/
subr_devsw.c
1699 lines (1460 loc) · 39 KB
/
subr_devsw.c
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
/* $NetBSD: subr_devsw.c,v 1.51 2023/02/15 13:12:45 riastradh Exp $ */
/*-
* Copyright (c) 2001, 2002, 2007, 2008 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by MAEKAWA Masahide <gehenna@NetBSD.org>, and by Andrew Doran.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Overview
*
* subr_devsw.c: registers device drivers by name and by major
* number, and provides wrapper methods for performing I/O and
* other tasks on device drivers, keying on the device number
* (dev_t).
*
* When the system is built, the config(8) command generates
* static tables of device drivers built into the kernel image
* along with their associated methods. These are recorded in
* the cdevsw0 and bdevsw0 tables. Drivers can also be added to
* and removed from the system dynamically.
*
* Allocation
*
* When the system initially boots only the statically allocated
* indexes (bdevsw0, cdevsw0) are used. If these overflow due to
* allocation, we allocate a fixed block of memory to hold the new,
* expanded index. This "fork" of the table is only ever performed
* once in order to guarantee that other threads may safely access
* the device tables:
*
* o Once a thread has a "reference" to the table via an earlier
* open() call, we know that the entry in the table must exist
* and so it is safe to access it.
*
* o Regardless of whether other threads see the old or new
* pointers, they will point to a correct device switch
* structure for the operation being performed.
*
* XXX Currently, the wrapper methods such as cdev_read() verify
* that a device driver does in fact exist before calling the
* associated driver method. This should be changed so that
* once the device is has been referenced by a vnode (opened),
* calling the other methods should be valid until that reference
* is dropped.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: subr_devsw.c,v 1.51 2023/02/15 13:12:45 riastradh Exp $");
#ifdef _KERNEL_OPT
#include "opt_dtrace.h"
#endif
#include <sys/param.h>
#include <sys/conf.h>
#include <sys/kmem.h>
#include <sys/systm.h>
#include <sys/poll.h>
#include <sys/tty.h>
#include <sys/cpu.h>
#include <sys/buf.h>
#include <sys/reboot.h>
#include <sys/sdt.h>
#include <sys/atomic.h>
#include <sys/localcount.h>
#include <sys/pserialize.h>
#include <sys/xcall.h>
#include <sys/device.h>
#ifdef DEVSW_DEBUG
#define DPRINTF(x) printf x
#else /* DEVSW_DEBUG */
#define DPRINTF(x)
#endif /* DEVSW_DEBUG */
#define MAXDEVSW 512 /* the maximum of major device number */
#define BDEVSW_SIZE (sizeof(struct bdevsw *))
#define CDEVSW_SIZE (sizeof(struct cdevsw *))
#define DEVSWCONV_SIZE (sizeof(struct devsw_conv))
struct devswref {
struct localcount *dr_lc;
};
/* XXX bdevsw, cdevsw, max_bdevsws, and max_cdevsws should be volatile */
extern const struct bdevsw **bdevsw, *bdevsw0[];
extern const struct cdevsw **cdevsw, *cdevsw0[];
extern struct devsw_conv *devsw_conv, devsw_conv0[];
extern const int sys_bdevsws, sys_cdevsws;
extern int max_bdevsws, max_cdevsws, max_devsw_convs;
static struct devswref *cdevswref;
static struct devswref *bdevswref;
static kcondvar_t devsw_cv;
static int bdevsw_attach(const struct bdevsw *, devmajor_t *);
static int cdevsw_attach(const struct cdevsw *, devmajor_t *);
