summaryrefslogtreecommitdiffstats
path: root/arch/ia64/sn/kernel/xpc_channel.c
blob: 8255a9be4632adbc325bc96643208ea1a04b8fa6 (plain)
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
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (c) 2004-2006 Silicon Graphics, Inc.  All Rights Reserved.
 */


/*
 * Cross Partition Communication (XPC) channel support.
 *
 *	This is the part of XPC that manages the channels and
 *	sends/receives messages across them to/from other partitions.
 *
 */


#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/cache.h>
#include <linux/interrupt.h>
#include <linux/mutex.h>
#include <linux/completion.h>
#include <asm/sn/bte.h>
#include <asm/sn/sn_sal.h>
#include <asm/sn/xpc.h>


/*
 * Guarantee that the kzalloc'd memory is cacheline aligned.
 */
static void *
xpc_kzalloc_cacheline_aligned(size_t size, gfp_t flags, void **base)
{
	/* see if kzalloc will give us cachline aligned memory by default */
	*base = kzalloc(size, flags);
	if (*base == NULL) {
		return NULL;
	}
	if ((u64) *base == L1_CACHE_ALIGN((u64) *base)) {
		return *base;
	}
	kfree(*base);

	/* nope, we'll have to do it ourselves */
	*base = kzalloc(size + L1_CACHE_BYTES, flags);
	if (*base == NULL) {
		return NULL;
	}
	return (void *) L1_CACHE_ALIGN((u64) *base);
}


/*
 * Set up the initial values for the XPartition Communication channels.
 */
static void
xpc_initialize_channels(struct xpc_partition *part, partid_t partid)
{
	int ch_number;
	struct xpc_channel *ch;


	for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
		ch = &part->channels[ch_number];

		ch->partid = partid;
		ch->number = ch_number;
		ch->flags = XPC_C_DISCONNECTED;

		ch->local_GP = &part->local_GPs[ch_number];
		ch->local_openclose_args =
					&part->local_openclose_args[ch_number];

		atomic_set(&ch->kthreads_assigned, 0);
		atomic_set(&ch->kthreads_idle, 0);
		atomic_set(&ch->kthreads_active, 0);

		atomic_set(&ch->references, 0);
		atomic_set(&ch->n_to_notify, 0);

		spin_lock_init(&ch->lock);
		mutex_init(&ch->msg_to_pull_mutex);
		init_completion(&ch->wdisconnect_wait);

		atomic_set(&ch->n_on_msg_allocate_wq, 0);
		init_waitqueue_head(&ch->msg_allocate_wq);
		init_waitqueue_head(&ch->idle_wq);
	}
}


/*
 * Setup the infrastructure necessary to support XPartition Communication
 * between the specified remote partition and the local one.
 */
enum xpc_retval
xpc_setup_infrastructure(struct xpc_partition *part)
{
	int ret, cpuid;
	struct timer_list *timer;
	partid_t partid = XPC_PARTID(part);


	/*
	 * Zero out MOST of the entry for this partition. Only the fields
	 * starting with `nchannels' will be zeroed. The preceding fields must
	 * remain `viable' across partition ups and downs, since they may be
	 * referenced during this memset() operation.
	 */
	memset(&part->nchannels, 0, sizeof(struct xpc_partition) -
				offsetof(struct xpc_partition, nchannels));

	/*
	 * Allocate all of the channel structures as a contiguous chunk of
	 * memory.
	 */
	part->channels = kzalloc(sizeof(struct xpc_channel) * XPC_NCHANNELS,
								GFP_KERNEL);
	if (part->channels == NULL) {
		dev_err(xpc_chan, "can't get memory for channels\n");
		return xpcNoMemory;
	}

	part->nchannels = XPC_NCHANNELS;


	/* allocate all the required GET/PUT values */

	part->local_GPs = xpc_kzalloc_cacheline_aligned(XPC_GP_SIZE,
					GFP_KERNEL, &part->local_GPs_base);
	if (part->local_GPs == NULL) {
		kfree(part->channels);
		part->channels = NULL;
		dev_err(xpc_chan, "can't get memory for local get/put "
			"values\n");
		return xpcNoMemory;
	}

	part->remote_GPs = xpc_kzalloc_cacheline_aligned(XPC_GP_SIZE,
					GFP_KERNEL, &part->remote_GPs_base);
	if (part->remote_GPs == NULL) {
		dev_err(xpc_chan, "can't get memory for remote get/put "
			"values\n");
		kfree(part->local_GPs_base);
		part->local_GPs = NULL;
		kfree(part->channels);
		part->channels = NULL;
		return xpcNoMemory;
	}


	/* allocate all the required open and close args */

	part->local_openclose_args = xpc_kzalloc_cacheline_aligned(
					XPC_OPENCLOSE_ARGS_SIZE, GFP_KERNEL,
					&part->local_openclose_args_base);
	if (part->local_openclose_args == NULL) {
		dev_err(xpc_chan, "can't get memory for local connect args\n");
		kfree(part->remote_GPs_base);
		part->remote_GPs = NULL;
		kfree(part->local_GPs_base);
		part->local_GPs = NULL;
		kfree(part->channels);
		part->channels = NULL;
		return xpcNoMemory;
	}

	part->remote_openclose_args = xpc_kzalloc_cacheline_aligned(
					XPC_OPENCLOSE_ARGS_SIZE, GFP_KERNEL,
					&part->remote_openclose_args_base);
	if (part->remote_openclose_args == NULL) {
		dev_err(xpc_chan, "can't get memory for remote connect args\n");
		kfree(part->local_openclose_args_base);
		part->local_openclose_args = NULL;
		kfree(part->remote_GPs_base);
		part->remote_GPs = NULL;
		kfree(part->local_GPs_base);
		part->local_GPs = NULL;
		kfree(part->channels);
		part->channels = NULL;
		return xpcNoMemory;
	}


	xpc_initialize_channels(part, partid);

	atomic_set(&part->nchannels_active, 0);
	atomic_set(&part->nchannels_engaged, 0);


	/* local_IPI_amo were set to 0 by an earlier memset() */

	/* Initialize this partitions AMO_t structure */
	part->local_IPI_amo_va = xpc_IPI_init(partid);

	spin_lock_init(&part->IPI_lock);

	atomic_set(&part->channel_mgr_requests, 1);
	init_waitqueue_head(&part->channel_mgr_wq);

	sprintf(part->IPI_owner, "xpc%02d", partid);
	ret = request_irq(SGI_XPC_NOTIFY, xpc_notify_IRQ_handler, SA_SHIRQ,
				part->IPI_owner, (void *) (u64) partid);
	if (ret != 0) {
		dev_err(xpc_chan, "can't register NOTIFY IRQ handler, "
			"errno=%d\n", -ret);
		kfree(part->remote_openclose_args_base);
		part->remote_openclose_args = NULL;
		kfree(part->local_openclose_args_base);
		part->local_openclose_args = NULL;
		kfree(part->remote_GPs_base);
		part->remote_GPs = NULL;
		kfree(part->local_GPs_base);
		part->local_GPs = NULL;
		kfree(part->channels);
		part->channels = NULL;
		return xpcLackOfResources;
	}

	/* Setup a timer to check for dropped IPIs */
	timer = &part->dropped_IPI_timer;
	init_timer(timer);
	timer->function = (void (*)(unsigned long)) xpc_dropped_IPI_check;
	timer->data = (unsigned long) part;
	timer->expires = jiffies + XPC_P_DROPPED_IPI_WAIT;
	add_timer(timer);

	/*
	 * With the setting of the partition setup_state to XPC_P_SETUP, we're
	 * declaring that this partition is ready to go.
	 */
	part->setup_state = XPC_P_SETUP;


	/*
	 * Setup the per partition specific variables required by the
	 * remote partition to establish channel connections with us.
	 *
	 * The setting of the magic # indicates that these per partition
	 * specific variables are ready to be used.
	 */
	xpc_vars_part[partid].GPs_pa = __pa(part->local_GPs);
	xpc_vars_part[partid].openclose_args_pa =
					__pa(part->local_openclose_args);
	xpc_vars_part[partid].IPI_amo_pa = __pa(part->local_IPI_amo_va);
	cpuid = raw_smp_processor_id();	/* any CPU in this partition will do */
	xpc_vars_part[partid].IPI_nasid = cpuid_to_nasid(cpuid);
	xpc_vars_part[partid].IPI_phys_cpuid = cpu_physical_id(cpuid);
	xpc_vars_part[partid].nchannels = part->nchannels;
	xpc_vars_part[partid].magic = XPC_VP_MAGIC1;

	return xpcSuccess;
}


/*
 * Create a wrapper that hides the underlying mechanism for pulling a cacheline
 * (or multiple cachelines) from a remote partition.
 *
 * src must be a cacheline aligned physical address on the remote partition.
 * dst must be a cacheline aligned virtual address on this partition.
 * cnt must be an cacheline sized
 */
static enum xpc_retval
xpc_pull_remote_cachelines(struct xpc_partition *part, void *dst,
				const void *src, size_t cnt)
{
	bte_result_t bte_ret;


