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v3.5.6
  1#ifndef __ARCH_S390_ATOMIC__
  2#define __ARCH_S390_ATOMIC__
  3
  4/*
  5 * Copyright 1999,2009 IBM Corp.
  6 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
  7 *	      Denis Joseph Barrow,
  8 *	      Arnd Bergmann <arndb@de.ibm.com>,
  9 *
 10 * Atomic operations that C can't guarantee us.
 11 * Useful for resource counting etc.
 12 * s390 uses 'Compare And Swap' for atomicity in SMP environment.
 13 *
 14 */
 15
 
 
 
 16#include <linux/compiler.h>
 17#include <linux/types.h>
 
 18#include <asm/cmpxchg.h>
 19
 20#define ATOMIC_INIT(i)  { (i) }
 21
 22#define __CS_LOOP(ptr, op_val, op_string) ({				\
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 23	int old_val, new_val;						\
 
 
 24	asm volatile(							\
 25		"	l	%0,%2\n"				\
 26		"0:	lr	%1,%0\n"				\
 27		op_string "	%1,%3\n"				\
 28		"	cs	%0,%1,%2\n"				\
 29		"	jl	0b"					\
 30		: "=&d" (old_val), "=&d" (new_val),			\
 31		  "=Q" (((atomic_t *)(ptr))->counter)			\
 32		: "d" (op_val),	 "Q" (((atomic_t *)(ptr))->counter)	\
 33		: "cc", "memory");					\
 34	new_val;							\
 35})
 36
 
 
 37static inline int atomic_read(const atomic_t *v)
 38{
 39	int c;
 40
 41	asm volatile(
 42		"	l	%0,%1\n"
 43		: "=d" (c) : "Q" (v->counter));
 44	return c;
 45}
 46
 47static inline void atomic_set(atomic_t *v, int i)
 48{
 49	asm volatile(
 50		"	st	%1,%0\n"
 51		: "=Q" (v->counter) : "d" (i));
 52}
 53
 54static inline int atomic_add_return(int i, atomic_t *v)
 55{
 56	return __CS_LOOP(v, i, "ar");
 57}
 58#define atomic_add(_i, _v)		atomic_add_return(_i, _v)
 59#define atomic_add_negative(_i, _v)	(atomic_add_return(_i, _v) < 0)
 60#define atomic_inc(_v)			atomic_add_return(1, _v)
 61#define atomic_inc_return(_v)		atomic_add_return(1, _v)
 62#define atomic_inc_and_test(_v)		(atomic_add_return(1, _v) == 0)
 63
 64static inline int atomic_sub_return(int i, atomic_t *v)
 65{
 66	return __CS_LOOP(v, i, "sr");
 
 
 
 
 
 
 
 
 
 
 67}
 68#define atomic_sub(_i, _v)		atomic_sub_return(_i, _v)
 
 
 
 
 
 
 69#define atomic_sub_and_test(_i, _v)	(atomic_sub_return(_i, _v) == 0)
 70#define atomic_dec(_v)			atomic_sub_return(1, _v)
 71#define atomic_dec_return(_v)		atomic_sub_return(1, _v)
 72#define atomic_dec_and_test(_v)		(atomic_sub_return(1, _v) == 0)
 73
 74static inline void atomic_clear_mask(unsigned long mask, atomic_t *v)
 75{
 76	__CS_LOOP(v, ~mask, "nr");
 77}
 78
 79static inline void atomic_set_mask(unsigned long mask, atomic_t *v)
 80{
 81	__CS_LOOP(v, mask, "or");
 82}
 83
 84#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
 85
 86static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
 87{
 88	asm volatile(
 89		"	cs	%0,%2,%1"
 90		: "+d" (old), "=Q" (v->counter)
 91		: "d" (new), "Q" (v->counter)
 92		: "cc", "memory");
 93	return old;
 94}
 95
 96static inline int __atomic_add_unless(atomic_t *v, int a, int u)
 97{
 98	int c, old;
 99	c = atomic_read(v);
100	for (;;) {
101		if (unlikely(c == u))
102			break;
103		old = atomic_cmpxchg(v, c, c + a);
104		if (likely(old == c))
105			break;
106		c = old;
107	}
108	return c;
109}
110
111
112#undef __CS_LOOP
113
114#define ATOMIC64_INIT(i)  { (i) }
115
116#ifdef CONFIG_64BIT
117
118#define __CSG_LOOP(ptr, op_val, op_string) ({				\
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
119	long long old_val, new_val;					\
 