static void devsw_detach_locked(const struct bdevsw *, const struct cdevsw *);
kmutex_t device_lock;
void (*biodone_vfs)(buf_t *) = (void *)nullop;
/*
* bdev probes
*/
SDT_PROBE_DEFINE6(sdt, bdev, open, acquire,
"struct bdevsw *"/*bdevsw*/,
"dev_t"/*dev*/,
"int"/*flag*/,
"int"/*devtype*/,
"int"/*unit*/,
"device_t"/*dv*/);
SDT_PROBE_DEFINE4(sdt, bdev, open, entry,
"struct bdevsw *"/*bdevsw*/,
"dev_t"/*dev*/,
"int"/*flag*/,
"int"/*devtype*/);
SDT_PROBE_DEFINE5(sdt, bdev, open, return,
"struct bdevsw *"/*bdevsw*/,
"dev_t"/*dev*/,
"int"/*flag*/,
"int"/*devtype*/,
"int"/*error*/);
SDT_PROBE_DEFINE6(sdt, bdev, open, release,
"struct bdevsw *"/*bdevsw*/,
"dev_t"/*dev*/,
"int"/*flag*/,
"int"/*devtype*/,
"int"/*unit*/,
"device_t"/*dv*/);
SDT_PROBE_DEFINE4(sdt, bdev, cancel, entry,
"struct bdevsw *"/*bdevsw*/,
"dev_t"/*dev*/,
"int"/*flag*/,
"int"/*devtype*/);
SDT_PROBE_DEFINE5(sdt, bdev, cancel, return,
"struct bdevsw *"/*bdevsw*/,
"dev_t"/*dev*/,
"int"/*flag*/,
"int"/*devtype*/,
"int"/*error*/);
SDT_PROBE_DEFINE4(sdt, bdev, close, entry,
"struct bdevsw *"/*bdevsw*/,
"dev_t"/*dev*/,
"int"/*flag*/,
"int"/*devtype*/);
SDT_PROBE_DEFINE5(sdt, bdev, close, return,
"struct bdevsw *"/*bdevsw*/,
"dev_t"/*dev*/,
"int"/*flag*/,
"int"/*devtype*/,
"int"/*error*/);
SDT_PROBE_DEFINE3(sdt, bdev, strategy, entry,
"struct bdevsw *"/*bdevsw*/,
"dev_t"/*dev*/,
"struct buf *"/*bp*/);
SDT_PROBE_DEFINE3(sdt, bdev, strategy, return,
"struct bdevsw *"/*bdevsw*/,
"dev_t"/*dev*/,
"struct buf *"/*bp*/);
SDT_PROBE_DEFINE5(sdt, bdev, ioctl, entry,
"struct bdevsw *"/*bdevsw*/,
"dev_t"/*dev*/,
"unsigned long"/*cmd*/,
"void *"/*data*/,
"int"/*flag*/);
SDT_PROBE_DEFINE6(sdt, bdev, ioctl, return,
"struct bdevsw *"/*bdevsw*/,
"dev_t"/*dev*/,
"unsigned long"/*cmd*/,
"void *"/*data*/,
"int"/*flag*/,
"int"/*error*/);
SDT_PROBE_DEFINE2(sdt, bdev, psize, entry,
"struct bdevsw *"/*bdevsw*/,
"dev_t"/*dev*/);
SDT_PROBE_DEFINE3(sdt, bdev, psize, return,
"struct bdevsw *"/*bdevsw*/,
"dev_t"/*dev*/,
"int"/*psize*/);
SDT_PROBE_DEFINE4(sdt, bdev, discard, entry,
"struct bdevsw *"/*bdevsw*/,
"dev_t"/*dev*/,
"off_t"/*pos*/,
"off_t"/*len*/);
SDT_PROBE_DEFINE5(sdt, bdev, discard, return,
"struct bdevsw *"/*bdevsw*/,
"dev_t"/*dev*/,
"off_t"/*pos*/,
"off_t"/*len*/,
"int"/*error*/);
/*
* cdev probes
*/
SDT_PROBE_DEFINE6(sdt, cdev, open, acquire,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"int"/*flag*/,
"int"/*devtype*/,
"int"/*unit*/,
"device_t"/*dv*/);
SDT_PROBE_DEFINE4(sdt, cdev, open, entry,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"int"/*flag*/,
"int"/*devtype*/);
SDT_PROBE_DEFINE5(sdt, cdev, open, return,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"int"/*flag*/,
"int"/*devtype*/,
"int"/*error*/);
SDT_PROBE_DEFINE6(sdt, cdev, open, release,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"int"/*flag*/,
"int"/*devtype*/,
"int"/*unit*/,
"device_t"/*dv*/);
SDT_PROBE_DEFINE4(sdt, cdev, cancel, entry,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"int"/*flag*/,
"int"/*devtype*/);
SDT_PROBE_DEFINE5(sdt, cdev, cancel, return,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"int"/*flag*/,
"int"/*devtype*/,
"int"/*error*/);
SDT_PROBE_DEFINE4(sdt, cdev, close, entry,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"int"/*flag*/,
"int"/*devtype*/);
SDT_PROBE_DEFINE5(sdt, cdev, close, return,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"int"/*flag*/,