	DBUG_ON((u64) src != L1_CACHE_ALIGN((u64) src));
	DBUG_ON((u64) dst != L1_CACHE_ALIGN((u64) dst));
	DBUG_ON(cnt != L1_CACHE_ALIGN(cnt));

	if (part->act_state == XPC_P_DEACTIVATING) {
		return part->reason;
	}

	bte_ret = xp_bte_copy((u64) src, (u64) ia64_tpa((u64) dst),
				(u64) cnt, (BTE_NORMAL | BTE_WACQUIRE), NULL);
	if (bte_ret == BTE_SUCCESS) {
		return xpcSuccess;
	}

	dev_dbg(xpc_chan, "xp_bte_copy() from partition %d failed, ret=%d\n",
		XPC_PARTID(part), bte_ret);

	return xpc_map_bte_errors(bte_ret);
}


/*
 * Pull the remote per partititon specific variables from the specified
 * partition.
 */
enum xpc_retval
xpc_pull_remote_vars_part(struct xpc_partition *part)
{
	u8 buffer[L1_CACHE_BYTES * 2];
	struct xpc_vars_part *pulled_entry_cacheline =
			(struct xpc_vars_part *) L1_CACHE_ALIGN((u64) buffer);
	struct xpc_vars_part *pulled_entry;
	u64 remote_entry_cacheline_pa, remote_entry_pa;
	partid_t partid = XPC_PARTID(part);
	enum xpc_retval ret;


	/* pull the cacheline that contains the variables we're interested in */

	DBUG_ON(part->remote_vars_part_pa !=
				L1_CACHE_ALIGN(part->remote_vars_part_pa));
	DBUG_ON(sizeof(struct xpc_vars_part) != L1_CACHE_BYTES / 2);

	remote_entry_pa = part->remote_vars_part_pa +
			sn_partition_id * sizeof(struct xpc_vars_part);

	remote_entry_cacheline_pa = (remote_entry_pa & ~(L1_CACHE_BYTES - 1));

	pulled_entry = (struct xpc_vars_part *) ((u64) pulled_entry_cacheline +
				(remote_entry_pa & (L1_CACHE_BYTES - 1)));

	ret = xpc_pull_remote_cachelines(part, pulled_entry_cacheline,
					(void *) remote_entry_cacheline_pa,
					L1_CACHE_BYTES);
	if (ret != xpcSuccess) {
		dev_dbg(xpc_chan, "failed to pull XPC vars_part from "
			"partition %d, ret=%d\n", partid, ret);
		return ret;
	}


	/* see if they've been set up yet */

	if (pulled_entry->magic != XPC_VP_MAGIC1 &&
				pulled_entry->magic != XPC_VP_MAGIC2) {

		if (pulled_entry->magic != 0) {
			dev_dbg(xpc_chan, "partition %d's XPC vars_part for "
				"partition %d has bad magic value (=0x%lx)\n",
				partid, sn_partition_id, pulled_entry->magic);
			return xpcBadMagic;
		}

		/* they've not been initialized yet */
		return xpcRetry;
	}

	if (xpc_vars_part[partid].magic == XPC_VP_MAGIC1) {

		/* validate the variables */

		if (pulled_entry->GPs_pa == 0 ||
				pulled_entry->openclose_args_pa == 0 ||
					pulled_entry->IPI_amo_pa == 0) {

			dev_err(xpc_chan, "partition %d's XPC vars_part for "
				"partition %d are not valid\n", partid,
				sn_partition_id);
			return xpcInvalidAddress;
		}

		/* the variables we imported look to be valid */

		part->remote_GPs_pa = pulled_entry->GPs_pa;
		part->remote_openclose_args_pa =
					pulled_entry->openclose_args_pa;
		part->remote_IPI_amo_va =
				      (AMO_t *) __va(pulled_entry->IPI_amo_pa);
		part->remote_IPI_nasid = pulled_entry->IPI_nasid;
		part->remote_IPI_phys_cpuid = pulled_entry->IPI_phys_cpuid;

		if (part->nchannels > pulled_entry->nchannels) {
			part->nchannels = pulled_entry->nchannels;
		}

		/* let the other side know that we've pulled their variables */

		xpc_vars_part[partid].magic = XPC_VP_MAGIC2;
	}

	if (pulled_entry->magic == XPC_VP_MAGIC1) {
		return xpcRetry;
	}

	return xpcSuccess;
}


/*
 * Get the IPI flags and pull the openclose args and/or remote GPs as needed.
 */
static u64
xpc_get_IPI_flags(struct xpc_partition *part)
{
	unsigned long irq_flags;
	u64 IPI_amo;
	enum xpc_retval ret;


	/*
	 * See if there are any IPI flags to be handled.
	 */

	spin_lock_irqsave(&part->IPI_lock, irq_flags);
	if ((IPI_amo = part->local_IPI_amo) != 0) {
		part->local_IPI_amo = 0;
	}
	spin_unlock_irqrestore(&part->IPI_lock, irq_flags);


	if (XPC_ANY_OPENCLOSE_IPI_FLAGS_SET(IPI_amo)) {
		ret = xpc_pull_remote_cachelines(part,
					part->remote_openclose_args,
					(void *) part->remote_openclose_args_pa,
					XPC_OPENCLOSE_ARGS_SIZE);
		if (ret != xpcSuccess) {
			XPC_DEACTIVATE_PARTITION(part, ret);

			dev_dbg(xpc_chan, "failed to pull openclose args from "
				"partition %d, ret=%d\n", XPC_PARTID(part),
				ret);

			/* don't bother processing IPIs anymore */
			IPI_amo = 0;
		}
	}

	if (XPC_ANY_MSG_IPI_FLAGS_SET(IPI_amo)) {
		ret = xpc_pull_remote_cachelines(part, part->remote_GPs,
						(void *) part->remote_GPs_pa,
						XPC_GP_SIZE);
		if (ret != xpcSuccess) {
			XPC_DEACTIVATE_PARTITION(part, ret);

			dev_dbg(xpc_chan, "failed to pull GPs from partition "
				"%d, ret=%d\n", XPC_PARTID(part), ret);

			/* don't bother processing IPIs anymore */
			IPI_amo = 0;
		}
	}

	return IPI_amo;
}


/*
 * Allocate the local message queue and the notify queue.
 */
static enum xpc_retval
xpc_allocate_local_msgqueue(struct xpc_channel *ch)
{
	unsigned long irq_flags;
	int nentries;
	size_t nbytes;


	// >>> may want to check for ch->flags & XPC_C_DISCONNECTING between
	// >>> iterations of the for-loop, bail if set?

	// >>> should we impose a minumum #of entries? like 4 or 8?
	for (nentries = ch->local_nentries; nentries > 0; nentries--) {

		nbytes = nentries * ch->msg_size;
		ch->local_msgqueue = xpc_kzalloc_cacheline_aligned(nbytes,
						GFP_KERNEL,
						&ch->local_msgqueue_base);
		if (ch->local_msgqueue == NULL) {
			continue;
		}

		nbytes = nentries * sizeof(struct xpc_notify);
		ch->notify_queue = kzalloc(nbytes, GFP_KERNEL);
		if (ch->notify_queue == NULL) {
			kfree(ch->local_msgqueue_base);
			ch->local_msgqueue = NULL;
			continue;
		}

		spin_lock_irqsave(&ch->lock, irq_flags);
		if (nentries < ch->local_nentries) {
			dev_dbg(xpc_chan, "nentries=%d local_nentries=%d, "
				"partid=%d, channel=%d\n", nentries,
				ch->local_nentries, ch->partid, ch->number);

			ch->local_nentries = nentries;
		}
		spin_unlock_irqrestore(&ch->lock, irq_flags);
		return xpcSuccess;
	}

	dev_dbg(xpc_chan, "can't get memory for local message queue and notify "
		"queue, partid=%d, channel=%d\n", ch->partid, ch->number);
	return xpcNoMemory;
}


/*
 * Allocate the cached remote message queue.
 */
static enum xpc_retval
xpc_allocate_remote_msgqueue(struct xpc_channel *ch)
{
	unsigned long irq_flags;
	int nentries;
	size_t nbytes;


	DBUG_ON(ch->remote_nentries <= 0);

	// >>> may want to check for ch->flags & XPC_C_DISCONNECTING between
	// >>> iterations of the for-loop, bail if set?

	// >>> should we impose a minumum #of entries? like 4 or 8?
	for (nentries = ch->remote_nentries; nentries > 0; nentries--) {

		nbytes = nentries * ch->msg_size;
		ch->remote_msgqueue = xpc_kzalloc_cacheline_aligned(nbytes,
						GFP_KERNEL,
						&ch->remote_msgqueue_base);
		if (ch->remote_msgqueue == NULL) {
			continue;
		}

		spin_lock_irqsave(&ch->lock, irq_flags);
		if (nentries < ch->remote_nentries) {
			dev_dbg(xpc_chan, "nentries=%d remote_nentries=%d, "
				"partid=%d, channel=%d\n", nentries,
				ch->remote_nentries, ch->partid, ch->number);

			ch->remote_nentries = nentries;
		}
		spin_unlock_irqrestore(&ch->lock, irq_flags);
		return xpcSuccess;
	}

	dev_dbg(xpc_chan, "can't get memory for cached remote message queue, "
		"partid=%d, channel=%d\n", ch->partid, ch->number);
	return xpcNoMemory;
}


/*
 * Allocate message queues and other stuff associated with a channel.
 *
 * Note: Assumes all of the channel sizes are filled in.
 */
static enum xpc_retval
xpc_allocate_msgqueues(struct xpc_channel *ch)
{
	unsigned long irq_flags;
	enum xpc_retval ret;


