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kernel/linux-rt-4.4.41/arch/sparc/include/asm/cmpxchg_32.h 2.25 KB
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  /* 32-bit atomic xchg() and cmpxchg() definitions.
   *
   * Copyright (C) 1996 David S. Miller (davem@davemloft.net)
   * Copyright (C) 2000 Anton Blanchard (anton@linuxcare.com.au)
   * Copyright (C) 2007 Kyle McMartin (kyle@parisc-linux.org)
   *
   * Additions by Keith M Wesolowski (wesolows@foobazco.org) based
   * on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf <prumpf@tux.org>.
   */
  
  #ifndef __ARCH_SPARC_CMPXCHG__
  #define __ARCH_SPARC_CMPXCHG__
  
  unsigned long __xchg_u32(volatile u32 *m, u32 new);
  void __xchg_called_with_bad_pointer(void);
  
  static inline unsigned long __xchg(unsigned long x, __volatile__ void * ptr, int size)
  {
  	switch (size) {
  	case 4:
  		return __xchg_u32(ptr, x);
  	}
  	__xchg_called_with_bad_pointer();
  	return x;
  }
  
  #define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
  
  /* Emulate cmpxchg() the same way we emulate atomics,
   * by hashing the object address and indexing into an array
   * of spinlocks to get a bit of performance...
   *
   * See arch/sparc/lib/atomic32.c for implementation.
   *
   * Cribbed from <asm-parisc/atomic.h>
   */
  
  /* bug catcher for when unsupported size is used - won't link */
  void __cmpxchg_called_with_bad_pointer(void);
  /* we only need to support cmpxchg of a u32 on sparc */
  unsigned long __cmpxchg_u32(volatile u32 *m, u32 old, u32 new_);
  
  /* don't worry...optimizer will get rid of most of this */
  static inline unsigned long
  __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
  {
  	switch (size) {
  	case 4:
  		return __cmpxchg_u32((u32 *)ptr, (u32)old, (u32)new_);
  	default:
  		__cmpxchg_called_with_bad_pointer();
  		break;
  	}
  	return old;
  }
  
  #define cmpxchg(ptr, o, n)						\
  ({									\
  	__typeof__(*(ptr)) _o_ = (o);					\
  	__typeof__(*(ptr)) _n_ = (n);					\
  	(__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,	\
  			(unsigned long)_n_, sizeof(*(ptr)));		\
  })
  
  #include <asm-generic/cmpxchg-local.h>
  
  /*
   * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
   * them available.
   */
  #define cmpxchg_local(ptr, o, n)				  	       \
  	((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
  			(unsigned long)(n), sizeof(*(ptr))))
  #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
  
  #endif /* __ARCH_SPARC_CMPXCHG__ */