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shared data protection failed in pthread_cond_timedwait


I have 22 threads wait in pthread_cond_timedwait. When they are all woke up, I found 
there are more than one threads can access shared data in pthread_cond_timedwait.

I added print messages as follow code:

--- libc/nptl/pthread_cond_timedwait.c
+++ libc/nptl/pthread_cond_timedwait.c
@@ -34,6 +34,7 @@
 # include <bits/libc-vdso.h>
+#include <stdio.h>

 /* Cleanup handler, defined in pthread_cond_wait.c.  */
 extern void __condvar_cleanup (void *arg)
@@ -235,7 +239,9 @@


+printf("start do sub :%d, lock:%d %p\n", cond->__data.__nwaiters, cond->__data.__lock, pthread_self());
   cond->__data.__nwaiters -= 1 << COND_NWAITERS_SHIFT;
+printf("end do sub :%d, lock:%d %p\n", cond->__data.__nwaiters, cond->__data.__lock, pthread_self());

   /* If pthread_cond_destroy was called on this variable already,
      notify the pthread_cond_destroy caller all waiters have left

I tested on Linux arma15el 3.10.37+ #2 SMP Fri Apr 25 11:23:25 CST 2014 armv7l GNU/Linux.
Here is the result:

start do sub :45, lock:1 0xb6d9a460
end do sub :43, lock:1 0xb6d9a460
start do sub :43, lock:1 0xb6d9e460
end do sub :41, lock:2 0xb6d9e460
start do sub :43, lock:2 0xb6dbe460    //two threads both access the shared data
start do sub :41, lock:1 0xb6daa460
end do sub :39, lock:2 0xb6daa460
start do sub :39, lock:2 0xb6de6460
end do sub :37, lock:2 0xb6de6460
start do sub :37, lock:2 0xb6db6460
end do sub :35, lock:2 0xb6db6460
start do sub :35, lock:2 0xb6dc2460
end do sub :33, lock:2 0xb6dc2460
end do sub :37, lock:2 0xb6dbe460
start do sub :33, lock:2 0xb6dc6460
end do sub :31, lock:0 0xb6dc6460
start do sub :31, lock:2 0xb6dae460
end do sub :29, lock:2 0xb6dae460
start do sub :29, lock:2 0xb6db2460
end do sub :27, lock:2 0xb6db2460
start do sub :27, lock:2 0xb6dba460
end do sub :25, lock:2 0xb6dba460
start do sub :25, lock:2 0xb6da2460
end do sub :23, lock:2 0xb6da2460

Is lll_lock (cond->__data.__lock, pshared) failed?

pshared is LLL_SHARED.

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