"int"/*devtype*/,
"int"/*error*/);
SDT_PROBE_DEFINE4(sdt, cdev, read, entry,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"struct uio *"/*uio*/,
"int"/*flag*/);
SDT_PROBE_DEFINE5(sdt, cdev, read, return,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"struct uio *"/*uio*/,
"int"/*flag*/,
"int"/*error*/);
SDT_PROBE_DEFINE4(sdt, cdev, write, entry,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"struct uio *"/*uio*/,
"int"/*flag*/);
SDT_PROBE_DEFINE5(sdt, cdev, write, return,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"struct uio *"/*uio*/,
"int"/*flag*/,
"int"/*error*/);
SDT_PROBE_DEFINE5(sdt, cdev, ioctl, entry,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"unsigned long"/*cmd*/,
"void *"/*data*/,
"int"/*flag*/);
SDT_PROBE_DEFINE6(sdt, cdev, ioctl, return,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"unsigned long"/*cmd*/,
"void *"/*data*/,
"int"/*flag*/,
"int"/*error*/);
SDT_PROBE_DEFINE4(sdt, cdev, stop, entry,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"struct tty *"/*tp*/,
"int"/*flag*/);
SDT_PROBE_DEFINE4(sdt, cdev, stop, return,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"struct tty *"/*tp*/,
"int"/*flag*/);
SDT_PROBE_DEFINE3(sdt, cdev, poll, entry,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"int"/*events*/);
SDT_PROBE_DEFINE4(sdt, cdev, poll, return,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"int"/*events*/,
"int"/*revents*/);
SDT_PROBE_DEFINE4(sdt, cdev, mmap, entry,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"off_t"/*off*/,
"int"/*flag*/);
SDT_PROBE_DEFINE5(sdt, cdev, mmap, return,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"off_t"/*off*/,
"int"/*flag*/,
"paddr_t"/*mmapcookie*/);
SDT_PROBE_DEFINE3(sdt, cdev, kqfilter, entry,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"struct knote *"/*kn*/);
SDT_PROBE_DEFINE4(sdt, cdev, kqfilter, return,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"struct knote *"/*kn*/,
"int"/*error*/);
SDT_PROBE_DEFINE4(sdt, cdev, discard, entry,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"off_t"/*pos*/,
"off_t"/*len*/);
SDT_PROBE_DEFINE5(sdt, cdev, discard, return,
"struct cdevsw *"/*cdevsw*/,
"dev_t"/*dev*/,
"off_t"/*pos*/,
"off_t"/*len*/,
"int"/*error*/);
void
devsw_init(void)
{
KASSERT(sys_bdevsws < MAXDEVSW - 1);
KASSERT(sys_cdevsws < MAXDEVSW - 1);
mutex_init(&device_lock, MUTEX_DEFAULT, IPL_NONE);
cv_init(&devsw_cv, "devsw");
}
int
devsw_attach(const char *devname,
const struct bdevsw *bdev, devmajor_t *bmajor,
const struct cdevsw *cdev, devmajor_t *cmajor)
{
struct devsw_conv *conv;
char *name;
int error, i;
if (devname == NULL || cdev == NULL)
return EINVAL;
mutex_enter(&device_lock);
for (i = 0; i < max_devsw_convs; i++) {
conv = &devsw_conv[i];
if (conv->d_name == NULL || strcmp(devname, conv->d_name) != 0)
continue;
if ((bdev != NULL) && (*bmajor < 0))
*bmajor = conv->d_bmajor;
if (*cmajor < 0)
*cmajor = conv->d_cmajor;
if (*bmajor != conv->d_bmajor || *cmajor != conv->d_cmajor) {
error = EINVAL;
goto out;
}
if ((*bmajor >= 0 && bdev == NULL) || *cmajor < 0) {
error = EINVAL;
goto out;
}
if ((*bmajor >= 0 && bdevsw[*bmajor] != NULL) ||
cdevsw[*cmajor] != NULL) {
error = EEXIST;
goto out;
}
break;
}
/*
* XXX This should allocate what it needs up front so we never
* need to flail around trying to unwind.
