aboutsummaryrefslogtreecommitdiffstats
path: root/kernel/posix-timers.c
blob: ea55c7a1cd75a3dbaa50040b3d55255c12a5786f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
/*
 * linux/kernel/posix_timers.c
 *
 *
 * 2002-10-15  Posix Clocks & timers
 *                           by George Anzinger george@mvista.com
 *
 *			     Copyright (C) 2002 2003 by MontaVista Software.
 *
 * 2004-06-01  Fix CLOCK_REALTIME clock/timer TIMER_ABSTIME bug.
 *			     Copyright (C) 2004 Boris Hu
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * MontaVista Software | 1237 East Arques Avenue | Sunnyvale | CA 94085 | USA
 */

/* These are all the functions necessary to implement
 * POSIX clocks & timers
 */
#include <linux/mm.h>
#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/time.h>

#include <asm/uaccess.h>
#include <asm/semaphore.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/compiler.h>
#include <linux/idr.h>
#include <linux/posix-timers.h>
#include <linux/syscalls.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
#include <linux/module.h>

#ifndef div_long_long_rem
#include <asm/div64.h>

#define div_long_long_rem(dividend,divisor,remainder) ({ \
		       u64 result = dividend;		\
		       *remainder = do_div(result,divisor); \
		       result; })

#endif
#define CLOCK_REALTIME_RES TICK_NSEC  /* In nano seconds. */

static inline u64  mpy_l_X_l_ll(unsigned long mpy1,unsigned long mpy2)
{
	return (u64)mpy1 * mpy2;
}
/*
 * Management arrays for POSIX timers.	 Timers are kept in slab memory
 * Timer ids are allocated by an external routine that keeps track of the
 * id and the timer.  The external interface is:
 *
 * void *idr_find(struct idr *idp, int id);           to find timer_id <id>
 * int idr_get_new(struct idr *idp, void *ptr);       to get a new id and
 *                                                    related it to <ptr>
 * void idr_remove(struct idr *idp, int id);          to release <id>
 * void idr_init(struct idr *idp);                    to initialize <idp>
 *                                                    which we supply.
 * The idr_get_new *may* call slab for more memory so it must not be
 * called under a spin lock.  Likewise idr_remore may release memory
 * (but it may be ok to do this under a lock...).
 * idr_find is just a memory look up and is quite fast.  A -1 return
 * indicates that the requested id does not exist.
 */

/*
 * Lets keep our timers in a slab cache :-)
 */
static kmem_cache_t *posix_timers_cache;
static struct idr posix_timers_id;
static DEFINE_SPINLOCK(idr_lock);

/*
 * we assume that the new SIGEV_THREAD_ID shares no bits with the other
 * SIGEV values.  Here we put out an error if this assumption fails.
 */
#if SIGEV_THREAD_ID != (SIGEV_THREAD_ID & \
                       ~(SIGEV_SIGNAL | SIGEV_NONE | SIGEV_THREAD))
#error "SIGEV_THREAD_ID must not share bit with other SIGEV values!"
#endif


/*
 * The timer ID is turned into a timer address by idr_find().
 * Verifying a valid ID consists of:
 *
 * a) checking that idr_find() returns other than -1.
 * b) checking that the timer id matches the one in the timer itself.
 * c) that the timer owner is in the callers thread group.
 */

/*
 * CLOCKs: The POSIX standard calls for a couple of clocks and allows us
 *	    to implement others.  This structure defines the various
 *	    clocks and allows the possibility of adding others.	 We
 *	    provide an interface to add clocks to the table and expect
 *	    the "arch" code to add at least one clock that is high
 *	    resolution.	 Here we define the standard CLOCK_REALTIME as a
 *	    1/HZ resolution clock.
 *
 * RESOLUTION: Clock resolution is used to round up timer and interval
 *	    times, NOT to report clock times, which are reported with as
 *	    much resolution as the system can muster.  In some cases this
 *	    resolution may depend on the underlying clock hardware and
 *	    may not be quantifiable until run time, and only then is the
 *	    necessary code is written.	The standard says we should say
 *	    something about this issue in the documentation...
 *
 * FUNCTIONS: The CLOCKs structure defines possible functions to handle
 *	    various clock functions.  For clocks that use the standard
 *	    system timer code these entries should be NULL.  This will
 *	    allow dispatch without the overhead of indirect function
 *	    calls.  CLOCKS that depend on other sources (e.g. WWV or GPS)
 *	    must supply functions here, even if the function just returns
 *	    ENOSYS.  The standard POSIX timer management code assumes the
 *	    following: 1.) The k_itimer struct (sched.h) is used for the
 *	    timer.  2.) The list, it_lock, it_clock, it_id and it_process
 *	    fields are not modified by timer code.
 *
 *          At this time all functions EXCEPT clock_nanosleep can be
 *          redirected by the CLOCKS structure.  Clock_nanosleep is in
 *          there, but the code ignores it.
 *
 * Permissions: It is assumed that the clock_settime() function defined
 *	    for each clock will take care of permission checks.	 Some
 *	    clocks may be set able by any user (i.e. local process
 *	    clocks) others not.	 Currently the only set able clock we
 *	    have is CLOCK_REALTIME and its high res counter part, both of
 *	    which we beg off on and pass to do_sys_settimeofday().
 */

static struct k_clock posix_clocks[MAX_CLOCKS];
/*
 * We only have one real clock that can be set so we need only one abs list,
 * even if we should want to have several clocks with differing resolutions.
 */
static struct k_clock_abs abs_list = {.list = LIST_HEAD_INIT(abs_list.list),
				      .lock = SPIN_LOCK_UNLOCKED};

static void posix_timer_fn(unsigned long);
static u64 do_posix_clock_monotonic_gettime_parts(
	struct timespec *tp, struct timespec *mo);
int do_posix_clock_monotonic_gettime(struct timespec *tp);
static int do_posix_clock_monotonic_get(clockid_t, struct timespec *tp);

static struct k_itimer *lock_timer(timer_t timer_id, unsigned long *flags);

static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
{
	spin_unlock_irqrestore(&timr->it_lock, flags);
}

/*
 * Call the k_clock hook function if non-null, or the default function.
 */
#define CLOCK_DISPATCH(clock, call, arglist) \
 	((clock) < 0 ? posix_cpu_##call arglist : \
 	 (posix_clocks[clock].call != NULL \
 	  ? (*posix_clocks[clock].call) arglist : common_##call arglist))

