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

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

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Vineet Gupta <vgupta@kernel.org>
This commit is contained in:
Vineet Gupta 2020-05-06 14:41:12 -07:00
parent 9d011e1207
commit ecf51c9fa0
1 changed files with 1 additions and 7 deletions
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8
arch/arc/include/asm/cmpxchg.h
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@ -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) \
({ \