	DBUG_ON(ch->flags & XPC_C_SETUP);

	if ((ret = xpc_allocate_local_msgqueue(ch)) != xpcSuccess) {
		return ret;
	}

	if ((ret = xpc_allocate_remote_msgqueue(ch)) != xpcSuccess) {
		kfree(ch->local_msgqueue_base);
		ch->local_msgqueue = NULL;
		kfree(ch->notify_queue);
		ch->notify_queue = NULL;
		return ret;
	}

	spin_lock_irqsave(&ch->lock, irq_flags);
	ch->flags |= XPC_C_SETUP;
	spin_unlock_irqrestore(&ch->lock, irq_flags);

	return xpcSuccess;
}


/*
 * Process a connect message from a remote partition.
 *
 * Note: xpc_process_connect() is expecting to be called with the
 * spin_lock_irqsave held and will leave it locked upon return.
 */
static void
xpc_process_connect(struct xpc_channel *ch, unsigned long *irq_flags)
{
	enum xpc_retval ret;


	DBUG_ON(!spin_is_locked(&ch->lock));

	if (!(ch->flags & XPC_C_OPENREQUEST) ||
				!(ch->flags & XPC_C_ROPENREQUEST)) {
		/* nothing more to do for now */
		return;
	}
	DBUG_ON(!(ch->flags & XPC_C_CONNECTING));

	if (!(ch->flags & XPC_C_SETUP)) {
		spin_unlock_irqrestore(&ch->lock, *irq_flags);
		ret = xpc_allocate_msgqueues(ch);
		spin_lock_irqsave(&ch->lock, *irq_flags);

		if (ret != xpcSuccess) {
			XPC_DISCONNECT_CHANNEL(ch, ret, irq_flags);
		}
		if (ch->flags & (XPC_C_CONNECTED | XPC_C_DISCONNECTING)) {
			return;
		}

		DBUG_ON(!(ch->flags & XPC_C_SETUP));
		DBUG_ON(ch->local_msgqueue == NULL);
		DBUG_ON(ch->remote_msgqueue == NULL);
	}

	if (!(ch->flags & XPC_C_OPENREPLY)) {
		ch->flags |= XPC_C_OPENREPLY;
		xpc_IPI_send_openreply(ch, irq_flags);
	}

	if (!(ch->flags & XPC_C_ROPENREPLY)) {
		return;
	}

	DBUG_ON(ch->remote_msgqueue_pa == 0);

	ch->flags = (XPC_C_CONNECTED | XPC_C_SETUP);	/* clear all else */

	dev_info(xpc_chan, "channel %d to partition %d connected\n",
		ch->number, ch->partid);

	spin_unlock_irqrestore(&ch->lock, *irq_flags);
	xpc_create_kthreads(ch, 1);
	spin_lock_irqsave(&ch->lock, *irq_flags);
}


/*
 * Notify those who wanted to be notified upon delivery of their message.
 */
static void
xpc_notify_senders(struct xpc_channel *ch, enum xpc_retval reason, s64 put)
{
	struct xpc_notify *notify;
	u8 notify_type;
	s64 get = ch->w_remote_GP.get - 1;


	while (++get < put && atomic_read(&ch->n_to_notify) > 0) {

		notify = &ch->notify_queue[get % ch->local_nentries];

		/*
		 * See if the notify entry indicates it was associated with
		 * a message who's sender wants to be notified. It is possible
		 * that it is, but someone else is doing or has done the
		 * notification.
		 */
		notify_type = notify->type;
		if (notify_type == 0 ||
				cmpxchg(&notify->type, notify_type, 0) !=
								notify_type) {
			continue;
		}

		DBUG_ON(notify_type != XPC_N_CALL);

		atomic_dec(&ch->n_to_notify);

		if (notify->func != NULL) {
			dev_dbg(xpc_chan, "notify->func() called, notify=0x%p, "
				"msg_number=%ld, partid=%d, channel=%d\n",
				(void *) notify, get, ch->partid, ch->number);

			notify->func(reason, ch->partid, ch->number,
								notify->key);

			dev_dbg(xpc_chan, "notify->func() returned, "
				"notify=0x%p, msg_number=%ld, partid=%d, "
				"channel=%d\n", (void *) notify, get,
				ch->partid, ch->number);
		}
	}
}


/*
 * Free up message queues and other stuff that were allocated for the specified
 * channel.
 *
 * Note: ch->reason and ch->reason_line are left set for debugging purposes,
 * they're cleared when XPC_C_DISCONNECTED is cleared.
 */
static void
xpc_free_msgqueues(struct xpc_channel *ch)
{
	DBUG_ON(!spin_is_locked(&ch->lock));
	DBUG_ON(atomic_read(&ch->n_to_notify) != 0);

	ch->remote_msgqueue_pa = 0;
	ch->func = NULL;
	ch->key = NULL;
	ch->msg_size = 0;
	ch->local_nentries = 0;
	ch->remote_nentries = 0;
	ch->kthreads_assigned_limit = 0;
	ch->kthreads_idle_limit = 0;

	ch->local_GP->get = 0;
	ch->local_GP->put = 0;
	ch->remote_GP.get = 0;
	ch->remote_GP.put = 0;
	ch->w_local_GP.get = 0;
	ch->w_local_GP.put = 0;
	ch->w_remote_GP.get = 0;
	ch->w_remote_GP.put = 0;
	ch->next_msg_to_pull = 0;

	if (ch->flags & XPC_C_SETUP) {
		ch->flags &= ~XPC_C_SETUP;

		dev_dbg(xpc_chan, "ch->flags=0x%x, partid=%d, channel=%d\n",
			ch->flags, ch->partid, ch->number);

		kfree(ch->local_msgqueue_base);
		ch->local_msgqueue = NULL;
		kfree(ch->remote_msgqueue_base);
		ch->remote_msgqueue = NULL;
		kfree(ch->notify_queue);
		ch->notify_queue = NULL;
	}
}


/*
 * spin_lock_irqsave() is expected to be held on entry.
 */
static void
xpc_process_disconnect(struct xpc_channel *ch, unsigned long *irq_flags)
{
	struct xpc_partition *part = &xpc_partitions[ch->partid];
	u32 channel_was_connected = (ch->flags & XPC_C_WASCONNECTED);


	DBUG_ON(!spin_is_locked(&ch->lock));

	if (!(ch->flags & XPC_C_DISCONNECTING)) {
		return;
	}

	DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));

	/* make sure all activity has settled down first */

	if (atomic_read(&ch->references) > 0 ||
			((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
			!(ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE))) {
		return;
	}
	DBUG_ON(atomic_read(&ch->kthreads_assigned) != 0);

	if (part->act_state == XPC_P_DEACTIVATING) {
		/* can't proceed until the other side disengages from us */
		if (xpc_partition_engaged(1UL << ch->partid)) {
			return;
		}

	} else {

		/* as long as the other side is up do the full protocol */

		if (!(ch->flags & XPC_C_RCLOSEREQUEST)) {
			return;
		}

		if (!(ch->flags & XPC_C_CLOSEREPLY)) {
			ch->flags |= XPC_C_CLOSEREPLY;
			xpc_IPI_send_closereply(ch, irq_flags);
		}

		if (!(ch->flags & XPC_C_RCLOSEREPLY)) {
			return;
		}
	}

	/* wake those waiting for notify completion */
	if (atomic_read(&ch->n_to_notify) > 0) {
		/* >>> we do callout while holding ch->lock */
		xpc_notify_senders(ch, ch->reason, ch->w_local_GP.put);
	}

	/* both sides are disconnected now */

	if (ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE) {
		spin_unlock_irqrestore(&ch->lock, *irq_flags);
		xpc_disconnect_callout(ch, xpcDisconnected);
		spin_lock_irqsave(&ch->lock, *irq_flags);
	}

	/* it's now safe to free the channel's message queues */
	xpc_free_msgqueues(ch);

	/* mark disconnected, clear all other flags except XPC_C_WDISCONNECT */
	ch->flags = (XPC_C_DISCONNECTED | (ch->flags & XPC_C_WDISCONNECT));

	atomic_dec(&part->nchannels_active);

	if (channel_was_connected) {
		dev_info(xpc_chan, "channel %d to partition %d disconnected, "
			"reason=%d\n", ch->number, ch->partid, ch->reason);
	}

	if (ch->flags & XPC_C_WDISCONNECT) {
		/* we won't lose the CPU since we're holding ch->lock */
		complete(&ch->wdisconnect_wait);
	} else if (ch->delayed_IPI_flags) {
		if (part->act_state != XPC_P_DEACTIVATING) {
			/* time to take action on any delayed IPI flags */
			spin_lock(&part->IPI_lock);
			XPC_SET_IPI_FLAGS(part->local_IPI_amo, ch->number,
							ch->delayed_IPI_flags);
			spin_unlock(&part->IPI_lock);
		}
		ch->delayed_IPI_flags = 0;
	}
}


/*
 * Process a change in the channel's remote connection state.
 */
static void
xpc_process_openclose_IPI(struct xpc_partition *part, int ch_number,
				u8 IPI_flags)
{
	unsigned long irq_flags;
	struct xpc_openclose_args *args =
				&part->remote_openclose_args[ch_number];
	struct xpc_channel *ch = &part->channels[ch_number];
	enum xpc_retval reason;



	spin_lock_irqsave(&ch->lock, irq_flags);

again:

	if ((ch->flags & XPC_C_DISCONNECTED) &&
					(ch->flags & XPC_C_WDISCONNECT)) {
		/*
		 * Delay processing IPI flags until thread waiting disconnect
		 * has had a chance to see that the channel is disconnected.
		 */
		ch->delayed_IPI_flags |= IPI_flags;
		spin_unlock_irqrestore(&ch->lock, irq_flags);
		return;
	}


	if (IPI_flags & XPC_IPI_CLOSEREQUEST) {

		dev_dbg(xpc_chan, "XPC_IPI_CLOSEREQUEST (reason=%d) received "
			"from partid=%d, channel=%d\n", args->reason,
			ch->partid, ch->number);