*/
error = bdevsw_attach(bdev, bmajor);
if (error != 0)
goto out;
error = cdevsw_attach(cdev, cmajor);
if (error != 0) {
devsw_detach_locked(bdev, NULL);
goto out;
}
/*
* If we already found a conv, we're done. Otherwise, find an
* empty slot or extend the table.
*/
if (i < max_devsw_convs) {
error = 0;
goto out;
}
for (i = 0; i < max_devsw_convs; i++) {
if (devsw_conv[i].d_name == NULL)
break;
}
if (i == max_devsw_convs) {
struct devsw_conv *newptr;
int old_convs, new_convs;
old_convs = max_devsw_convs;
new_convs = old_convs + 1;
newptr = kmem_zalloc(new_convs * DEVSWCONV_SIZE, KM_NOSLEEP);
if (newptr == NULL) {
devsw_detach_locked(bdev, cdev);
error = ENOMEM;
goto out;
}
newptr[old_convs].d_name = NULL;
newptr[old_convs].d_bmajor = -1;
newptr[old_convs].d_cmajor = -1;
memcpy(newptr, devsw_conv, old_convs * DEVSWCONV_SIZE);
if (devsw_conv != devsw_conv0)
kmem_free(devsw_conv, old_convs * DEVSWCONV_SIZE);
devsw_conv = newptr;
max_devsw_convs = new_convs;
}
name = kmem_strdupsize(devname, NULL, KM_NOSLEEP);
if (name == NULL) {
devsw_detach_locked(bdev, cdev);
error = ENOMEM;
goto out;
}
devsw_conv[i].d_name = name;
devsw_conv[i].d_bmajor = *bmajor;
devsw_conv[i].d_cmajor = *cmajor;
error = 0;
out:
mutex_exit(&device_lock);
return error;
}
static int
bdevsw_attach(const struct bdevsw *devsw, devmajor_t *devmajor)
{
const struct bdevsw **newbdevsw = NULL;
struct devswref *newbdevswref = NULL;
struct localcount *lc;
devmajor_t bmajor;
int i;
KASSERT(mutex_owned(&device_lock));
if (devsw == NULL)
return 0;
if (*devmajor < 0) {
for (bmajor = sys_bdevsws; bmajor < max_bdevsws; bmajor++) {
if (bdevsw[bmajor] != NULL)
continue;
for (i = 0; i < max_devsw_convs; i++) {
if (devsw_conv[i].d_bmajor == bmajor)
break;
}
if (i != max_devsw_convs)
continue;
break;
}
*devmajor = bmajor;
}
if (*devmajor >= MAXDEVSW) {
printf("%s: block majors exhausted\n", __func__);
return ENOMEM;
}
if (bdevswref == NULL) {
newbdevswref = kmem_zalloc(MAXDEVSW * sizeof(newbdevswref[0]),
KM_NOSLEEP);
if (newbdevswref == NULL)
return ENOMEM;
atomic_store_release(&bdevswref, newbdevswref);
}
if (*devmajor >= max_bdevsws) {
KASSERT(bdevsw == bdevsw0);
newbdevsw = kmem_zalloc(MAXDEVSW * sizeof(newbdevsw[0]),
KM_NOSLEEP);
if (newbdevsw == NULL)
return ENOMEM;
memcpy(newbdevsw, bdevsw, max_bdevsws * sizeof(bdevsw[0]));
atomic_store_release(&bdevsw, newbdevsw);
atomic_store_release(&max_bdevsws, MAXDEVSW);
}
if (bdevsw[*devmajor] != NULL)
return EEXIST;
KASSERT(bdevswref[*devmajor].dr_lc == NULL);
lc = kmem_zalloc(sizeof(*lc), KM_SLEEP);
localcount_init(lc);
bdevswref[*devmajor].dr_lc = lc;
atomic_store_release(&bdevsw[*devmajor], devsw);
return 0;
}
static int
cdevsw_attach(const struct cdevsw *devsw, devmajor_t *devmajor)