/*
 * Default clock hook functions when the struct k_clock passed
 * to register_posix_clock leaves a function pointer null.
 *
 * The function common_CALL is the default implementation for
 * the function pointer CALL in struct k_clock.
 */

static inline int common_clock_getres(clockid_t which_clock,
				      struct timespec *tp)
{
	tp->tv_sec = 0;
	tp->tv_nsec = posix_clocks[which_clock].res;
	return 0;
}

static inline int common_clock_get(clockid_t which_clock, struct timespec *tp)
{
	getnstimeofday(tp);
	return 0;
}

static inline int common_clock_set(clockid_t which_clock, struct timespec *tp)
{
	return do_sys_settimeofday(tp, NULL);
}

static inline int common_timer_create(struct k_itimer *new_timer)
{
	INIT_LIST_HEAD(&new_timer->it.real.abs_timer_entry);
	init_timer(&new_timer->it.real.timer);
	new_timer->it.real.timer.data = (unsigned long) new_timer;
	new_timer->it.real.timer.function = posix_timer_fn;
	return 0;
}

/*
 * These ones are defined below.
 */
static int common_nsleep(clockid_t, int flags, struct timespec *t);
static void common_timer_get(struct k_itimer *, struct itimerspec *);
static int common_timer_set(struct k_itimer *, int,
			    struct itimerspec *, struct itimerspec *);
static int common_timer_del(struct k_itimer *timer);

/*
 * Return nonzero iff we know a priori this clockid_t value is bogus.
 */
static inline int invalid_clockid(clockid_t which_clock)
{
	if (which_clock < 0)	/* CPU clock, posix_cpu_* will check it */
		return 0;
	if ((unsigned) which_clock >= MAX_CLOCKS)
		return 1;
	if (posix_clocks[which_clock].clock_getres != NULL)
		return 0;
#ifndef CLOCK_DISPATCH_DIRECT
	if (posix_clocks[which_clock].res != 0)
		return 0;
#endif
	return 1;
}


/*
 * Initialize everything, well, just everything in Posix clocks/timers ;)
 */
static __init int init_posix_timers(void)
{
	struct k_clock clock_realtime = {.res = CLOCK_REALTIME_RES,
					 .abs_struct = &abs_list
	};
	struct k_clock clock_monotonic = {.res = CLOCK_REALTIME_RES,
		.abs_struct = NULL,
		.clock_get = do_posix_clock_monotonic_get,
		.clock_set = do_posix_clock_nosettime
	};

	register_posix_clock(CLOCK_REALTIME, &clock_realtime);
	register_posix_clock(CLOCK_MONOTONIC, &clock_monotonic);

	posix_timers_cache = kmem_cache_create("posix_timers_cache",
					sizeof (struct k_itimer), 0, 0, NULL, NULL);
	idr_init(&posix_timers_id);
	return 0;
}

__initcall(init_posix_timers);

static void tstojiffie(struct timespec *tp, int res, u64 *jiff)
{
	long sec = tp->tv_sec;
	long nsec = tp->tv_nsec + res - 1;

	if (nsec > NSEC_PER_SEC) {
		sec++;
		nsec -= NSEC_PER_SEC;
	}

	/*
	 * The scaling constants are defined in <linux/time.h>
	 * The difference between there and here is that we do the
	 * res rounding and compute a 64-bit result (well so does that
	 * but it then throws away the high bits).
  	 */
	*jiff =  (mpy_l_X_l_ll(sec, SEC_CONVERSION) +
		  (mpy_l_X_l_ll(nsec, NSEC_CONVERSION) >> 
		   (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
}

/*
 * This function adjusts the timer as needed as a result of the clock
 * being set.  It should only be called for absolute timers, and then
 * under the abs_list lock.  It computes the time difference and sets
 * the new jiffies value in the timer.  It also updates the timers
 * reference wall_to_monotonic value.  It is complicated by the fact
 * that tstojiffies() only handles positive times and it needs to work
 * with both positive and negative times.  Also, for negative offsets,
 * we need to defeat the res round up.
 *
 * Return is true if there is a new time, else false.
 */
static long add_clockset_delta(struct k_itimer *timr,
			       struct timespec *new_wall_to)
{
	struct timespec delta;
	int sign = 0;
	u64 exp;

	set_normalized_timespec(&delta,
				new_wall_to->tv_sec -
				timr->it.real.wall_to_prev.tv_sec,
				new_wall_to->tv_nsec -
				timr->it.real.wall_to_prev.tv_nsec);
	if (likely(!(delta.tv_sec | delta.tv_nsec)))
		return 0;
	if (delta.tv_sec < 0) {
		set_normalized_timespec(&delta,
					-delta.tv_sec,
					1 - delta.tv_nsec -
					posix_clocks[timr->it_clock].res);
		sign++;
	}
	tstojiffie(&delta, posix_clocks[timr->it_clock].res, &exp);
	timr->it.real.wall_to_prev = *new_wall_to;
	timr->it.real.timer.expires += (sign ? -exp : exp);
	return 1;
}

static void remove_from_abslist(struct k_itimer *timr)
{
	if (!list_empty(&timr->it.real.abs_timer_entry)) {
		spin_lock(&abs_list.lock);
		list_del_init(&timr->it.real.abs_timer_entry);
		spin_unlock(&abs_list.lock);
	}
}

static void schedule_next_timer(struct k_itimer *timr)
{
	struct timespec new_wall_to;
	struct now_struct now;
	unsigned long seq;

	/*
	 * Set up the timer for the next interval (if there is one).
	 * Note: this code uses the abs_timer_lock to protect
	 * it.real.wall_to_prev and must hold it until exp is set, not exactly
	 * obvious...