		/*
		 * If RCLOSEREQUEST is set, we're probably waiting for
		 * RCLOSEREPLY. We should find it and a ROPENREQUEST packed
		 * with this RCLOSEREQUEST in the IPI_flags.
		 */

		if (ch->flags & XPC_C_RCLOSEREQUEST) {
			DBUG_ON(!(ch->flags & XPC_C_DISCONNECTING));
			DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
			DBUG_ON(!(ch->flags & XPC_C_CLOSEREPLY));
			DBUG_ON(ch->flags & XPC_C_RCLOSEREPLY);

			DBUG_ON(!(IPI_flags & XPC_IPI_CLOSEREPLY));
			IPI_flags &= ~XPC_IPI_CLOSEREPLY;
			ch->flags |= XPC_C_RCLOSEREPLY;

			/* both sides have finished disconnecting */
			xpc_process_disconnect(ch, &irq_flags);
			DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
			goto again;
		}

		if (ch->flags & XPC_C_DISCONNECTED) {
			if (!(IPI_flags & XPC_IPI_OPENREQUEST)) {
				if ((XPC_GET_IPI_FLAGS(part->local_IPI_amo,
					 ch_number) & XPC_IPI_OPENREQUEST)) {

					DBUG_ON(ch->delayed_IPI_flags != 0);
					spin_lock(&part->IPI_lock);
					XPC_SET_IPI_FLAGS(part->local_IPI_amo,
							ch_number,
							XPC_IPI_CLOSEREQUEST);
					spin_unlock(&part->IPI_lock);
				}
				spin_unlock_irqrestore(&ch->lock, irq_flags);
				return;
			}

			XPC_SET_REASON(ch, 0, 0);
			ch->flags &= ~XPC_C_DISCONNECTED;

			atomic_inc(&part->nchannels_active);
			ch->flags |= (XPC_C_CONNECTING | XPC_C_ROPENREQUEST);
		}

		IPI_flags &= ~(XPC_IPI_OPENREQUEST | XPC_IPI_OPENREPLY);

		/*
		 * The meaningful CLOSEREQUEST connection state fields are:
		 *      reason = reason connection is to be closed
		 */

		ch->flags |= XPC_C_RCLOSEREQUEST;

		if (!(ch->flags & XPC_C_DISCONNECTING)) {
			reason = args->reason;
			if (reason <= xpcSuccess || reason > xpcUnknownReason) {
				reason = xpcUnknownReason;
			} else if (reason == xpcUnregistering) {
				reason = xpcOtherUnregistering;
			}

			XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);

			DBUG_ON(IPI_flags & XPC_IPI_CLOSEREPLY);
			spin_unlock_irqrestore(&ch->lock, irq_flags);
			return;
		}

		xpc_process_disconnect(ch, &irq_flags);
	}


	if (IPI_flags & XPC_IPI_CLOSEREPLY) {

		dev_dbg(xpc_chan, "XPC_IPI_CLOSEREPLY received from partid=%d,"
			" channel=%d\n", ch->partid, ch->number);

		if (ch->flags & XPC_C_DISCONNECTED) {
			DBUG_ON(part->act_state != XPC_P_DEACTIVATING);
			spin_unlock_irqrestore(&ch->lock, irq_flags);
			return;
		}

		DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));

		if (!(ch->flags & XPC_C_RCLOSEREQUEST)) {
			if ((XPC_GET_IPI_FLAGS(part->local_IPI_amo, ch_number)
						& XPC_IPI_CLOSEREQUEST)) {

				DBUG_ON(ch->delayed_IPI_flags != 0);
				spin_lock(&part->IPI_lock);
				XPC_SET_IPI_FLAGS(part->local_IPI_amo,
						ch_number, XPC_IPI_CLOSEREPLY);
				spin_unlock(&part->IPI_lock);
			}
			spin_unlock_irqrestore(&ch->lock, irq_flags);
			return;
		}

		ch->flags |= XPC_C_RCLOSEREPLY;

		if (ch->flags & XPC_C_CLOSEREPLY) {
			/* both sides have finished disconnecting */
			xpc_process_disconnect(ch, &irq_flags);
		}
	}


	if (IPI_flags & XPC_IPI_OPENREQUEST) {

		dev_dbg(xpc_chan, "XPC_IPI_OPENREQUEST (msg_size=%d, "
			"local_nentries=%d) received from partid=%d, "
			"channel=%d\n", args->msg_size, args->local_nentries,
			ch->partid, ch->number);

		if (part->act_state == XPC_P_DEACTIVATING ||
					(ch->flags & XPC_C_ROPENREQUEST)) {
			spin_unlock_irqrestore(&ch->lock, irq_flags);
			return;
		}

		if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_WDISCONNECT)) {
			ch->delayed_IPI_flags |= XPC_IPI_OPENREQUEST;
			spin_unlock_irqrestore(&ch->lock, irq_flags);
			return;
		}
		DBUG_ON(!(ch->flags & (XPC_C_DISCONNECTED |
							XPC_C_OPENREQUEST)));
		DBUG_ON(ch->flags & (XPC_C_ROPENREQUEST | XPC_C_ROPENREPLY |
					XPC_C_OPENREPLY | XPC_C_CONNECTED));

		/*
		 * The meaningful OPENREQUEST connection state fields are:
		 *      msg_size = size of channel's messages in bytes
		 *      local_nentries = remote partition's local_nentries
		 */
		if (args->msg_size == 0 || args->local_nentries == 0) {
			/* assume OPENREQUEST was delayed by mistake */
			spin_unlock_irqrestore(&ch->lock, irq_flags);
			return;
		}

		ch->flags |= (XPC_C_ROPENREQUEST | XPC_C_CONNECTING);
		ch->remote_nentries = args->local_nentries;


		if (ch->flags & XPC_C_OPENREQUEST) {
			if (args->msg_size != ch->msg_size) {
				XPC_DISCONNECT_CHANNEL(ch, xpcUnequalMsgSizes,
								&irq_flags);
				spin_unlock_irqrestore(&ch->lock, irq_flags);
				return;
			}
		} else {
			ch->msg_size = args->msg_size;

			XPC_SET_REASON(ch, 0, 0);
			ch->flags &= ~XPC_C_DISCONNECTED;

			atomic_inc(&part->nchannels_active);
		}

		xpc_process_connect(ch, &irq_flags);
	}


	if (IPI_flags & XPC_IPI_OPENREPLY) {

		dev_dbg(xpc_chan, "XPC_IPI_OPENREPLY (local_msgqueue_pa=0x%lx, "
			"local_nentries=%d, remote_nentries=%d) received from "
			"partid=%d, channel=%d\n", args->local_msgqueue_pa,
			args->local_nentries, args->remote_nentries,
			ch->partid, ch->number);

		if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED)) {
			spin_unlock_irqrestore(&ch->lock, irq_flags);
			return;
		}
		if (!(ch->flags & XPC_C_OPENREQUEST)) {
			XPC_DISCONNECT_CHANNEL(ch, xpcOpenCloseError,
								&irq_flags);
			spin_unlock_irqrestore(&ch->lock, irq_flags);
			return;
		}

		DBUG_ON(!(ch->flags & XPC_C_ROPENREQUEST));
		DBUG_ON(ch->flags & XPC_C_CONNECTED);

		/*
		 * The meaningful OPENREPLY connection state fields are:
		 *      local_msgqueue_pa = physical address of remote
		 *			    partition's local_msgqueue
		 *      local_nentries = remote partition's local_nentries
		 *      remote_nentries = remote partition's remote_nentries
		 */
		DBUG_ON(args->local_msgqueue_pa == 0);
		DBUG_ON(args->local_nentries == 0);
		DBUG_ON(args->remote_nentries == 0);

		ch->flags |= XPC_C_ROPENREPLY;
		ch->remote_msgqueue_pa = args->local_msgqueue_pa;

		if (args->local_nentries < ch->remote_nentries) {
			dev_dbg(xpc_chan, "XPC_IPI_OPENREPLY: new "
				"remote_nentries=%d, old remote_nentries=%d, "
				"partid=%d, channel=%d\n",
				args->local_nentries, ch->remote_nentries,
				ch->partid, ch->number);

			ch->remote_nentries = args->local_nentries;
		}
		if (args->remote_nentries < ch->local_nentries) {
			dev_dbg(xpc_chan, "XPC_IPI_OPENREPLY: new "
				"local_nentries=%d, old local_nentries=%d, "
				"partid=%d, channel=%d\n",
				args->remote_nentries, ch->local_nentries,
				ch->partid, ch->number);

			ch->local_nentries = args->remote_nentries;
		}

		xpc_process_connect(ch, &irq_flags);
	}

	spin_unlock_irqrestore(&ch->lock, irq_flags);
}


/*
 * Attempt to establish a channel connection to a remote partition.
 */
static enum xpc_retval
xpc_connect_channel(struct xpc_channel *ch)
{
	unsigned long irq_flags;
	struct xpc_registration *registration = &xpc_registrations[ch->number];


	if (mutex_trylock(&registration->mutex) == 0) {
		return xpcRetry;
	}

	if (!XPC_CHANNEL_REGISTERED(ch->number)) {
		mutex_unlock(&registration->mutex);
		return xpcUnregistered;
	}

	spin_lock_irqsave(&ch->lock, irq_flags);