 
120	asm volatile(							\
121		"	lg	%0,%2\n"				\
122		"0:	lgr	%1,%0\n"				\
123		op_string "	%1,%3\n"				\
124		"	csg	%0,%1,%2\n"				\
125		"	jl	0b"					\
126		: "=&d" (old_val), "=&d" (new_val),			\
127		  "=Q" (((atomic_t *)(ptr))->counter)			\
128		: "d" (op_val),	"Q" (((atomic_t *)(ptr))->counter)	\
129		: "cc", "memory");					\
130	new_val;							\
131})
132
 
 
133static inline long long atomic64_read(const atomic64_t *v)
134{
135	long long c;
136
137	asm volatile(
138		"	lg	%0,%1\n"
139		: "=d" (c) : "Q" (v->counter));
140	return c;
141}
142
143static inline void atomic64_set(atomic64_t *v, long long i)
144{
145	asm volatile(
146		"	stg	%1,%0\n"
147		: "=Q" (v->counter) : "d" (i));
148}
149
150static inline long long atomic64_add_return(long long i, atomic64_t *v)
151{
152	return __CSG_LOOP(v, i, "agr");
153}
154
155static inline long long atomic64_sub_return(long long i, atomic64_t *v)
156{
157	return __CSG_LOOP(v, i, "sgr");
 
 
 
 
 
 
 
 
 
 
158}
159
160static inline void atomic64_clear_mask(unsigned long mask, atomic64_t *v)
161{
162	__CSG_LOOP(v, ~mask, "ngr");
163}
164
165static inline void atomic64_set_mask(unsigned long mask, atomic64_t *v)
166{
167	__CSG_LOOP(v, mask, "ogr");
168}
169
170#define atomic64_xchg(v, new) (xchg(&((v)->counter), new))
171
172static inline long long atomic64_cmpxchg(atomic64_t *v,
173					     long long old, long long new)
174{
175	asm volatile(
176		"	csg	%0,%2,%1"
177		: "+d" (old), "=Q" (v->counter)
178		: "d" (new), "Q" (v->counter)
179		: "cc", "memory");
180	return old;
181}
182
183#undef __CSG_LOOP
184
185#else /* CONFIG_64BIT */
186
187typedef struct {
188	long long counter;
189} atomic64_t;
190
191static inline long long atomic64_read(const atomic64_t *v)
192{
193	register_pair rp;
194
195	asm volatile(
196		"	lm	%0,%N0,%1"
197		: "=&d" (rp) : "Q" (v->counter)	);
198	return rp.pair;
199}
200
201static inline void atomic64_set(atomic64_t *v, long long i)
202{
203	register_pair rp = {.pair = i};
204
205	asm volatile(
206		"	stm	%1,%N1,%0"
207		: "=Q" (v->counter) : "d" (rp) );
208}
209
210static inline long long atomic64_xchg(atomic64_t *v, long long new)
211{
212	register_pair rp_new = {.pair = new};
213	register_pair rp_old;
214
215	asm volatile(
216		"	lm	%0,%N0,%1\n"
217		"0:	cds	%0,%2,%1\n"
218		"	jl	0b\n"
219		: "=&d" (rp_old), "=Q" (v->counter)
220		: "d" (rp_new), "Q" (v->counter)
221		: "cc");
222	return rp_old.pair;
223}
224
225static inline long long atomic64_cmpxchg(atomic64_t *v,
226					 long long old, long long new)
227{
228	register_pair rp_old = {.pair = old};
229	register_pair rp_new = {.pair = new};
230
231	asm volatile(
232		"	cds	%0,%2,%1"
233		: "+&d" (rp_old), "=Q" (v->counter)
234		: "d" (rp_new), "Q" (v->counter)
235		: "cc");
236	return rp_old.pair;
237}
238
239
240static inline long long atomic64_add_return(long long i, atomic64_t *v)
241{
242	long long old, new;
243
244	do {
245		old = atomic64_read(v);
246		new = old + i;
247	} while (atomic64_cmpxchg(v, old, new) != old);
248	return new;
249}
250
251static inline long long atomic64_sub_return(long long i, atomic64_t *v)
252{
253	long long old, new;
254
255	do {
256		old = atomic64_read(v);
257		new = old - i;
258	} while (atomic64_cmpxchg(v, old, new) != old);
259	return new;
260}
261
262static inline void atomic64_set_mask(unsigned long long mask, atomic64_t *v)
263{
264	long long old, new;
265
266	do {
267		old = atomic64_read(v);
268		new = old | mask;
269	} while (atomic64_cmpxchg(v, old, new) != old);
270}
271
272static inline void atomic64_clear_mask(unsigned long long mask, atomic64_t *v)
273{
274	long long old, new;
275
276	do {
277		old = atomic64_read(v);
278		new = old & mask;
279	} while (atomic64_cmpxchg(v, old, new) != old);
280}
281
 