	 * This function is used for CLOCK_REALTIME* and
	 * CLOCK_MONOTONIC* timers.  If we ever want to handle other
	 * CLOCKs, the calling code (do_schedule_next_timer) would need
	 * to pull the "clock" info from the timer and dispatch the
	 * "other" CLOCKs "next timer" code (which, I suppose should
	 * also be added to the k_clock structure).
	 */
	if (!timr->it.real.incr)
		return;

	do {
		seq = read_seqbegin(&xtime_lock);
		new_wall_to =	wall_to_monotonic;
		posix_get_now(&now);
	} while (read_seqretry(&xtime_lock, seq));

	if (!list_empty(&timr->it.real.abs_timer_entry)) {
		spin_lock(&abs_list.lock);
		add_clockset_delta(timr, &new_wall_to);

		posix_bump_timer(timr, now);

		spin_unlock(&abs_list.lock);
	} else {
		posix_bump_timer(timr, now);
	}
	timr->it_overrun_last = timr->it_overrun;
	timr->it_overrun = -1;
	++timr->it_requeue_pending;
	add_timer(&timr->it.real.timer);
}

/*
 * This function is exported for use by the signal deliver code.  It is
 * called just prior to the info block being released and passes that
 * block to us.  It's function is to update the overrun entry AND to
 * restart the timer.  It should only be called if the timer is to be
 * restarted (i.e. we have flagged this in the sys_private entry of the
 * info block).
 *
 * To protect aginst the timer going away while the interrupt is queued,
 * we require that the it_requeue_pending flag be set.
 */
void do_schedule_next_timer(struct siginfo *info)
{
	struct k_itimer *timr;
	unsigned long flags;

	timr = lock_timer(info->si_tid, &flags);

	if (!timr || timr->it_requeue_pending != info->si_sys_private)
		goto exit;

	if (timr->it_clock < 0)	/* CPU clock */
		posix_cpu_timer_schedule(timr);
	else
		schedule_next_timer(timr);
	info->si_overrun = timr->it_overrun_last;
exit:
	if (timr)
		unlock_timer(timr, flags);
}

int posix_timer_event(struct k_itimer *timr,int si_private)
{
	memset(&timr->sigq->info, 0, sizeof(siginfo_t));
	timr->sigq->info.si_sys_private = si_private;
	/*
	 * Send signal to the process that owns this timer.

	 * This code assumes that all the possible abs_lists share the
	 * same lock (there is only one list at this time). If this is
	 * not the case, the CLOCK info would need to be used to find
	 * the proper abs list lock.
	 */

	timr->sigq->info.si_signo = timr->it_sigev_signo;
	timr->sigq->info.si_errno = 0;
	timr->sigq->info.si_code = SI_TIMER;
	timr->sigq->info.si_tid = timr->it_id;
	timr->sigq->info.si_value = timr->it_sigev_value;

	if (timr->it_sigev_notify & SIGEV_THREAD_ID) {
		struct task_struct *leader;
		int ret = send_sigqueue(timr->it_sigev_signo, timr->sigq,
					timr->it_process);

		if (likely(ret >= 0))
			return ret;

		timr->it_sigev_notify = SIGEV_SIGNAL;
		leader = timr->it_process->group_leader;
		put_task_struct(timr->it_process);
		timr->it_process = leader;
	}

	return send_group_sigqueue(timr->it_sigev_signo, timr->sigq,
				   timr->it_process);
}
EXPORT_SYMBOL_GPL(posix_timer_event);

/*
 * This function gets called when a POSIX.1b interval timer expires.  It
 * is used as a callback from the kernel internal timer.  The
 * run_timer_list code ALWAYS calls with interrupts on.

 * This code is for CLOCK_REALTIME* and CLOCK_MONOTONIC* timers.
 */
static void posix_timer_fn(unsigned long __data)
{
	struct k_itimer *timr = (struct k_itimer *) __data;
	unsigned long flags;
	unsigned long seq;
	struct timespec delta, new_wall_to;
	u64 exp = 0;
	int do_notify = 1;

	spin_lock_irqsave(&timr->it_lock, flags);
	if (!list_empty(&timr->it.real.abs_timer_entry)) {
		spin_lock(&abs_list.lock);
		do {
			seq = read_seqbegin(&xtime_lock);
			new_wall_to =	wall_to_monotonic;
		} while (read_seqretry(&xtime_lock, seq));
		set_normalized_timespec(&delta,
					new_wall_to.tv_sec -
					timr->it.real.wall_to_prev.tv_sec,
					new_wall_to.tv_nsec -
					timr->it.real.wall_to_prev.tv_nsec);
		if (likely((delta.tv_sec | delta.tv_nsec ) == 0)) {
			/* do nothing, timer is on time */
		} else if (delta.tv_sec < 0) {
			/* do nothing, timer is already late */
		} else {
			/* timer is early due to a clock set */
			tstojiffie(&delta,
				   posix_clocks[timr->it_clock].res,
				   &exp);
			timr->it.real.wall_to_prev = new_wall_to;
			timr->it.real.timer.expires += exp;
			add_timer(&timr->it.real.timer);
			do_notify = 0;
		}
		spin_unlock(&abs_list.lock);

	}
	if (do_notify)  {
		int si_private=0;

		if (timr->it.real.incr)
			si_private = ++timr->it_requeue_pending;
		else {
			remove_from_abslist(timr);
		}

		if (posix_timer_event(timr, si_private))
			/*
			 * signal was not sent because of sig_ignor
			 * we will not get a call back to restart it AND
			 * it should be restarted.
			 */
			schedule_next_timer(timr);
	}
	unlock_timer(timr, flags); /* hold thru abs lock to keep irq off */
}


static inline struct task_struct * good_sigevent(sigevent_t * event)
{
	struct task_struct *rtn = current->group_leader;

	if ((event->sigev_notify & SIGEV_THREAD_ID ) &&
		(!(rtn = find_task_by_pid(event->sigev_notify_thread_id)) ||
		 rtn->tgid != current->tgid ||
		 (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL))
		return NULL;

	if (((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) &&
	    ((event->sigev_signo <= 0) || (event->sigev_signo > SIGRTMAX)))
		return NULL;

	return rtn;
}

void register_posix_clock(clockid_t clock_id, struct k_clock *new_clock)
{
	if ((unsigned) clock_id >= MAX_CLOCKS) {
		printk("POSIX clock register failed for clock_id %d\n",
		       clock_id);
		return;
	}

	posix_clocks[clock_id] = *new_clock;
}
EXPORT_SYMBOL_GPL(register_posix_clock);

static struct k_itimer * alloc_posix_timer(void)
{
	struct k_itimer *tmr;
	tmr = kmem_cache_alloc(posix_timers_cache, GFP_KERNEL);
	if (!tmr)
		return tmr;
	memset(tmr, 0, sizeof (struct k_itimer));
	if (unlikely(!(tmr->sigq = sigqueue_alloc()))) {
		kmem_cache_free(posix_timers_cache, tmr);
		tmr = NULL;
	}
	return tmr;
}

