[RFC][BZ #16549] Add sanity check for condvar alignment.

[Roland McGrath]

> On Tue, Feb 11, 2014 at 09:21:11AM -0800, Roland McGrath wrote:
> > > +  assert (((uintptr_t) cond) % sizeof (long) == 0);
> > 
> > Drop superfluous parens.  Use __alignof (pthread_cond_t).
> 
> OK now?
> 
> 	* nptl/pthread_cond_init.c (__pthread_cond_init): Add assert that
> 	input is aligned.

Looks fine.

> diff --git a/nptl/pthread_cond_init.c b/nptl/pthread_cond_init.c
> index 27efc9c..6fa522a 100644
> --- a/nptl/pthread_cond_init.c
> +++ b/nptl/pthread_cond_init.c
> @@ -16,6 +16,7 @@
>     License along with the GNU C Library; if not, see
>     <http://www.gnu.org/licenses/>.  */
>  
> +#include <assert.h>
>  #include <shlib-compat.h>
>  #include "pthreadP.h"
>  #include <stap-probe.h>
> @@ -28,6 +29,7 @@ __pthread_cond_init (cond, cond_attr)
>  {
>    struct pthread_condattr *icond_attr = (struct pthread_condattr *) cond_attr;
> 
> +  assert ((uintptr_t) cond % __alignof (pthread_cond_t) == 0);
>    cond->__data.__lock = LLL_LOCK_INITIALIZER;
>    cond->__data.__futex = 0;
>    cond->__data.__nwaiters = (icond_attr != NULL