{
const struct cdevsw **newcdevsw = NULL;
struct devswref *newcdevswref = NULL;
struct localcount *lc;
devmajor_t cmajor;
int i;
KASSERT(mutex_owned(&device_lock));
if (*devmajor < 0) {
for (cmajor = sys_cdevsws; cmajor < max_cdevsws; cmajor++) {
if (cdevsw[cmajor] != NULL)
continue;
for (i = 0; i < max_devsw_convs; i++) {
if (devsw_conv[i].d_cmajor == cmajor)
break;
}
if (i != max_devsw_convs)
continue;
break;
}
*devmajor = cmajor;
}
if (*devmajor >= MAXDEVSW) {
printf("%s: character majors exhausted\n", __func__);
return ENOMEM;
}
if (cdevswref == NULL) {
newcdevswref = kmem_zalloc(MAXDEVSW * sizeof(newcdevswref[0]),
KM_NOSLEEP);
if (newcdevswref == NULL)
return ENOMEM;
atomic_store_release(&cdevswref, newcdevswref);
}
if (*devmajor >= max_cdevsws) {
KASSERT(cdevsw == cdevsw0);
newcdevsw = kmem_zalloc(MAXDEVSW * sizeof(newcdevsw[0]),
KM_NOSLEEP);
if (newcdevsw == NULL)
return ENOMEM;
memcpy(newcdevsw, cdevsw, max_cdevsws * sizeof(cdevsw[0]));
atomic_store_release(&cdevsw, newcdevsw);
atomic_store_release(&max_cdevsws, MAXDEVSW);
}
if (cdevsw[*devmajor] != NULL)
return EEXIST;
KASSERT(cdevswref[*devmajor].dr_lc == NULL);
lc = kmem_zalloc(sizeof(*lc), KM_SLEEP);
localcount_init(lc);
cdevswref[*devmajor].dr_lc = lc;
atomic_store_release(&cdevsw[*devmajor], devsw);
return 0;
}
static void
devsw_detach_locked(const struct bdevsw *bdev, const struct cdevsw *cdev)
{
int bi, ci = -1/*XXXGCC*/, di;
struct cfdriver *cd;
device_t dv;
KASSERT(mutex_owned(&device_lock));
/*
* If this is wired to an autoconf device, make sure the device
* has no more instances. No locking here because under
* correct use of devsw_detach, none of this state can change
* at this point.
*/
if (cdev != NULL && (cd = cdev->d_cfdriver) != NULL) {
for (di = 0; di < cd->cd_ndevs; di++) {
KASSERTMSG((dv = cd->cd_devs[di]) == NULL,
"detaching character device driver %s"
" still has attached unit %s",
cd->cd_name, device_xname(dv));
}
}
if (bdev != NULL && (cd = bdev->d_cfdriver) != NULL) {
for (di = 0; di < cd->cd_ndevs; di++) {
KASSERTMSG((dv = cd->cd_devs[di]) == NULL,
"detaching block device driver %s"
" still has attached unit %s",
cd->cd_name, device_xname(dv));
}
}
/* Prevent new references. */
if (bdev != NULL) {
for (bi = 0; bi < max_bdevsws; bi++) {
if (bdevsw[bi] != bdev)
continue;
atomic_store_relaxed(&bdevsw[bi], NULL);
break;
}
KASSERT(bi < max_bdevsws);
}
if (cdev != NULL) {
for (ci = 0; ci < max_cdevsws; ci++) {
if (cdevsw[ci] != cdev)
continue;
atomic_store_relaxed(&cdevsw[ci], NULL);
break;
}
KASSERT(ci < max_cdevsws);
}
if (bdev == NULL && cdev == NULL) /* XXX possible? */
return;
/*
* Wait for all bdevsw_lookup_acquire, cdevsw_lookup_acquire
* calls to notice that the devsw is gone.