 
 
 
 
282#endif /* CONFIG_64BIT */
283
284static inline int atomic64_add_unless(atomic64_t *v, long long a, long long u)
285{
286	long long c, old;
287
288	c = atomic64_read(v);
289	for (;;) {
290		if (unlikely(c == u))
291			break;
292		old = atomic64_cmpxchg(v, c, c + a);
293		if (likely(old == c))
294			break;
295		c = old;
296	}
297	return c != u;
298}
299
300static inline long long atomic64_dec_if_positive(atomic64_t *v)
301{
302	long long c, old, dec;
303
304	c = atomic64_read(v);
305	for (;;) {
306		dec = c - 1;
307		if (unlikely(dec < 0))
308			break;
309		old = atomic64_cmpxchg((v), c, dec);
310		if (likely(old == c))
311			break;
312		c = old;
313	}
314	return dec;
315}
316
317#define atomic64_add(_i, _v)		atomic64_add_return(_i, _v)
318#define atomic64_add_negative(_i, _v)	(atomic64_add_return(_i, _v) < 0)
319#define atomic64_inc(_v)		atomic64_add_return(1, _v)
320#define atomic64_inc_return(_v)		atomic64_add_return(1, _v)
321#define atomic64_inc_and_test(_v)	(atomic64_add_return(1, _v) == 0)
322#define atomic64_sub(_i, _v)		atomic64_sub_return(_i, _v)
 
323#define atomic64_sub_and_test(_i, _v)	(atomic64_sub_return(_i, _v) == 0)
324#define atomic64_dec(_v)		atomic64_sub_return(1, _v)
325#define atomic64_dec_return(_v)		atomic64_sub_return(1, _v)
326#define atomic64_dec_and_test(_v)	(atomic64_sub_return(1, _v) == 0)
327#define atomic64_inc_not_zero(v)	atomic64_add_unless((v), 1, 0)
328
329#define smp_mb__before_atomic_dec()	smp_mb()
330#define smp_mb__after_atomic_dec()	smp_mb()
331#define smp_mb__before_atomic_inc()	smp_mb()
332#define smp_mb__after_atomic_inc()	smp_mb()
333
334#endif /* __ARCH_S390_ATOMIC__  */
v3.15
 
 
 
  1/*
  2 * Copyright IBM Corp. 1999, 2009
  3 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
  4 *	      Denis Joseph Barrow,
  5 *	      Arnd Bergmann <arndb@de.ibm.com>,
  6 *
  7 * Atomic operations that C can't guarantee us.
  8 * Useful for resource counting etc.
  9 * s390 uses 'Compare And Swap' for atomicity in SMP environment.
 10 *
 11 */
 12
 13#ifndef __ARCH_S390_ATOMIC__
 14#define __ARCH_S390_ATOMIC__
 15
 16#include <linux/compiler.h>
 17#include <linux/types.h>
 18#include <asm/barrier.h>
 19#include <asm/cmpxchg.h>
 20
 21#define ATOMIC_INIT(i)  { (i) }
 22
 23#define __ATOMIC_NO_BARRIER	"\n"
 24
 25#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
 26
 27#define __ATOMIC_OR	"lao"
 28#define __ATOMIC_AND	"lan"
 29#define __ATOMIC_ADD	"laa"
 30#define __ATOMIC_BARRIER "bcr	14,0\n"
 31
 32#define __ATOMIC_LOOP(ptr, op_val, op_string, __barrier)		\
 33({									\
 34	int old_val;							\
 35									\
 36	typecheck(atomic_t *, ptr);					\
 37	asm volatile(							\
 38		__barrier						\
 39		op_string "	%0,%2,%1\n"				\
 40		__barrier						\
 41		: "=d" (old_val), "+Q" ((ptr)->counter)			\
 42		: "d" (op_val)						\
 43		: "cc", "memory");					\
 44	old_val;							\
 45})
 46
 47#else /* CONFIG_HAVE_MARCH_Z196_FEATURES */
 48
 49#define __ATOMIC_OR	"or"
 50#define __ATOMIC_AND	"nr"
 51#define __ATOMIC_ADD	"ar"
 52#define __ATOMIC_BARRIER "\n"
 53
 54#define __ATOMIC_LOOP(ptr, op_val, op_string, __barrier)		\
 55({									\
 56	int old_val, new_val;						\
 57									\
 58	typecheck(atomic_t *, ptr);					\
 59	asm volatile(							\
 60		"	l	%0,%2\n"				\
 61		"0:	lr	%1,%0\n"				\
 62		op_string "	%1,%3\n"				\
 63		"	cs	%0,%1,%2\n"				\
 64		"	jl	0b"					\
 65		: "=&d" (old_val), "=&d" (new_val), "+Q" ((ptr)->counter)\
 66		: "d" (op_val)						\
 