#define IT_ID_SET	1
#define IT_ID_NOT_SET	0
static void release_posix_timer(struct k_itimer *tmr, int it_id_set)
{
	if (it_id_set) {
		unsigned long flags;
		spin_lock_irqsave(&idr_lock, flags);
		idr_remove(&posix_timers_id, tmr->it_id);
		spin_unlock_irqrestore(&idr_lock, flags);
	}
	sigqueue_free(tmr->sigq);
	if (unlikely(tmr->it_process) &&
	    tmr->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
		put_task_struct(tmr->it_process);
	kmem_cache_free(posix_timers_cache, tmr);
}

/* Create a POSIX.1b interval timer. */

asmlinkage long
sys_timer_create(clockid_t which_clock,
		 struct sigevent __user *timer_event_spec,
		 timer_t __user * created_timer_id)
{
	int error = 0;
	struct k_itimer *new_timer = NULL;
	int new_timer_id;
	struct task_struct *process = NULL;
	unsigned long flags;
	sigevent_t event;
	int it_id_set = IT_ID_NOT_SET;

	if (invalid_clockid(which_clock))
		return -EINVAL;

	new_timer = alloc_posix_timer();
	if (unlikely(!new_timer))
		return -EAGAIN;

	spin_lock_init(&new_timer->it_lock);
 retry:
	if (unlikely(!idr_pre_get(&posix_timers_id, GFP_KERNEL))) {
		error = -EAGAIN;
		goto out;
	}
	spin_lock_irq(&idr_lock);
	error = idr_get_new(&posix_timers_id,
			    (void *) new_timer,
			    &new_timer_id);
	spin_unlock_irq(&idr_lock);
	if (error == -EAGAIN)
		goto retry;
	else if (error) {
		/*
		 * Wierd looking, but we return EAGAIN if the IDR is
		 * full (proper POSIX return value for this)
		 */
		error = -EAGAIN;
		goto out;
	}

	it_id_set = IT_ID_SET;
	new_timer->it_id = (timer_t) new_timer_id;
	new_timer->it_clock = which_clock;
	new_timer->it_overrun = -1;
	error = CLOCK_DISPATCH(which_clock, timer_create, (new_timer));
	if (error)
		goto out;

	/*
	 * return the timer_id now.  The next step is hard to
	 * back out if there is an error.
	 */
	if (copy_to_user(created_timer_id,
			 &new_timer_id, sizeof (new_timer_id))) {
		error = -EFAULT;
		goto out;
	}
	if (timer_event_spec) {
		if (copy_from_user(&event, timer_event_spec, sizeof (event))) {
			error = -EFAULT;
			goto out;
		}
		new_timer->it_sigev_notify = event.sigev_notify;
		new_timer->it_sigev_signo = event.sigev_signo;
		new_timer->it_sigev_value = event.sigev_value;

		read_lock(&tasklist_lock);
		if ((process = good_sigevent(&event))) {
			/*
			 * We may be setting up this process for another
			 * thread.  It may be exiting.  To catch this
			 * case the we check the PF_EXITING flag.  If
			 * the flag is not set, the siglock will catch
			 * him before it is too late (in exit_itimers).
			 *
			 * The exec case is a bit more invloved but easy
			 * to code.  If the process is in our thread
			 * group (and it must be or we would not allow
			 * it here) and is doing an exec, it will cause
			 * us to be killed.  In this case it will wait
			 * for us to die which means we can finish this
			 * linkage with our last gasp. I.e. no code :)
			 */
			spin_lock_irqsave(&process->sighand->siglock, flags);
			if (!(process->flags & PF_EXITING)) {
				new_timer->it_process = process;
				list_add(&new_timer->list,
					 &process->signal->posix_timers);
				spin_unlock_irqrestore(&process->sighand->siglock, flags);
				if (new_timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
					get_task_struct(process);
			} else {
				spin_unlock_irqrestore(&process->sighand->siglock, flags);
				process = NULL;
			}
		}
		read_unlock(&tasklist_lock);
		if (!process) {
			error = -EINVAL;
			goto out;
		}
	} else {
		new_timer->it_sigev_notify = SIGEV_SIGNAL;
		new_timer->it_sigev_signo = SIGALRM;
		new_timer->it_sigev_value.sival_int = new_timer->it_id;
		process = current->group_leader;
		spin_lock_irqsave(&process->sighand->siglock, flags);
		new_timer->it_process = process;
		list_add(&new_timer->list, &process->signal->posix_timers);
		spin_unlock_irqrestore(&process->sighand->siglock, flags);
	}

 	/*
	 * In the case of the timer belonging to another task, after
	 * the task is unlocked, the timer is owned by the other task
	 * and may cease to exist at any time.  Don't use or modify
	 * new_timer after the unlock call.
	 */

out:
	if (error)
		release_posix_timer(new_timer, it_id_set);

	return error;
}

/*
 * good_timespec
 *
 * This function checks the elements of a timespec structure.
 *
 * Arguments:
 * ts	     : Pointer to the timespec structure to check
 *
 * Return value:
 * If a NULL pointer was passed in, or the tv_nsec field was less than 0
 * or greater than NSEC_PER_SEC, or the tv_sec field was less than 0,
 * this function returns 0. Otherwise it returns 1.
 */
static int good_timespec(const struct timespec *ts)
{
	if ((!ts) || (ts->tv_sec < 0) ||
			((unsigned) ts->tv_nsec >= NSEC_PER_SEC))
		return 0;
	return 1;
}

