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; }
Here's another example: https://github.com/cagney/pthread-cancel
Closing since tile is no longer a supported target.
Re-opening, bug also occurs on amd64
Thread cancellation on glibc requires gcc exception frame information provided by PT_GNU_EH_FRAME and the compiler must instruct the linker to produce it by --eh-frame-hdr. On you example you are linking the shared library using linker command directly, using default options. If you use either gcc driver (gcc -shared) or add --eh-frame-hdr on linker options the example does not fail.
Close based on comment #4.