 67		: "cc", "memory");					\
 68	old_val;							\
 69})
 70
 71#endif /* CONFIG_HAVE_MARCH_Z196_FEATURES */
 72
 73static inline int atomic_read(const atomic_t *v)
 74{
 75	int c;
 76
 77	asm volatile(
 78		"	l	%0,%1\n"
 79		: "=d" (c) : "Q" (v->counter));
 80	return c;
 81}
 82
 83static inline void atomic_set(atomic_t *v, int i)
 84{
 85	asm volatile(
 86		"	st	%1,%0\n"
 87		: "=Q" (v->counter) : "d" (i));
 88}
 89
 90static inline int atomic_add_return(int i, atomic_t *v)
 91{
 92	return __ATOMIC_LOOP(v, i, __ATOMIC_ADD, __ATOMIC_BARRIER) + i;
 93}
 
 
 
 
 
 94
 95static inline void atomic_add(int i, atomic_t *v)
 96{
 97#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
 98	if (__builtin_constant_p(i) && (i > -129) && (i < 128)) {
 99		asm volatile(
100			"asi	%0,%1\n"
101			: "+Q" (v->counter)
102			: "i" (i)
103			: "cc", "memory");
104		return;
105	}
106#endif
107	__ATOMIC_LOOP(v, i, __ATOMIC_ADD, __ATOMIC_NO_BARRIER);
108}
109
110#define atomic_add_negative(_i, _v)	(atomic_add_return(_i, _v) < 0)
111#define atomic_inc(_v)			atomic_add(1, _v)
112#define atomic_inc_return(_v)		atomic_add_return(1, _v)
113#define atomic_inc_and_test(_v)		(atomic_add_return(1, _v) == 0)
114#define atomic_sub(_i, _v)		atomic_add(-(int)(_i), _v)
115#define atomic_sub_return(_i, _v)	atomic_add_return(-(int)(_i), _v)
116#define atomic_sub_and_test(_i, _v)	(atomic_sub_return(_i, _v) == 0)
117#define atomic_dec(_v)			atomic_sub(1, _v)
118#define atomic_dec_return(_v)		atomic_sub_return(1, _v)
119#define atomic_dec_and_test(_v)		(atomic_sub_return(1, _v) == 0)
120
121static inline void atomic_clear_mask(unsigned int mask, atomic_t *v)
122{
123	__ATOMIC_LOOP(v, ~mask, __ATOMIC_AND, __ATOMIC_NO_BARRIER);
124}
125
126static inline void atomic_set_mask(unsigned int mask, atomic_t *v)
127{
128	__ATOMIC_LOOP(v, mask, __ATOMIC_OR, __ATOMIC_NO_BARRIER);
129}
130
131#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
132
133static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
134{
135	asm volatile(
136		"	cs	%0,%2,%1"
137		: "+d" (old), "+Q" (v->counter)
138		: "d" (new)
139		: "cc", "memory");
140	return old;
141}
142
143static inline int __atomic_add_unless(atomic_t *v, int a, int u)
144{
145	int c, old;
146	c = atomic_read(v);
147	for (;;) {
148		if (unlikely(c == u))
149			break;
150		old = atomic_cmpxchg(v, c, c + a);
151		if (likely(old == c))
152			break;
153		c = old;
154	}
155	return c;
156}
157
158
159#undef __ATOMIC_LOOP
160
161#define ATOMIC64_INIT(i)  { (i) }
162
163#ifdef CONFIG_64BIT
164
165#define __ATOMIC64_NO_BARRIER	"\n"
166
167#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
168
169#define __ATOMIC64_OR	"laog"
170#define __ATOMIC64_AND	"lang"
171#define __ATOMIC64_ADD	"laag"
172#define __ATOMIC64_BARRIER "bcr	14,0\n"
173
174#define __ATOMIC64_LOOP(ptr, op_val, op_string, __barrier)		\
175({									\
176	long long old_val;						\
177									\
178	typecheck(atomic64_t *, ptr);					\
179	asm volatile(							\
180		__barrier						\
181		op_string "	%0,%2,%1\n"				\
182		__barrier						\
183		: "=d" (old_val), "+Q" ((ptr)->counter)			\
184		: "d" (op_val)						\
185		: "cc", "memory");					\
186	old_val;							\
187})
188
189#else /* CONFIG_HAVE_MARCH_Z196_FEATURES */
190
191#define __ATOMIC64_OR	"ogr"
192#define __ATOMIC64_AND	"ngr"
193#define __ATOMIC64_ADD	"agr"
194#define __ATOMIC64_BARRIER "\n"
195
196#define __ATOMIC64_LOOP(ptr, op_val, op_string, __barrier)		\
197({									\
198	long long old_val, new_val;					\
199									\
200	typecheck(atomic64_t *, ptr);					\
201	asm volatile(							\
202		"	lg	%0,%2\n"				\
203		"0:	lgr	%1,%0\n"				\
204		op_string "	%1,%3\n"				\
205		"	csg	%0,%1,%2\n"				\
206		"	jl	0b"					\
207		: "=&d" (old_val), "=&d" (new_val), "+Q" ((ptr)->counter)\
208		: "d" (op_val)						\
 