/*
 * Locking issues: We need to protect the result of the id look up until
 * we get the timer locked down so it is not deleted under us.  The
 * removal is done under the idr spinlock so we use that here to bridge
 * the find to the timer lock.  To avoid a dead lock, the timer id MUST
 * be release with out holding the timer lock.
 */
static struct k_itimer * lock_timer(timer_t timer_id, unsigned long *flags)
{
	struct k_itimer *timr;
	/*
	 * Watch out here.  We do a irqsave on the idr_lock and pass the
	 * flags part over to the timer lock.  Must not let interrupts in
	 * while we are moving the lock.
	 */

	spin_lock_irqsave(&idr_lock, *flags);
	timr = (struct k_itimer *) idr_find(&posix_timers_id, (int) timer_id);
	if (timr) {
		spin_lock(&timr->it_lock);
		spin_unlock(&idr_lock);

		if ((timr->it_id != timer_id) || !(timr->it_process) ||
				timr->it_process->tgid != current->tgid) {
			unlock_timer(timr, *flags);
			timr = NULL;
		}
	} else
		spin_unlock_irqrestore(&idr_lock, *flags);

	return timr;
}

/*
 * Get the time remaining on a POSIX.1b interval timer.  This function
 * is ALWAYS called with spin_lock_irq on the timer, thus it must not
 * mess with irq.
 *
 * We have a couple of messes to clean up here.  First there is the case
 * of a timer that has a requeue pending.  These timers should appear to
 * be in the timer list with an expiry as if we were to requeue them
 * now.
 *
 * The second issue is the SIGEV_NONE timer which may be active but is
 * not really ever put in the timer list (to save system resources).
 * This timer may be expired, and if so, we will do it here.  Otherwise
 * it is the same as a requeue pending timer WRT to what we should
 * report.
 */
static void
common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
{
	unsigned long expires;
	struct now_struct now;

	do
		expires = timr->it.real.timer.expires;
	while ((volatile long) (timr->it.real.timer.expires) != expires);

	posix_get_now(&now);

	if (expires &&
	    ((timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) &&
	    !timr->it.real.incr &&
	    posix_time_before(&timr->it.real.timer, &now))
		timr->it.real.timer.expires = expires = 0;
	if (expires) {
		if (timr->it_requeue_pending & REQUEUE_PENDING ||
		    (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
			posix_bump_timer(timr, now);
			expires = timr->it.real.timer.expires;
		}
		else
			if (!timer_pending(&timr->it.real.timer))
				expires = 0;
		if (expires)
			expires -= now.jiffies;
	}
	jiffies_to_timespec(expires, &cur_setting->it_value);
	jiffies_to_timespec(timr->it.real.incr, &cur_setting->it_interval);

	if (cur_setting->it_value.tv_sec < 0) {
		cur_setting->it_value.tv_nsec = 1;
		cur_setting->it_value.tv_sec = 0;
	}
}

/* Get the time remaining on a POSIX.1b interval timer. */
asmlinkage long
sys_timer_gettime(timer_t timer_id, struct itimerspec __user *setting)
{
	struct k_itimer *timr;
	struct itimerspec cur_setting;
	unsigned long flags;

	timr = lock_timer(timer_id, &flags);
	if (!timr)
		return -EINVAL;

	CLOCK_DISPATCH(timr->it_clock, timer_get, (timr, &cur_setting));

	unlock_timer(timr, flags);

	if (copy_to_user(setting, &cur_setting, sizeof (cur_setting)))
		return -EFAULT;

	return 0;
}
/*
 * Get the number of overruns of a POSIX.1b interval timer.  This is to
 * be the overrun of the timer last delivered.  At the same time we are
 * accumulating overruns on the next timer.  The overrun is frozen when
 * the signal is delivered, either at the notify time (if the info block
 * is not queued) or at the actual delivery time (as we are informed by
 * the call back to do_schedule_next_timer().  So all we need to do is
 * to pick up the frozen overrun.
 */

asmlinkage long
sys_timer_getoverrun(timer_t timer_id)
{
	struct k_itimer *timr;
	int overrun;
	long flags;

	timr = lock_timer(timer_id, &flags);
	if (!timr)
		return -EINVAL;

	overrun = timr->it_overrun_last;
	unlock_timer(timr, flags);

	return overrun;
}
/*
 * Adjust for absolute time
 *
 * If absolute time is given and it is not CLOCK_MONOTONIC, we need to
 * adjust for the offset between the timer clock (CLOCK_MONOTONIC) and
 * what ever clock he is using.
 *
 * If it is relative time, we need to add the current (CLOCK_MONOTONIC)
 * time to it to get the proper time for the timer.
 */
static int adjust_abs_time(struct k_clock *clock, struct timespec *tp, 
			   int abs, u64 *exp, struct timespec *wall_to)
{
	struct timespec now;
	struct timespec oc = *tp;
	u64 jiffies_64_f;
	int rtn =0;

	if (abs) {
		/*
		 * The mask pick up the 4 basic clocks 
		 */
		if (!((clock - &posix_clocks[0]) & ~CLOCKS_MASK)) {
			jiffies_64_f = do_posix_clock_monotonic_gettime_parts(
				&now,  wall_to);
			/*
			 * If we are doing a MONOTONIC clock
			 */
			if((clock - &posix_clocks[0]) & CLOCKS_MONO){
				now.tv_sec += wall_to->tv_sec;
				now.tv_nsec += wall_to->tv_nsec;
			}
		} else {
			/*
			 * Not one of the basic clocks
			 */
			clock->clock_get(clock - posix_clocks, &now);
			jiffies_64_f = get_jiffies_64();
		}
		/*
		 * Take away now to get delta and normalize
		 */
		set_normalized_timespec(&oc, oc.tv_sec - now.tv_sec,
					oc.tv_nsec - now.tv_nsec);
	}else{
		jiffies_64_f = get_jiffies_64();
	}
	/*
	 * Check if the requested time is prior to now (if so set now)
	 */
	if (oc.tv_sec < 0)
		oc.tv_sec = oc.tv_nsec = 0;

	if (oc.tv_sec | oc.tv_nsec)
		set_normalized_timespec(&oc, oc.tv_sec,
					oc.tv_nsec + clock->res);
	tstojiffie(&oc, clock->res, exp);

	/*
	 * Check if the requested time is more than the timer code
	 * can handle (if so we error out but return the value too).
	 */
	if (*exp > ((u64)MAX_JIFFY_OFFSET))
			/*
			 * This is a considered response, not exactly in
			 * line with the standard (in fact it is silent on
			 * possible overflows).  We assume such a large 
			 * value is ALMOST always a programming error and
			 * try not to compound it by setting a really dumb
			 * value.
			 */
			rtn = -EINVAL;
	/*
	 * return the actual jiffies expire time, full 64 bits
	 */
	*exp += jiffies_64_f;
	return rtn;
}

