There is a race between __nptl_setxid and exiting detached thread, which
causes a deadlock on stack_cache_lock. The deadlock happens in this
state:
T1: setgroups -> __nptl_setxid (holding stack_cache_lock, waiting on cmdp->cntr == 0)
T2 (detached, exiting): start_thread -> __deallocate_stack (waiting on stack_cache_lock)
more threads waiting on stack_cache_lock in pthread_create
For non-detached threads, start_thread waits for its own setxid handler to
finish before exiting. Do this for detached threads as well.
advise_stack_range (pd->stackblock, pd->stackblock_size, (uintptr_t) pd,
pd->guardsize);
- /* If the thread is detached free the TCB. */
- if (IS_DETACHED (pd))
- /* Free the TCB. */
- __free_tcb (pd);
- else if (__glibc_unlikely (pd->cancelhandling & SETXID_BITMASK))
+ if (__glibc_unlikely (pd->cancelhandling & SETXID_BITMASK))
{
/* Some other thread might call any of the setXid functions and expect
us to reply. In this case wait until we did that. */
pd->setxid_futex = 0;
}
+ /* If the thread is detached free the TCB. */
+ if (IS_DETACHED (pd))
+ /* Free the TCB. */
+ __free_tcb (pd);
+
/* We cannot call '_exit' here. '_exit' will terminate the process.
The 'exit' implementation in the kernel will signal when the