	DBUG_ON(ch->flags & XPC_C_CONNECTED);
	DBUG_ON(ch->flags & XPC_C_OPENREQUEST);

	if (ch->flags & XPC_C_DISCONNECTING) {
		spin_unlock_irqrestore(&ch->lock, irq_flags);
		mutex_unlock(&registration->mutex);
		return ch->reason;
	}


	/* add info from the channel connect registration to the channel */

	ch->kthreads_assigned_limit = registration->assigned_limit;
	ch->kthreads_idle_limit = registration->idle_limit;
	DBUG_ON(atomic_read(&ch->kthreads_assigned) != 0);
	DBUG_ON(atomic_read(&ch->kthreads_idle) != 0);
	DBUG_ON(atomic_read(&ch->kthreads_active) != 0);

	ch->func = registration->func;
	DBUG_ON(registration->func == NULL);
	ch->key = registration->key;

	ch->local_nentries = registration->nentries;

	if (ch->flags & XPC_C_ROPENREQUEST) {
		if (registration->msg_size != ch->msg_size) {
			/* the local and remote sides aren't the same */

			/*
			 * Because XPC_DISCONNECT_CHANNEL() can block we're
			 * forced to up the registration sema before we unlock
			 * the channel lock. But that's okay here because we're
			 * done with the part that required the registration
			 * sema. XPC_DISCONNECT_CHANNEL() requires that the
			 * channel lock be locked and will unlock and relock
			 * the channel lock as needed.
			 */
			mutex_unlock(&registration->mutex);
			XPC_DISCONNECT_CHANNEL(ch, xpcUnequalMsgSizes,
								&irq_flags);
			spin_unlock_irqrestore(&ch->lock, irq_flags);
			return xpcUnequalMsgSizes;
		}
	} else {
		ch->msg_size = registration->msg_size;

		XPC_SET_REASON(ch, 0, 0);
		ch->flags &= ~XPC_C_DISCONNECTED;

		atomic_inc(&xpc_partitions[ch->partid].nchannels_active);
	}

	mutex_unlock(&registration->mutex);


	/* initiate the connection */

	ch->flags |= (XPC_C_OPENREQUEST | XPC_C_CONNECTING);
	xpc_IPI_send_openrequest(ch, &irq_flags);

	xpc_process_connect(ch, &irq_flags);

	spin_unlock_irqrestore(&ch->lock, irq_flags);

	return xpcSuccess;
}


/*
 * Clear some of the msg flags in the local message queue.
 */
static inline void
xpc_clear_local_msgqueue_flags(struct xpc_channel *ch)
{
	struct xpc_msg *msg;
	s64 get;


	get = ch->w_remote_GP.get;
	do {
		msg = (struct xpc_msg *) ((u64) ch->local_msgqueue +
				(get % ch->local_nentries) * ch->msg_size);
		msg->flags = 0;
	} while (++get < (volatile s64) ch->remote_GP.get);
}


/*
 * Clear some of the msg flags in the remote message queue.
 */
static inline void
xpc_clear_remote_msgqueue_flags(struct xpc_channel *ch)
{
	struct xpc_msg *msg;
	s64 put;


	put = ch->w_remote_GP.put;
	do {
		msg = (struct xpc_msg *) ((u64) ch->remote_msgqueue +
				(put % ch->remote_nentries) * ch->msg_size);
		msg->flags = 0;
	} while (++put < (volatile s64) ch->remote_GP.put);
}


static void
xpc_process_msg_IPI(struct xpc_partition *part, int ch_number)
{
	struct xpc_channel *ch = &part->channels[ch_number];
	int nmsgs_sent;


	ch->remote_GP = part->remote_GPs[ch_number];


	/* See what, if anything, has changed for each connected channel */

	xpc_msgqueue_ref(ch);

	if (ch->w_remote_GP.get == ch->remote_GP.get &&
				ch->w_remote_GP.put == ch->remote_GP.put) {
		/* nothing changed since GPs were last pulled */
		xpc_msgqueue_deref(ch);
		return;
	}

	if (!(ch->flags & XPC_C_CONNECTED)){
		xpc_msgqueue_deref(ch);
		return;
	}


	/*
	 * First check to see if messages recently sent by us have been
	 * received by the other side. (The remote GET value will have
	 * changed since we last looked at it.)
	 */

	if (ch->w_remote_GP.get != ch->remote_GP.get) {

		/*
		 * We need to notify any senders that want to be notified
		 * that their sent messages have been received by their
		 * intended recipients. We need to do this before updating
		 * w_remote_GP.get so that we don't allocate the same message
		 * queue entries prematurely (see xpc_allocate_msg()).
		 */
		if (atomic_read(&ch->n_to_notify) > 0) {
			/*
			 * Notify senders that messages sent have been
			 * received and delivered by the other side.
			 */
			xpc_notify_senders(ch, xpcMsgDelivered,
							ch->remote_GP.get);
		}

		/*
		 * Clear msg->flags in previously sent messages, so that
		 * they're ready for xpc_allocate_msg().
		 */
		xpc_clear_local_msgqueue_flags(ch);

		ch->w_remote_GP.get = ch->remote_GP.get;

		dev_dbg(xpc_chan, "w_remote_GP.get changed to %ld, partid=%d, "
			"channel=%d\n", ch->w_remote_GP.get, ch->partid,
			ch->number);

		/*
		 * If anyone was waiting for message queue entries to become
		 * available, wake them up.
		 */
		if (atomic_read(&ch->n_on_msg_allocate_wq) > 0) {
			wake_up(&ch->msg_allocate_wq);
		}
	}


	/*
	 * Now check for newly sent messages by the other side. (The remote
	 * PUT value will have changed since we last looked at it.)
	 */

	if (ch->w_remote_GP.put != ch->remote_GP.put) {
		/*
		 * Clear msg->flags in previously received messages, so that
		 * they're ready for xpc_get_deliverable_msg().
		 */
		xpc_clear_remote_msgqueue_flags(ch);

		ch->w_remote_GP.put = ch->remote_GP.put;

		dev_dbg(xpc_chan, "w_remote_GP.put changed to %ld, partid=%d, "
			"channel=%d\n", ch->w_remote_GP.put, ch->partid,
			ch->number);

		nmsgs_sent = ch->w_remote_GP.put - ch->w_local_GP.get;
		if (nmsgs_sent > 0) {
			dev_dbg(xpc_chan, "msgs waiting to be copied and "
				"delivered=%d, partid=%d, channel=%d\n",
				nmsgs_sent, ch->partid, ch->number);

			if (ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) {
				xpc_activate_kthreads(ch, nmsgs_sent);
			}
		}
	}

	xpc_msgqueue_deref(ch);
}


void
xpc_process_channel_activity(struct xpc_partition *part)
{
	unsigned long irq_flags;
	u64 IPI_amo, IPI_flags;
	struct xpc_channel *ch;
	int ch_number;
	u32 ch_flags;


	IPI_amo = xpc_get_IPI_flags(part);

	/*
	 * Initiate channel connections for registered channels.
	 *
	 * For each connected channel that has pending messages activate idle
	 * kthreads and/or create new kthreads as needed.
	 */

	for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
		ch = &part->channels[ch_number];


		/*
		 * Process any open or close related IPI flags, and then deal
		 * with connecting or disconnecting the channel as required.
		 */

		IPI_flags = XPC_GET_IPI_FLAGS(IPI_amo, ch_number);

		if (XPC_ANY_OPENCLOSE_IPI_FLAGS_SET(IPI_flags)) {
			xpc_process_openclose_IPI(part, ch_number, IPI_flags);
		}

		ch_flags = ch->flags;	/* need an atomic snapshot of flags */

		if (ch_flags & XPC_C_DISCONNECTING) {
			spin_lock_irqsave(&ch->lock, irq_flags);
			xpc_process_disconnect(ch, &irq_flags);
			spin_unlock_irqrestore(&ch->lock, irq_flags);
			continue;
		}

		if (part->act_state == XPC_P_DEACTIVATING) {
			continue;
		}

		if (!(ch_flags & XPC_C_CONNECTED)) {
			if (!(ch_flags & XPC_C_OPENREQUEST)) {
				DBUG_ON(ch_flags & XPC_C_SETUP);
				(void) xpc_connect_channel(ch);
			} else {
				spin_lock_irqsave(&ch->lock, irq_flags);
				xpc_process_connect(ch, &irq_flags);
				spin_unlock_irqrestore(&ch->lock, irq_flags);
			}
			continue;
		}


		/*
		 * Process any message related IPI flags, this may involve the
		 * activation of kthreads to deliver any pending messages sent
		 * from the other partition.
		 */

		if (XPC_ANY_MSG_IPI_FLAGS_SET(IPI_flags)) {
			xpc_process_msg_IPI(part, ch_number);
		}
	}
}


/*
 * XPC's heartbeat code calls this function to inform XPC that a partition is
 * going down.  XPC responds by tearing down the XPartition Communication
 * infrastructure used for the just downed partition.
 *
 * XPC's heartbeat code will never call this function and xpc_partition_up()
 * at the same time. Nor will it ever make multiple calls to either function
 * at the same time.
 */
void
xpc_partition_going_down(struct xpc_partition *part, enum xpc_retval reason)
{
	unsigned long irq_flags;
	int ch_number;
	struct xpc_channel *ch;


	dev_dbg(xpc_chan, "deactivating partition %d, reason=%d\n",
		XPC_PARTID(part), reason);

	if (!xpc_part_ref(part)) {
		/* infrastructure for this partition isn't currently set up */
		return;
	}