/* Set a POSIX.1b interval timer. */
/* timr->it_lock is taken. */
static inline int
common_timer_set(struct k_itimer *timr, int flags,
		 struct itimerspec *new_setting, struct itimerspec *old_setting)
{
	struct k_clock *clock = &posix_clocks[timr->it_clock];
	u64 expire_64;

	if (old_setting)
		common_timer_get(timr, old_setting);

	/* disable the timer */
	timr->it.real.incr = 0;
	/*
	 * careful here.  If smp we could be in the "fire" routine which will
	 * be spinning as we hold the lock.  But this is ONLY an SMP issue.
	 */
	if (try_to_del_timer_sync(&timr->it.real.timer) < 0) {
#ifdef CONFIG_SMP
		/*
		 * It can only be active if on an other cpu.  Since
		 * we have cleared the interval stuff above, it should
		 * clear once we release the spin lock.  Of course once
		 * we do that anything could happen, including the
		 * complete melt down of the timer.  So return with
		 * a "retry" exit status.
		 */
		return TIMER_RETRY;
#endif
	}

	remove_from_abslist(timr);

	timr->it_requeue_pending = (timr->it_requeue_pending + 2) & 
		~REQUEUE_PENDING;
	timr->it_overrun_last = 0;
	timr->it_overrun = -1;
	/*
	 *switch off the timer when it_value is zero
	 */
	if (!new_setting->it_value.tv_sec && !new_setting->it_value.tv_nsec) {
		timr->it.real.timer.expires = 0;
		return 0;
	}

	if (adjust_abs_time(clock,
			    &new_setting->it_value, flags & TIMER_ABSTIME, 
			    &expire_64, &(timr->it.real.wall_to_prev))) {
		return -EINVAL;
	}
	timr->it.real.timer.expires = (unsigned long)expire_64;
	tstojiffie(&new_setting->it_interval, clock->res, &expire_64);
	timr->it.real.incr = (unsigned long)expire_64;

	/*
	 * We do not even queue SIGEV_NONE timers!  But we do put them
	 * in the abs list so we can do that right.
	 */
	if (((timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE))
		add_timer(&timr->it.real.timer);

	if (flags & TIMER_ABSTIME && clock->abs_struct) {
		spin_lock(&clock->abs_struct->lock);
		list_add_tail(&(timr->it.real.abs_timer_entry),
			      &(clock->abs_struct->list));
		spin_unlock(&clock->abs_struct->lock);
	}
	return 0;
}

/* Set a POSIX.1b interval timer */
asmlinkage long
sys_timer_settime(timer_t timer_id, int flags,
		  const struct itimerspec __user *new_setting,
		  struct itimerspec __user *old_setting)
{
	struct k_itimer *timr;
	struct itimerspec new_spec, old_spec;
	int error = 0;
	long flag;
	struct itimerspec *rtn = old_setting ? &old_spec : NULL;

	if (!new_setting)
		return -EINVAL;

	if (copy_from_user(&new_spec, new_setting, sizeof (new_spec)))
		return -EFAULT;

	if ((!good_timespec(&new_spec.it_interval)) ||
	    (!good_timespec(&new_spec.it_value)))
		return -EINVAL;
retry:
	timr = lock_timer(timer_id, &flag);
	if (!timr)
		return -EINVAL;

	error = CLOCK_DISPATCH(timr->it_clock, timer_set,
			       (timr, flags, &new_spec, rtn));

	unlock_timer(timr, flag);
	if (error == TIMER_RETRY) {
		rtn = NULL;	// We already got the old time...
		goto retry;
	}

	if (old_setting && !error && copy_to_user(old_setting,
						  &old_spec, sizeof (old_spec)))
		error = -EFAULT;

	return error;
}

static inline int common_timer_del(struct k_itimer *timer)
{
	timer->it.real.incr = 0;

	if (try_to_del_timer_sync(&timer->it.real.timer) < 0) {
#ifdef CONFIG_SMP
		/*
		 * It can only be active if on an other cpu.  Since
		 * we have cleared the interval stuff above, it should
		 * clear once we release the spin lock.  Of course once
		 * we do that anything could happen, including the
		 * complete melt down of the timer.  So return with
		 * a "retry" exit status.
		 */
		return TIMER_RETRY;
#endif
	}

	remove_from_abslist(timer);

	return 0;
}

static inline int timer_delete_hook(struct k_itimer *timer)
{
	return CLOCK_DISPATCH(timer->it_clock, timer_del, (timer));
}

/* Delete a POSIX.1b interval timer. */
asmlinkage long
sys_timer_delete(timer_t timer_id)
{
	struct k_itimer *timer;
	long flags;

#ifdef CONFIG_SMP
	int error;
retry_delete:
#endif
	timer = lock_timer(timer_id, &flags);
	if (!timer)
		return -EINVAL;

#ifdef CONFIG_SMP
	error = timer_delete_hook(timer);

	if (error == TIMER_RETRY) {
		unlock_timer(timer, flags);
		goto retry_delete;
	}
#else
	timer_delete_hook(timer);
#endif
	spin_lock(&current->sighand->siglock);
	list_del(&timer->list);
	spin_unlock(&current->sighand->siglock);
	/*
	 * This keeps any tasks waiting on the spin lock from thinking
	 * they got something (see the lock code above).
	 */
	if (timer->it_process) {
		if (timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
			put_task_struct(timer->it_process);
		timer->it_process = NULL;
	}
	unlock_timer(timer, flags);
	release_posix_timer(timer, IT_ID_SET);
	return 0;
}
/*
 * return timer owned by the process, used by exit_itimers
 */
static inline void itimer_delete(struct k_itimer *timer)
{
	unsigned long flags;

#ifdef CONFIG_SMP
	int error;
retry_delete:
#endif
	spin_lock_irqsave(&timer->it_lock, flags);

#ifdef CONFIG_SMP
	error = timer_delete_hook(timer);

	if (error == TIMER_RETRY) {
		unlock_timer(timer, flags);
		goto retry_delete;
	}
#else
	timer_delete_hook(timer);
#endif
	list_del(&timer->list);
	/*
	 * This keeps any tasks waiting on the spin lock from thinking
	 * they got something (see the lock code above).
	 */
	if (timer->it_process) {
		if (timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
			put_task_struct(timer->it_process);
		timer->it_process = NULL;
	}
	unlock_timer(timer, flags);
	release_posix_timer(timer, IT_ID_SET);
}

