On Thu, Jan 26, 2017 at 06:01:09PM +0100, Sebastian Andrzej Siewior wrote: > On 2017-01-24 18:45:50 [-0800], Alex Goins wrote: > > mutex_destroy is no-op inline when DEBUG_MUTEX is not enabled. The RT Linux > > patches replace mutex_destroy() with rt_mutex_destroy(). This patch aligns > > rt_mutex_destroy() with mutex_destroy() by using the same no-op inline > > technique. > > > > Signed-off-by: Alex Goins <agoins@xxxxxxxxxx> > > Reviewed-by: Andy Ritger <aritger@xxxxxxxxxx> > > So what is the problem? Why are we doing this? There is still a check to > see if the lock is in use which is also done for the case where > DEBUG_MUTEX is disabled. The problem is that various static inline functions such as reservation_object_fini() indirectly call mutex_destroy. On DEBUG_MUTEX kernels, mutex_destroy is EXPORT_SYMBOL_GPL. In upstream, non-DEBUG_MUTEX kernels define mutex_destroy to a noop. This gives users the option of disabling DEBUG_MUTEX if they want to use non-GPL, reservation_object_fini()-using, kernel modules. In PREEMPTRT, non-DEBUG_MUTEX kernels export rt_mutex_destroy as EXPORT_SYMBOL_GPL, so users no longer have the work around of using DEBUG_MUTEX. This patch gives PREEMPTRT users the option of disabling DEBUG_MUTEX if they want to use such kernel modules, matching upstream behavior. -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
