The appended program works fine if you build it with "gcc cancel.c -pthread". It creates a thread that blocks on stdin in a "pthread_cleanup_push()" context. The main thread then cancels it, at which point the created thread calls the cancel handler and returns. However, if you add "-fexceptions" (or, equivalently, build the program with g++ instead of gcc) the cancellation handler doesn't get called. This works fine on x86.
It's not clear if this is gcc or glibc bug, but I'm filing it as a glibc bug for now, since there don't seem to be any similar failures in the gcc testsuite.
This failure mode breaks the following glibc tests:
/* Cleanup handling test. */
static int cl_called;
cl (void *arg)
void *tf(void *arg)
pthread_cleanup_push (cl, NULL);
printf("waiting on stdin\n");
read(0, &c, 1);
pthread_create(&th, NULL, tf, NULL);