Re: [v4] powerpc: spinlock: Fix spin_unlock_wait()

2016-06-20 Thread Michael Ellerman
On Fri, 2016-10-06 at 03:51:28 UTC, Boqun Feng wrote: > There is an ordering issue with spin_unlock_wait() on powerpc, because > the spin_lock primitive is an ACQUIRE and an ACQUIRE is only ordering > the load part of the operation with memory operations following it. ... > > Suggested-by: "Paul E

[PATCH v4] powerpc: spinlock: Fix spin_unlock_wait()

2016-06-09 Thread Boqun Feng
There is an ordering issue with spin_unlock_wait() on powerpc, because the spin_lock primitive is an ACQUIRE and an ACQUIRE is only ordering the load part of the operation with memory operations following it. Therefore the following event sequence can happen: CPU 1 CPU 2