/*
 * This is called by do_exit or de_thread, only when there are no more
 * references to the shared signal_struct.
 */
void exit_itimers(struct signal_struct *sig)
{
	struct k_itimer *tmr;

	while (!list_empty(&sig->posix_timers)) {
		tmr = list_entry(sig->posix_timers.next, struct k_itimer, list);
		itimer_delete(tmr);
	}
}

/*
 * And now for the "clock" calls
 *
 * These functions are called both from timer functions (with the timer
 * spin_lock_irq() held and from clock calls with no locking.	They must
 * use the save flags versions of locks.
 */

/*
 * We do ticks here to avoid the irq lock ( they take sooo long).
 * The seqlock is great here.  Since we a reader, we don't really care
 * if we are interrupted since we don't take lock that will stall us or
 * any other cpu. Voila, no irq lock is needed.
 *
 */

static u64 do_posix_clock_monotonic_gettime_parts(
	struct timespec *tp, struct timespec *mo)
{
	u64 jiff;
	unsigned int seq;

	do {
		seq = read_seqbegin(&xtime_lock);
		getnstimeofday(tp);
		*mo = wall_to_monotonic;
		jiff = jiffies_64;

	} while(read_seqretry(&xtime_lock, seq));

	return jiff;
}

static int do_posix_clock_monotonic_get(clockid_t clock, struct timespec *tp)
{
	struct timespec wall_to_mono;

	do_posix_clock_monotonic_gettime_parts(tp, &wall_to_mono);

	tp->tv_sec += wall_to_mono.tv_sec;
	tp->tv_nsec += wall_to_mono.tv_nsec;

	if ((tp->tv_nsec - NSEC_PER_SEC) > 0) {
		tp->tv_nsec -= NSEC_PER_SEC;
		tp->tv_sec++;
	}
	return 0;
}

int do_posix_clock_monotonic_gettime(struct timespec *tp)
{
	return do_posix_clock_monotonic_get(CLOCK_MONOTONIC, tp);
}

int do_posix_clock_nosettime(clockid_t clockid, struct timespec *tp)
{
	return -EINVAL;
}
EXPORT_SYMBOL_GPL(do_posix_clock_nosettime);

int do_posix_clock_notimer_create(struct k_itimer *timer)
{
	return -EINVAL;
}
EXPORT_SYMBOL_GPL(do_posix_clock_notimer_create);

int do_posix_clock_nonanosleep(clockid_t clock, int flags, struct timespec *t)
{
#ifndef ENOTSUP
	return -EOPNOTSUPP;	/* aka ENOTSUP in userland for POSIX */
#else  /*  parisc does define it separately.  */
	return -ENOTSUP;
#endif
}
EXPORT_SYMBOL_GPL(do_posix_clock_nonanosleep);

asmlinkage long
sys_clock_settime(clockid_t which_clock, const struct timespec __user *tp)
{
	struct timespec new_tp;

	if (invalid_clockid(which_clock))
		return -EINVAL;
	if (copy_from_user(&new_tp, tp, sizeof (*tp)))
		return -EFAULT;

	return CLOCK_DISPATCH(which_clock, clock_set, (which_clock, &new_tp));
}

asmlinkage long
sys_clock_gettime(clockid_t which_clock, struct timespec __user *tp)
{
	struct timespec kernel_tp;
	int error;

	if (invalid_clockid(which_clock))
		return -EINVAL;
	error = CLOCK_DISPATCH(which_clock, clock_get,
			       (which_clock, &kernel_tp));
	if (!error && copy_to_user(tp, &kernel_tp, sizeof (kernel_tp)))
		error = -EFAULT;

	return error;

}

asmlinkage long
sys_clock_getres(clockid_t which_clock, struct timespec __user *tp)
{
	struct timespec rtn_tp;
	int error;

	if (invalid_clockid(which_clock))
		return -EINVAL;

	error = CLOCK_DISPATCH(which_clock, clock_getres,
			       (which_clock, &rtn_tp));

	if (!error && tp && copy_to_user(tp, &rtn_tp, sizeof (rtn_tp))) {
		error = -EFAULT;
	}

	return error;
}

/*
 * The standard says that an absolute nanosleep call MUST wake up at
 * the requested time in spite of clock settings.  Here is what we do:
 * For each nanosleep call that needs it (only absolute and not on
 * CLOCK_MONOTONIC* (as it can not be set)) we thread a little structure
 * into the "nanosleep_abs_list".  All we need is the task_struct pointer.
 * When ever the clock is set we just wake up all those tasks.	 The rest
 * is done by the while loop in clock_nanosleep().
 *
 * On locking, clock_was_set() is called from update_wall_clock which
 * holds (or has held for it) a write_lock_irq( xtime_lock) and is
 * called from the timer bh code.  Thus we need the irq save locks.
 *
 * Also, on the call from update_wall_clock, that is done as part of a
 * softirq thing.  We don't want to delay the system that much (possibly
 * long list of timers to fix), so we defer that work to keventd.
 */

static DECLARE_WAIT_QUEUE_HEAD(nanosleep_abs_wqueue);
static DECLARE_WORK(clock_was_set_work, (void(*)(void*))clock_was_set, NULL);

static DECLARE_MUTEX(clock_was_set_lock);

void clock_was_set(void)
{
	struct k_itimer *timr;
	struct timespec new_wall_to;
	LIST_HEAD(cws_list);
	unsigned long seq;


	if (unlikely(in_interrupt())) {
		schedule_work(&clock_was_set_work);
		return;
	}
	wake_up_all(&nanosleep_abs_wqueue);

	/*
	 * Check if there exist TIMER_ABSTIME timers to correct.
	 *
	 * Notes on locking: This code is run in task context with irq
	 * on.  We CAN be interrupted!  All other usage of the abs list
	 * lock is under the timer lock which holds the irq lock as
	 * well.  We REALLY don't want to scan the whole list with the
	 * interrupt system off, AND we would like a sequence lock on
	 * this code as well.  Since we assume that the clock will not
	 * be set often, it seems ok to take and release the irq lock
	 * for each timer.  In fact add_timer will do this, so this is
	 * not an issue.  So we know when we are done, we will move the
	 * whole list to a new location.  Then as we process each entry,
	 * we will move it to the actual list again.  This way, when our
	 * copy is empty, we are done.  We are not all that concerned
	 * about preemption so we will use a semaphore lock to protect
	 * aginst reentry.  This way we will not stall another
	 * processor.  It is possible that this may delay some timers
	 * that should have expired, given the new clock, but even this
	 * will be minimal as we will always update to the current time,
	 * even if it was set by a task that is waiting for entry to
	 * this code.  Timers that expire too early will be caught by
	 * the expire code and restarted.