	/* disconnect channels associated with the partition going down */

	for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
		ch = &part->channels[ch_number];

		xpc_msgqueue_ref(ch);
		spin_lock_irqsave(&ch->lock, irq_flags);

		XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);

		spin_unlock_irqrestore(&ch->lock, irq_flags);
		xpc_msgqueue_deref(ch);
	}

	xpc_wakeup_channel_mgr(part);

	xpc_part_deref(part);
}


/*
 * Teardown the infrastructure necessary to support XPartition Communication
 * between the specified remote partition and the local one.
 */
void
xpc_teardown_infrastructure(struct xpc_partition *part)
{
	partid_t partid = XPC_PARTID(part);


	/*
	 * We start off by making this partition inaccessible to local
	 * processes by marking it as no longer setup. Then we make it
	 * inaccessible to remote processes by clearing the XPC per partition
	 * specific variable's magic # (which indicates that these variables
	 * are no longer valid) and by ignoring all XPC notify IPIs sent to
	 * this partition.
	 */

	DBUG_ON(atomic_read(&part->nchannels_engaged) != 0);
	DBUG_ON(atomic_read(&part->nchannels_active) != 0);
	DBUG_ON(part->setup_state != XPC_P_SETUP);
	part->setup_state = XPC_P_WTEARDOWN;

	xpc_vars_part[partid].magic = 0;


	free_irq(SGI_XPC_NOTIFY, (void *) (u64) partid);


	/*
	 * Before proceding with the teardown we have to wait until all
	 * existing references cease.
	 */
	wait_event(part->teardown_wq, (atomic_read(&part->references) == 0));


	/* now we can begin tearing down the infrastructure */

	part->setup_state = XPC_P_TORNDOWN;

	/* in case we've still got outstanding timers registered... */
	del_timer_sync(&part->dropped_IPI_timer);

	kfree(part->remote_openclose_args_base);
	part->remote_openclose_args = NULL;
	kfree(part->local_openclose_args_base);
	part->local_openclose_args = NULL;
	kfree(part->remote_GPs_base);
	part->remote_GPs = NULL;
	kfree(part->local_GPs_base);
	part->local_GPs = NULL;
	kfree(part->channels);
	part->channels = NULL;
	part->local_IPI_amo_va = NULL;
}


/*
 * Called by XP at the time of channel connection registration to cause
 * XPC to establish connections to all currently active partitions.
 */
void
xpc_initiate_connect(int ch_number)
{
	partid_t partid;
	struct xpc_partition *part;
	struct xpc_channel *ch;


	DBUG_ON(ch_number < 0 || ch_number >= XPC_NCHANNELS);

	for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
		part = &xpc_partitions[partid];

		if (xpc_part_ref(part)) {
			ch = &part->channels[ch_number];

			/*
			 * Initiate the establishment of a connection on the
			 * newly registered channel to the remote partition.
			 */
			xpc_wakeup_channel_mgr(part);
			xpc_part_deref(part);
		}
	}
}


void
xpc_connected_callout(struct xpc_channel *ch)
{
	/* let the registerer know that a connection has been established */

	if (ch->func != NULL) {
		dev_dbg(xpc_chan, "ch->func() called, reason=xpcConnected, "
			"partid=%d, channel=%d\n", ch->partid, ch->number);

		ch->func(xpcConnected, ch->partid, ch->number,
				(void *) (u64) ch->local_nentries, ch->key);

		dev_dbg(xpc_chan, "ch->func() returned, reason=xpcConnected, "
			"partid=%d, channel=%d\n", ch->partid, ch->number);
	}
}


/*
 * Called by XP at the time of channel connection unregistration to cause
 * XPC to teardown all current connections for the specified channel.
 *
 * Before returning xpc_initiate_disconnect() will wait until all connections
 * on the specified channel have been closed/torndown. So the caller can be
 * assured that they will not be receiving any more callouts from XPC to the
 * function they registered via xpc_connect().
 *
 * Arguments:
 *
 *	ch_number - channel # to unregister.
 */
void
xpc_initiate_disconnect(int ch_number)
{
	unsigned long irq_flags;
	partid_t partid;
	struct xpc_partition *part;
	struct xpc_channel *ch;


	DBUG_ON(ch_number < 0 || ch_number >= XPC_NCHANNELS);

	/* initiate the channel disconnect for every active partition */
	for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
		part = &xpc_partitions[partid];

		if (xpc_part_ref(part)) {
			ch = &part->channels[ch_number];
			xpc_msgqueue_ref(ch);

			spin_lock_irqsave(&ch->lock, irq_flags);

			if (!(ch->flags & XPC_C_DISCONNECTED)) {
				ch->flags |= XPC_C_WDISCONNECT;

				XPC_DISCONNECT_CHANNEL(ch, xpcUnregistering,
								&irq_flags);
			}

			spin_unlock_irqrestore(&ch->lock, irq_flags);

			xpc_msgqueue_deref(ch);
			xpc_part_deref(part);
		}
	}

	xpc_disconnect_wait(ch_number);
}


/*
 * To disconnect a channel, and reflect it back to all who may be waiting.
 *
 * An OPEN is not allowed until XPC_C_DISCONNECTING is cleared by
 * xpc_process_disconnect(), and if set, XPC_C_WDISCONNECT is cleared by
 * xpc_disconnect_wait().
 *
 * THE CHANNEL IS TO BE LOCKED BY THE CALLER AND WILL REMAIN LOCKED UPON RETURN.
 */
void
xpc_disconnect_channel(const int line, struct xpc_channel *ch,
			enum xpc_retval reason, unsigned long *irq_flags)
{
	u32 channel_was_connected = (ch->flags & XPC_C_CONNECTED);


	DBUG_ON(!spin_is_locked(&ch->lock));

	if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED)) {
		return;
	}
	DBUG_ON(!(ch->flags & (XPC_C_CONNECTING | XPC_C_CONNECTED)));

	dev_dbg(xpc_chan, "reason=%d, line=%d, partid=%d, channel=%d\n",
		reason, line, ch->partid, ch->number);

	XPC_SET_REASON(ch, reason, line);

	ch->flags |= (XPC_C_CLOSEREQUEST | XPC_C_DISCONNECTING);
	/* some of these may not have been set */
	ch->flags &= ~(XPC_C_OPENREQUEST | XPC_C_OPENREPLY |
			XPC_C_ROPENREQUEST | XPC_C_ROPENREPLY |
			XPC_C_CONNECTING | XPC_C_CONNECTED);

	xpc_IPI_send_closerequest(ch, irq_flags);

	if (channel_was_connected) {
		ch->flags |= XPC_C_WASCONNECTED;
	}

	spin_unlock_irqrestore(&ch->lock, *irq_flags);

	/* wake all idle kthreads so they can exit */
	if (atomic_read(&ch->kthreads_idle) > 0) {
		wake_up_all(&ch->idle_wq);
	}

	/* wake those waiting to allocate an entry from the local msg queue */
	if (atomic_read(&ch->n_on_msg_allocate_wq) > 0) {
		wake_up(&ch->msg_allocate_wq);
	}

	spin_lock_irqsave(&ch->lock, *irq_flags);
}


void
xpc_disconnect_callout(struct xpc_channel *ch, enum xpc_retval reason)
{
	/*
	 * Let the channel's registerer know that the channel is being
	 * disconnected. We don't want to do this if the registerer was never
	 * informed of a connection being made.
	 */

	if (ch->func != NULL) {
		dev_dbg(xpc_chan, "ch->func() called, reason=%d, partid=%d, "
			"channel=%d\n", reason, ch->partid, ch->number);

		ch->func(reason, ch->partid, ch->number, NULL, ch->key);

		dev_dbg(xpc_chan, "ch->func() returned, reason=%d, partid=%d, "
			"channel=%d\n", reason, ch->partid, ch->number);
	}
}


/*
 * Wait for a message entry to become available for the specified channel,
 * but don't wait any longer than 1 jiffy.
 */
static enum xpc_retval
xpc_allocate_msg_wait(struct xpc_channel *ch)
{
	enum xpc_retval ret;


	if (ch->flags & XPC_C_DISCONNECTING) {
		DBUG_ON(ch->reason == xpcInterrupted);  // >>> Is this true?
		return ch->reason;
	}

	atomic_inc(&ch->n_on_msg_allocate_wq);
	ret = interruptible_sleep_on_timeout(&ch->msg_allocate_wq, 1);
	atomic_dec(&ch->n_on_msg_allocate_wq);

	if (ch->flags & XPC_C_DISCONNECTING) {
		ret = ch->reason;
		DBUG_ON(ch->reason == xpcInterrupted);  // >>> Is this true?
	} else if (ret == 0) {
		ret = xpcTimeout;
	} else {
		ret = xpcInterrupted;
	}

	return ret;
}


/*
 * Allocate an entry for a message from the message queue associated with the
 * specified channel.
 */
static enum xpc_retval
xpc_allocate_msg(struct xpc_channel *ch, u32 flags,
			struct xpc_msg **address_of_msg)
{
	struct xpc_msg *msg;
	enum xpc_retval ret;
	s64 put;


	/* this reference will be dropped in xpc_send_msg() */
	xpc_msgqueue_ref(ch);

	if (ch->flags & XPC_C_DISCONNECTING) {
		xpc_msgqueue_deref(ch);
		return ch->reason;
	}
	if (!(ch->flags & XPC_C_CONNECTED)) {
		xpc_msgqueue_deref(ch);
		return xpcNotConnected;
	}


