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:

nptl/tst-cancel24.out
nptl/tst-cancelx4.out
nptl/tst-cancelx5.out
nptl/tst-cancelx16.out
nptl/tst-cancelx17.out
nptl/tst-cancelx18.out
nptl/tst-cancelx20.out
nptl/tst-cancelx21.out
nptl/tst-cleanupx0.out
nptl/tst-cleanupx1.out
nptl/tst-cleanupx3.out
nptl/tst-cleanupx4.out
nptl/tst-oncex3.out
nptl/tst-oncex4.out
rt/tst-mqueue8x.out


#include <unistd.h>
#include <pthread.h>
#include <stdio.h>

/* Cleanup handling test.  */
static int cl_called;

static void
cl (void *arg)
{
  printf("in cl\n");
  ++cl_called;
}

void *tf(void *arg)
{
  char c;

  printf("in tf\n");
  pthread_cleanup_push (cl, NULL);
  printf("waiting on stdin\n");
  read(0, &c, 1);
  pthread_cleanup_pop (0);
}

int main()
{
  pthread_t th;
  pthread_create(&th, NULL, tf, NULL);
  sleep(1);
  printf("cancelling\n");
  pthread_cancel(th);
  sleep(1);
  printf("%d\n", cl_called);
  return 0;
}