209		: "cc", "memory");					\
210	old_val;							\
211})
212
213#endif /* CONFIG_HAVE_MARCH_Z196_FEATURES */
214
215static inline long long atomic64_read(const atomic64_t *v)
216{
217	long long c;
218
219	asm volatile(
220		"	lg	%0,%1\n"
221		: "=d" (c) : "Q" (v->counter));
222	return c;
223}
224
225static inline void atomic64_set(atomic64_t *v, long long i)
226{
227	asm volatile(
228		"	stg	%1,%0\n"
229		: "=Q" (v->counter) : "d" (i));
230}
231
232static inline long long atomic64_add_return(long long i, atomic64_t *v)
233{
234	return __ATOMIC64_LOOP(v, i, __ATOMIC64_ADD, __ATOMIC64_BARRIER) + i;
235}
236
237static inline void atomic64_add(long long i, atomic64_t *v)
238{
239#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
240	if (__builtin_constant_p(i) && (i > -129) && (i < 128)) {
241		asm volatile(
242			"agsi	%0,%1\n"
243			: "+Q" (v->counter)
244			: "i" (i)
245			: "cc", "memory");
246		return;
247	}
248#endif
249	__ATOMIC64_LOOP(v, i, __ATOMIC64_ADD, __ATOMIC64_NO_BARRIER);
250}
251
252static inline void atomic64_clear_mask(unsigned long mask, atomic64_t *v)
253{
254	__ATOMIC64_LOOP(v, ~mask, __ATOMIC64_AND, __ATOMIC64_NO_BARRIER);
255}
256
257static inline void atomic64_set_mask(unsigned long mask, atomic64_t *v)
258{
259	__ATOMIC64_LOOP(v, mask, __ATOMIC64_OR, __ATOMIC64_NO_BARRIER);
260}
261
262#define atomic64_xchg(v, new) (xchg(&((v)->counter), new))
263
264static inline long long atomic64_cmpxchg(atomic64_t *v,
265					     long long old, long long new)
266{
267	asm volatile(
268		"	csg	%0,%2,%1"
269		: "+d" (old), "+Q" (v->counter)
270		: "d" (new)
271		: "cc", "memory");
272	return old;
273}
274
275#undef __ATOMIC64_LOOP
276
277#else /* CONFIG_64BIT */
278
279typedef struct {
280	long long counter;
281} atomic64_t;
282
283static inline long long atomic64_read(const atomic64_t *v)
284{
285	register_pair rp;
286
287	asm volatile(
288		"	lm	%0,%N0,%1"
289		: "=&d" (rp) : "Q" (v->counter)	);
290	return rp.pair;
291}
292
293static inline void atomic64_set(atomic64_t *v, long long i)
294{
295	register_pair rp = {.pair = i};
296
297	asm volatile(
298		"	stm	%1,%N1,%0"
299		: "=Q" (v->counter) : "d" (rp) );
300}
301
302static inline long long atomic64_xchg(atomic64_t *v, long long new)
303{
304	register_pair rp_new = {.pair = new};
305	register_pair rp_old;
306
307	asm volatile(
308		"	lm	%0,%N0,%1\n"
309		"0:	cds	%0,%2,%1\n"
310		"	jl	0b\n"
311		: "=&d" (rp_old), "+Q" (v->counter)
312		: "d" (rp_new)
313		: "cc");
314	return rp_old.pair;
315}
316
317static inline long long atomic64_cmpxchg(atomic64_t *v,
318					 long long old, long long new)
319{
320	register_pair rp_old = {.pair = old};
321	register_pair rp_new = {.pair = new};
322
323	asm volatile(
324		"	cds	%0,%2,%1"
325		: "+&d" (rp_old), "+Q" (v->counter)
326		: "d" (rp_new)
327		: "cc");
328	return rp_old.pair;
329}
330
331
332static inline long long atomic64_add_return(long long i, atomic64_t *v)
333{
334	long long old, new;
335
336	do {
337		old = atomic64_read(v);
338		new = old + i;
339	} while (atomic64_cmpxchg(v, old, new) != old);
340	return new;
341}
342
 
