;" on error which skips the rest of the tests and silently doesn't report the error.

This looks like a typo, and it should be "return false;" for this case?