	 * Absolute timers that repeat are left in the abs list while
	 * waiting for the task to pick up the signal.  This means we
	 * may find timers that are not in the "add_timer" list, but are
	 * in the abs list.  We do the same thing for these, save
	 * putting them back in the "add_timer" list.  (Note, these are
	 * left in the abs list mainly to indicate that they are
	 * ABSOLUTE timers, a fact that is used by the re-arm code, and
	 * for which we have no other flag.)

	 */

	down(&clock_was_set_lock);
	spin_lock_irq(&abs_list.lock);
	list_splice_init(&abs_list.list, &cws_list);
	spin_unlock_irq(&abs_list.lock);
	do {
		do {
			seq = read_seqbegin(&xtime_lock);
			new_wall_to =	wall_to_monotonic;
		} while (read_seqretry(&xtime_lock, seq));

		spin_lock_irq(&abs_list.lock);
		if (list_empty(&cws_list)) {
			spin_unlock_irq(&abs_list.lock);
			break;
		}
		timr = list_entry(cws_list.next, struct k_itimer,
				  it.real.abs_timer_entry);

		list_del_init(&timr->it.real.abs_timer_entry);
		if (add_clockset_delta(timr, &new_wall_to) &&
		    del_timer(&timr->it.real.timer))  /* timer run yet? */
			add_timer(&timr->it.real.timer);
		list_add(&timr->it.real.abs_timer_entry, &abs_list.list);
		spin_unlock_irq(&abs_list.lock);
	} while (1);

	up(&clock_was_set_lock);
}

long clock_nanosleep_restart(struct restart_block *restart_block);

asmlinkage long
sys_clock_nanosleep(clockid_t which_clock, int flags,
		    const struct timespec __user *rqtp,
		    struct timespec __user *rmtp)
{
	struct timespec t;
	struct restart_block *restart_block =
	    &(current_thread_info()->restart_block);
	int ret;

	if (invalid_clockid(which_clock))
		return -EINVAL;

	if (copy_from_user(&t, rqtp, sizeof (struct timespec)))
		return -EFAULT;

	if ((unsigned) t.tv_nsec >= NSEC_PER_SEC || t.tv_sec < 0)
		return -EINVAL;

	/*
	 * Do this here as nsleep function does not have the real address.
	 */
	restart_block->arg1 = (unsigned long)rmtp;

	ret = CLOCK_DISPATCH(which_clock, nsleep, (which_clock, flags, &t));

	if ((ret == -ERESTART_RESTARTBLOCK) && rmtp &&
					copy_to_user(rmtp, &t, sizeof (t)))
		return -EFAULT;
	return ret;
}


static int common_nsleep(clockid_t which_clock,
			 int flags, struct timespec *tsave)
{
	struct timespec t, dum;
	DECLARE_WAITQUEUE(abs_wqueue, current);
	u64 rq_time = (u64)0;
	s64 left;
	int abs;
	struct restart_block *restart_block =
	    &current_thread_info()->restart_block;

	abs_wqueue.flags = 0;
	abs = flags & TIMER_ABSTIME;

	if (restart_block->fn == clock_nanosleep_restart) {
		/*
		 * Interrupted by a non-delivered signal, pick up remaining
		 * time and continue.  Remaining time is in arg2 & 3.
		 */
		restart_block->fn = do_no_restart_syscall;

		rq_time = restart_block->arg3;
		rq_time = (rq_time << 32) + restart_block->arg2;
		if (!rq_time)
			return -EINTR;
		left = rq_time - get_jiffies_64();
		if (left <= (s64)0)
			return 0;	/* Already passed */
	}

	if (abs && (posix_clocks[which_clock].clock_get !=
			    posix_clocks[CLOCK_MONOTONIC].clock_get))
		add_wait_queue(&nanosleep_abs_wqueue, &abs_wqueue);

	do {
		t = *tsave;
		if (abs || !rq_time) {
			adjust_abs_time(&posix_clocks[which_clock], &t, abs,
					&rq_time, &dum);
		}

		left = rq_time - get_jiffies_64();
		if (left >= (s64)MAX_JIFFY_OFFSET)
			left = (s64)MAX_JIFFY_OFFSET;
		if (left < (s64)0)
			break;

		schedule_timeout_interruptible(left);

		left = rq_time - get_jiffies_64();
	} while (left > (s64)0 && !test_thread_flag(TIF_SIGPENDING));

	if (abs_wqueue.task_list.next)
		finish_wait(&nanosleep_abs_wqueue, &abs_wqueue);

	if (left > (s64)0) {

		/*
		 * Always restart abs calls from scratch to pick up any
		 * clock shifting that happened while we are away.
		 */
		if (abs)
			return -ERESTARTNOHAND;

		left *= TICK_NSEC;
		tsave->tv_sec = div_long_long_rem(left, 
						  NSEC_PER_SEC, 
						  &tsave->tv_nsec);
		/*
		 * Restart works by saving the time remaing in 
		 * arg2 & 3 (it is 64-bits of jiffies).  The other
		 * info we need is the clock_id (saved in arg0). 
		 * The sys_call interface needs the users 
		 * timespec return address which _it_ saves in arg1.
		 * Since we have cast the nanosleep call to a clock_nanosleep
		 * both can be restarted with the same code.
		 */
		restart_block->fn = clock_nanosleep_restart;
		restart_block->arg0 = which_clock;
		/*
		 * Caller sets arg1
		 */
		restart_block->arg2 = rq_time & 0xffffffffLL;
		restart_block->arg3 = rq_time >> 32;

		return -ERESTART_RESTARTBLOCK;
	}

	return 0;
}
/*
 * This will restart clock_nanosleep.
 */
long
clock_nanosleep_restart(struct restart_block *restart_block)
{
	struct timespec t;
	int ret = common_nsleep(restart_block->arg0, 0, &t);

	if ((ret == -ERESTART_RESTARTBLOCK) && restart_block->arg1 &&
	    copy_to_user((struct timespec __user *)(restart_block->arg1), &t,
			 sizeof (t)))
		return -EFAULT;
	return ret;
}