 
 
 
 
 
 
 
 
 
 
343static inline void atomic64_set_mask(unsigned long long mask, atomic64_t *v)
344{
345	long long old, new;
346
347	do {
348		old = atomic64_read(v);
349		new = old | mask;
350	} while (atomic64_cmpxchg(v, old, new) != old);
351}
352
353static inline void atomic64_clear_mask(unsigned long long mask, atomic64_t *v)
354{
355	long long old, new;
356
357	do {
358		old = atomic64_read(v);
359		new = old & mask;
360	} while (atomic64_cmpxchg(v, old, new) != old);
361}
362
363static inline void atomic64_add(long long i, atomic64_t *v)
364{
365	atomic64_add_return(i, v);
366}
367
368#endif /* CONFIG_64BIT */
369
370static inline int atomic64_add_unless(atomic64_t *v, long long i, long long u)
371{
372	long long c, old;
373
374	c = atomic64_read(v);
375	for (;;) {
376		if (unlikely(c == u))
377			break;
378		old = atomic64_cmpxchg(v, c, c + i);
379		if (likely(old == c))
380			break;
381		c = old;
382	}
383	return c != u;
384}
385
386static inline long long atomic64_dec_if_positive(atomic64_t *v)
387{
388	long long c, old, dec;
389
390	c = atomic64_read(v);
391	for (;;) {
392		dec = c - 1;
393		if (unlikely(dec < 0))
394			break;
395		old = atomic64_cmpxchg((v), c, dec);
396		if (likely(old == c))
397			break;
398		c = old;
399	}
400	return dec;
401}
402
 
403#define atomic64_add_negative(_i, _v)	(atomic64_add_return(_i, _v) < 0)
404#define atomic64_inc(_v)		atomic64_add(1, _v)
405#define atomic64_inc_return(_v)		atomic64_add_return(1, _v)
406#define atomic64_inc_and_test(_v)	(atomic64_add_return(1, _v) == 0)
407#define atomic64_sub_return(_i, _v)	atomic64_add_return(-(long long)(_i), _v)
408#define atomic64_sub(_i, _v)		atomic64_add(-(long long)(_i), _v)
409#define atomic64_sub_and_test(_i, _v)	(atomic64_sub_return(_i, _v) == 0)
410#define atomic64_dec(_v)		atomic64_sub(1, _v)
411#define atomic64_dec_return(_v)		atomic64_sub_return(1, _v)
412#define atomic64_dec_and_test(_v)	(atomic64_sub_return(1, _v) == 0)
413#define atomic64_inc_not_zero(v)	atomic64_add_unless((v), 1, 0)
414
415#define smp_mb__before_atomic_dec()	smp_mb()
416#define smp_mb__after_atomic_dec()	smp_mb()
417#define smp_mb__before_atomic_inc()	smp_mb()
418#define smp_mb__after_atomic_inc()	smp_mb()
419
420#endif /* __ARCH_S390_ATOMIC__  */