	/*
	 * Get the next available message entry from the local message queue.
	 * If none are available, we'll make sure that we grab the latest
	 * GP values.
	 */
	ret = xpcTimeout;

	while (1) {

		put = (volatile s64) ch->w_local_GP.put;
		if (put - (volatile s64) ch->w_remote_GP.get <
							ch->local_nentries) {

			/* There are available message entries. We need to try
			 * to secure one for ourselves. We'll do this by trying
			 * to increment w_local_GP.put as long as someone else
			 * doesn't beat us to it. If they do, we'll have to
			 * try again.
		 	 */
			if (cmpxchg(&ch->w_local_GP.put, put, put + 1) ==
									put) {
				/* we got the entry referenced by put */
				break;
			}
			continue;	/* try again */
		}


		/*
		 * There aren't any available msg entries at this time.
		 *
		 * In waiting for a message entry to become available,
		 * we set a timeout in case the other side is not
		 * sending completion IPIs. This lets us fake an IPI
		 * that will cause the IPI handler to fetch the latest
		 * GP values as if an IPI was sent by the other side.
		 */
		if (ret == xpcTimeout) {
			xpc_IPI_send_local_msgrequest(ch);
		}

		if (flags & XPC_NOWAIT) {
			xpc_msgqueue_deref(ch);
			return xpcNoWait;
		}

		ret = xpc_allocate_msg_wait(ch);
		if (ret != xpcInterrupted && ret != xpcTimeout) {
			xpc_msgqueue_deref(ch);
			return ret;
		}
	}


	/* get the message's address and initialize it */
	msg = (struct xpc_msg *) ((u64) ch->local_msgqueue +
				(put % ch->local_nentries) * ch->msg_size);


	DBUG_ON(msg->flags != 0);
	msg->number = put;

	dev_dbg(xpc_chan, "w_local_GP.put changed to %ld; msg=0x%p, "
		"msg_number=%ld, partid=%d, channel=%d\n", put + 1,
		(void *) msg, msg->number, ch->partid, ch->number);

	*address_of_msg = msg;

	return xpcSuccess;
}


/*
 * Allocate an entry for a message from the message queue associated with the
 * specified channel. NOTE that this routine can sleep waiting for a message
 * entry to become available. To not sleep, pass in the XPC_NOWAIT flag.
 *
 * Arguments:
 *
 *	partid - ID of partition to which the channel is connected.
 *	ch_number - channel #.
 *	flags - see xpc.h for valid flags.
 *	payload - address of the allocated payload area pointer (filled in on
 * 	          return) in which the user-defined message is constructed.
 */
enum xpc_retval
xpc_initiate_allocate(partid_t partid, int ch_number, u32 flags, void **payload)
{
	struct xpc_partition *part = &xpc_partitions[partid];
	enum xpc_retval ret = xpcUnknownReason;
	struct xpc_msg *msg = NULL;


	DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
	DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);

	*payload = NULL;

	if (xpc_part_ref(part)) {
		ret = xpc_allocate_msg(&part->channels[ch_number], flags, &msg);
		xpc_part_deref(part);

		if (msg != NULL) {
			*payload = &msg->payload;
		}
	}

	return ret;
}


/*
 * Now we actually send the messages that are ready to be sent by advancing
 * the local message queue's Put value and then send an IPI to the recipient
 * partition.
 */
static void
xpc_send_msgs(struct xpc_channel *ch, s64 initial_put)
{
	struct xpc_msg *msg;
	s64 put = initial_put + 1;
	int send_IPI = 0;


	while (1) {

		while (1) {
			if (put == (volatile s64) ch->w_local_GP.put) {
				break;
			}

			msg = (struct xpc_msg *) ((u64) ch->local_msgqueue +
			       (put % ch->local_nentries) * ch->msg_size);

			if (!(msg->flags & XPC_M_READY)) {
				break;
			}

			put++;
		}

		if (put == initial_put) {
			/* nothing's changed */
			break;
		}

		if (cmpxchg_rel(&ch->local_GP->put, initial_put, put) !=
								initial_put) {
			/* someone else beat us to it */
			DBUG_ON((volatile s64) ch->local_GP->put < initial_put);
			break;
		}

		/* we just set the new value of local_GP->put */

		dev_dbg(xpc_chan, "local_GP->put changed to %ld, partid=%d, "
			"channel=%d\n", put, ch->partid, ch->number);

		send_IPI = 1;

		/*
		 * We need to ensure that the message referenced by
		 * local_GP->put is not XPC_M_READY or that local_GP->put
		 * equals w_local_GP.put, so we'll go have a look.
		 */
		initial_put = put;
	}

	if (send_IPI) {
		xpc_IPI_send_msgrequest(ch);
	}
}


/*
 * Common code that does the actual sending of the message by advancing the
 * local message queue's Put value and sends an IPI to the partition the
 * message is being sent to.
 */
static enum xpc_retval
xpc_send_msg(struct xpc_channel *ch, struct xpc_msg *msg, u8 notify_type,
			xpc_notify_func func, void *key)
{
	enum xpc_retval ret = xpcSuccess;
	struct xpc_notify *notify = notify;
	s64 put, msg_number = msg->number;


	DBUG_ON(notify_type == XPC_N_CALL && func == NULL);
	DBUG_ON((((u64) msg - (u64) ch->local_msgqueue) / ch->msg_size) !=
					msg_number % ch->local_nentries);
	DBUG_ON(msg->flags & XPC_M_READY);

	if (ch->flags & XPC_C_DISCONNECTING) {
		/* drop the reference grabbed in xpc_allocate_msg() */
		xpc_msgqueue_deref(ch);
		return ch->reason;
	}

	if (notify_type != 0) {
		/*
		 * Tell the remote side to send an ACK interrupt when the
		 * message has been delivered.
		 */
		msg->flags |= XPC_M_INTERRUPT;

		atomic_inc(&ch->n_to_notify);

		notify = &ch->notify_queue[msg_number % ch->local_nentries];
		notify->func = func;
		notify->key = key;
		notify->type = notify_type;

		// >>> is a mb() needed here?

		if (ch->flags & XPC_C_DISCONNECTING) {
			/*
			 * An error occurred between our last error check and
			 * this one. We will try to clear the type field from
			 * the notify entry. If we succeed then
			 * xpc_disconnect_channel() didn't already process
			 * the notify entry.
			 */
			if (cmpxchg(&notify->type, notify_type, 0) ==
								notify_type) {
				atomic_dec(&ch->n_to_notify);
				ret = ch->reason;
			}

			/* drop the reference grabbed in xpc_allocate_msg() */
			xpc_msgqueue_deref(ch);
			return ret;
		}
	}

	msg->flags |= XPC_M_READY;

	/*
	 * The preceding store of msg->flags must occur before the following
	 * load of ch->local_GP->put.
	 */
	mb();

	/* see if the message is next in line to be sent, if so send it */

	put = ch->local_GP->put;
	if (put == msg_number) {
		xpc_send_msgs(ch, put);
	}

	/* drop the reference grabbed in xpc_allocate_msg() */
	xpc_msgqueue_deref(ch);
	return ret;
}


/*
 * Send a message previously allocated using xpc_initiate_allocate() on the
 * specified channel connected to the specified partition.
 *
 * This routine will not wait for the message to be received, nor will
 * notification be given when it does happen. Once this routine has returned
 * the message entry allocated via xpc_initiate_allocate() is no longer
 * accessable to the caller.
 *
 * This routine, although called by users, does not call xpc_part_ref() to
 * ensure that the partition infrastructure is in place. It relies on the
 * fact that we called xpc_msgqueue_ref() in xpc_allocate_msg().
 *
 * Arguments:
 *
 *	partid - ID of partition to which the channel is connected.
 *	ch_number - channel # to send message on.
 *	payload - pointer to the payload area allocated via
 *			xpc_initiate_allocate().
 */
enum xpc_retval
xpc_initiate_send(partid_t partid, int ch_number, void *payload)
{
	struct xpc_partition *part = &xpc_partitions[partid];
	struct xpc_msg *msg = XPC_MSG_ADDRESS(payload);
	enum xpc_retval ret;


	dev_dbg(xpc_chan, "msg=0x%p, partid=%d, channel=%d\n", (void *) msg,
		partid, ch_number);

	DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
	DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
	DBUG_ON(msg == NULL);

	ret = xpc_send_msg(&part->channels[ch_number], msg, 0, NULL, NULL);

	return ret;
}


/*
 * Send a message previously allocated using xpc_initiate_allocate on the
 * specified channel connected to the specified partition.
 *
 * This routine will not wait for the message to be sent. Once this routine
 * has returned the message entry allocated via xpc_initiate_allocate() is no
 * longer accessable to the caller.
 *
 * Once the remote end of the channel has received the message, the function
 * passed as an argument to xpc_initiate_send_notify() will be called. This
 * allows the sender to free up or re-use any buffers referenced by the
 * message, but does NOT mean the message has been processed at the remote
 * end by a receiver.
 *
 * If this routine returns an error, the caller's function will NOT be called.
 *
 * This routine, although called by users, does not call xpc_part_ref() to
 * ensure that the partition infrastructure is in place. It relies on the
 * fact that we called xpc_msgqueue_ref() in xpc_allocate_msg().
 *
 * Arguments:
 *
 *	partid - ID of partition to which the channel is connected.
 *	ch_number - channel # to send message on.
 *	payload - pointer to the payload area allocated via
 *			xpc_initiate_allocate().
 *	func - function to call with asynchronous notification of message
 *		  receipt. THIS FUNCTION MUST BE NON-BLOCKING.
 *	key - user-defined key to be passed to the function when it's called.
 */
enum xpc_retval
xpc_initiate_send_notify(partid_t partid, int ch_number, void *payload,
				xpc_notify_func func, void *key)
{
	struct xpc_partition *part = &xpc_partitions[partid];
	struct xpc_msg *msg = XPC_MSG_ADDRESS(payload);
	enum xpc_retval ret;


	dev_dbg(xpc_chan, "msg=0x%p, partid=%d, channel=%d\n", (void *) msg,
		partid, ch_number);

	DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
	DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
	DBUG_ON(msg == NULL);
	DBUG_ON(func == NULL);

	ret = xpc_send_msg(&part->channels[ch_number], msg, XPC_N_CALL,
								func, key);
	return ret;
}


static struct xpc_msg *
xpc_pull_remote_msg(struct xpc_channel *ch, s64 get)
{
	struct xpc_partition *part = &xpc_partitions[ch->partid];
	struct xpc_msg *remote_msg, *msg;
	u32 msg_index, nmsgs;
	u64 msg_offset;
	enum xpc_retval ret;


	if (mutex_lock_interruptible(&ch->msg_to_pull_mutex) != 0) {
		/* we were interrupted by a signal */
		return NULL;
	}

	while (get >= ch->next_msg_to_pull) {

		/* pull as many messages as are ready and able to be pulled */

		msg_index = ch->next_msg_to_pull % ch->remote_nentries;

		DBUG_ON(ch->next_msg_to_pull >=
					(volatile s64) ch->w_remote_GP.put);
		nmsgs =  (volatile s64) ch->w_remote_GP.put -
						ch->next_msg_to_pull;
		if (msg_index + nmsgs > ch->remote_nentries) {
			/* ignore the ones that wrap the msg queue for now */
			nmsgs = ch->remote_nentries - msg_index;
		}

		msg_offset = msg_index * ch->msg_size;
		msg = (struct xpc_msg *) ((u64) ch->remote_msgqueue +
								msg_offset);
		remote_msg = (struct xpc_msg *) (ch->remote_msgqueue_pa +
								msg_offset);

		if ((ret = xpc_pull_remote_cachelines(part, msg, remote_msg,
				nmsgs * ch->msg_size)) != xpcSuccess) {

			dev_dbg(xpc_chan, "failed to pull %d msgs starting with"
				" msg %ld from partition %d, channel=%d, "
				"ret=%d\n", nmsgs, ch->next_msg_to_pull,
				ch->partid, ch->number, ret);

			XPC_DEACTIVATE_PARTITION(part, ret);

			mutex_unlock(&ch->msg_to_pull_mutex);
			return NULL;
		}

		mb();	/* >>> this may not be needed, we're not sure */

		ch->next_msg_to_pull += nmsgs;
	}

	mutex_unlock(&ch->msg_to_pull_mutex);

	/* return the message we were looking for */
	msg_offset = (get % ch->remote_nentries) * ch->msg_size;
	msg = (struct xpc_msg *) ((u64) ch->remote_msgqueue + msg_offset);

	return msg;
}


/*
 * Get a message to be delivered.
 */
static struct xpc_msg *
xpc_get_deliverable_msg(struct xpc_channel *ch)
{
	struct xpc_msg *msg = NULL;
	s64 get;


	do {
		if ((volatile u32) ch->flags & XPC_C_DISCONNECTING) {
			break;
		}

		get = (volatile s64) ch->w_local_GP.get;
		if (get == (volatile s64) ch->w_remote_GP.put) {
			break;
		}

		/* There are messages waiting to be pulled and delivered.
		 * We need to try to secure one for ourselves. We'll do this
		 * by trying to increment w_local_GP.get and hope that no one
		 * else beats us to it. If they do, we'll we'll simply have
		 * to try again for the next one.
	 	 */

		if (cmpxchg(&ch->w_local_GP.get, get, get + 1) == get) {
			/* we got the entry referenced by get */

			dev_dbg(xpc_chan, "w_local_GP.get changed to %ld, "
				"partid=%d, channel=%d\n", get + 1,
				ch->partid, ch->number);

			/* pull the message from the remote partition */

			msg = xpc_pull_remote_msg(ch, get);

			DBUG_ON(msg != NULL && msg->number != get);
			DBUG_ON(msg != NULL && (msg->flags & XPC_M_DONE));
			DBUG_ON(msg != NULL && !(msg->flags & XPC_M_READY));

			break;
		}

	} while (1);

	return msg;
}


/*
 * Deliver a message to its intended recipient.
 */
void
xpc_deliver_msg(struct xpc_channel *ch)
{
	struct xpc_msg *msg;


	if ((msg = xpc_get_deliverable_msg(ch)) != NULL) {

		/*
		 * This ref is taken to protect the payload itself from being
		 * freed before the user is finished with it, which the user
		 * indicates by calling xpc_initiate_received().
		 */
		xpc_msgqueue_ref(ch);

		atomic_inc(&ch->kthreads_active);

		if (ch->func != NULL) {
			dev_dbg(xpc_chan, "ch->func() called, msg=0x%p, "
				"msg_number=%ld, partid=%d, channel=%d\n",
				(void *) msg, msg->number, ch->partid,
				ch->number);

			/* deliver the message to its intended recipient */
			ch->func(xpcMsgReceived, ch->partid, ch->number,
					&msg->payload, ch->key);

			dev_dbg(xpc_chan, "ch->func() returned, msg=0x%p, "
				"msg_number=%ld, partid=%d, channel=%d\n",
				(void *) msg, msg->number, ch->partid,
				ch->number);
		}

		atomic_dec(&ch->kthreads_active);
	}
}


/*
 * Now we actually acknowledge the messages that have been delivered and ack'd
 * by advancing the cached remote message queue's Get value and if requested
 * send an IPI to the message sender's partition.
 */
static void
xpc_acknowledge_msgs(struct xpc_channel *ch, s64 initial_get, u8 msg_flags)
{
	struct xpc_msg *msg;
	s64 get = initial_get + 1;
	int send_IPI = 0;


	while (1) {

		while (1) {
			if (get == (volatile s64) ch->w_local_GP.get) {
				break;
			}

			msg = (struct xpc_msg *) ((u64) ch->remote_msgqueue +
			       (get % ch->remote_nentries) * ch->msg_size);

			if (!(msg->flags & XPC_M_DONE)) {
				break;
			}

			msg_flags |= msg->flags;
			get++;
		}

		if (get == initial_get) {
			/* nothing's changed */
			break;
		}

		if (cmpxchg_rel(&ch->local_GP->get, initial_get, get) !=
								initial_get) {
			/* someone else beat us to it */
			DBUG_ON((volatile s64) ch->local_GP->get <=
								initial_get);
			break;
		}

		/* we just set the new value of local_GP->get */

		dev_dbg(xpc_chan, "local_GP->get changed to %ld, partid=%d, "
			"channel=%d\n", get, ch->partid, ch->number);

		send_IPI = (msg_flags & XPC_M_INTERRUPT);

		/*
		 * We need to ensure that the message referenced by
		 * local_GP->get is not XPC_M_DONE or that local_GP->get
		 * equals w_local_GP.get, so we'll go have a look.
		 */
		initial_get = get;
	}

	if (send_IPI) {
		xpc_IPI_send_msgrequest(ch);
	}
}


/*
 * Acknowledge receipt of a delivered message.
 *
 * If a message has XPC_M_INTERRUPT set, send an interrupt to the partition
 * that sent the message.
 *
 * This function, although called by users, does not call xpc_part_ref() to
 * ensure that the partition infrastructure is in place. It relies on the
 * fact that we called xpc_msgqueue_ref() in xpc_deliver_msg().
 *
 * Arguments:
 *
 *	partid - ID of partition to which the channel is connected.
 *	ch_number - channel # message received on.
 *	payload - pointer to the payload area allocated via
 *			xpc_initiate_allocate().
 */
void
xpc_initiate_received(partid_t partid, int ch_number, void *payload)
{
	struct xpc_partition *part = &xpc_partitions[partid];
	struct xpc_channel *ch;
	struct xpc_msg *msg = XPC_MSG_ADDRESS(payload);
	s64 get, msg_number = msg->number;


	DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
	DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);

	ch = &part->channels[ch_number];

	dev_dbg(xpc_chan, "msg=0x%p, msg_number=%ld, partid=%d, channel=%d\n",
		(void *) msg, msg_number, ch->partid, ch->number);

	DBUG_ON((((u64) msg - (u64) ch->remote_msgqueue) / ch->msg_size) !=
					msg_number % ch->remote_nentries);
	DBUG_ON(msg->flags & XPC_M_DONE);

	msg->flags |= XPC_M_DONE;

	/*
	 * The preceding store of msg->flags must occur before the following
	 * load of ch->local_GP->get.
	 */
	mb();

	/*
	 * See if this message is next in line to be acknowledged as having
	 * been delivered.
	 */
	get = ch->local_GP->get;
	if (get == msg_number) {
		xpc_acknowledge_msgs(ch, get, msg->flags);
	}

	/* the call to xpc_msgqueue_ref() was done by xpc_deliver_msg()  */
	xpc_msgqueue_deref(ch);
}

OpenPOWER on IntegriCloud