Commit ecf51c9f authored by Vineet Gupta's avatar Vineet Gupta
Browse files

ARC: xchg: !LLSC: remove UP micro-optimization/hack 



It gets in the way of cleaning things up and is a maintenance
pain-in-neck !

Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarVineet Gupta <vgupta@kernel.org>
parent 9d011e12

arch/arc/include/asm/cmpxchg.h

+1 −7
Original line number Diff line number Diff line
@@ -113,15 +113,9 @@ static inline unsigned long __xchg(unsigned long val, volatile void *ptr, 
 *  - For !LLSC, cmpxchg() needs to use that lock (see above) and there is lot

 *    of  kernel code which calls xchg()/cmpxchg() on same data (see llist.h)

 *    Hence xchg() needs to follow same locking rules.

 *

 * Technically the lock is also needed for UP (boils down to irq save/restore)

 * but we can cheat a bit since cmpxchg() atomic_ops_lock() would cause irqs to

 * be disabled thus can't possibly be interrupted/preempted/clobbered by xchg()

 * Other way around, xchg is one instruction anyways, so can't be interrupted

 * as such

 */



#if !defined(CONFIG_ARC_HAS_LLSC) && defined(CONFIG_SMP)

#ifndef CONFIG_ARC_HAS_LLSC



#define arch_xchg(ptr, with)		\

({					\