[PATCH 15/17] futex: Drop hb->lock before enqueueing on the rtmutex

From: Peter Zijlstra commit 56222b212e8edb1cf51f5dd73ff645809b082b40 upstream. When PREEMPT_RT_FULL does the spinlock -> rt_mutex substitution the PI chain code will (falsely) report a deadlock and BUG. The problem is that it hold hb->lock (now an rt_mutex) while doing task_blocks_on_rt_mutex

[PATCH 15/17] futex: Drop hb->lock before enqueueing on the rtmutex

From: Peter Zijlstra commit 56222b212e8edb1cf51f5dd73ff645809b082b40 upstream. When PREEMPT_RT_FULL does the spinlock -> rt_mutex substitution the PI chain code will (falsely) report a deadlock and BUG. The problem is that it hold hb->lock (now an rt_mutex) while doing task_blocks_on_rt_mutex