*
* XXX Despite the use of the pserialize_read_enter/exit API
* elsewhere in this file, we use xc_barrier here instead of
* pserialize_perform -- because devsw_init is too early for
* pserialize_create. Either pserialize_create should be made
* to work earlier, or it should be nixed altogether. Until
* that is fixed, xc_barrier will serve the same purpose.
*/
xc_barrier(0);
/*
* Wait for all references to drain. It is the caller's
* responsibility to ensure that at this point, there are no
* extant open instances and all new d_open calls will fail.
*
* Note that localcount_drain may release and reacquire
* device_lock.
*/
if (bdev != NULL) {
localcount_drain(bdevswref[bi].dr_lc,
&devsw_cv, &device_lock);
localcount_fini(bdevswref[bi].dr_lc);
kmem_free(bdevswref[bi].dr_lc, sizeof(*bdevswref[bi].dr_lc));
bdevswref[bi].dr_lc = NULL;
}
if (cdev != NULL) {
localcount_drain(cdevswref[ci].dr_lc,
&devsw_cv, &device_lock);
localcount_fini(cdevswref[ci].dr_lc);
kmem_free(cdevswref[ci].dr_lc, sizeof(*cdevswref[ci].dr_lc));
cdevswref[ci].dr_lc = NULL;
}
}
void
devsw_detach(const struct bdevsw *bdev, const struct cdevsw *cdev)
{
mutex_enter(&device_lock);
devsw_detach_locked(bdev, cdev);
mutex_exit(&device_lock);
}
/*
* Look up a block device by number.
*
* => Caller must ensure that the device is attached.
*/
const struct bdevsw *
bdevsw_lookup(dev_t dev)
{
devmajor_t bmajor;
if (dev == NODEV)
return NULL;
bmajor = major(dev);
if (bmajor < 0 || bmajor >= atomic_load_relaxed(&max_bdevsws))
return NULL;
return atomic_load_consume(&bdevsw)[bmajor];
}
static const struct bdevsw *
bdevsw_lookup_acquire(dev_t dev, struct localcount **lcp)
{
devmajor_t bmajor;
const struct bdevsw *bdev = NULL, *const *curbdevsw;
struct devswref *curbdevswref;
int s;
if (dev == NODEV)
return NULL;
bmajor = major(dev);
if (bmajor < 0)
return NULL;
s = pserialize_read_enter();
/*
* max_bdevsws never goes down, so it is safe to rely on this
* condition without any locking for the array access below.
* Test sys_bdevsws first so we can avoid the memory barrier in
* that case.
*/
if (bmajor >= sys_bdevsws &&
bmajor >= atomic_load_acquire(&max_bdevsws))
goto out;
curbdevsw = atomic_load_consume(&bdevsw);
if ((bdev = atomic_load_consume(&curbdevsw[bmajor])) == NULL)
goto out;
curbdevswref = atomic_load_consume(&bdevswref);
if (curbdevswref == NULL) {
*lcp = NULL;
} else if ((*lcp = curbdevswref[bmajor].dr_lc) != NULL) {
localcount_acquire(*lcp);
}
out:
pserialize_read_exit(s);
return bdev;
}
static void
bdevsw_release(const struct bdevsw *bdev, struct localcount *lc)
{
if (lc == NULL)
return;
localcount_release(lc, &devsw_cv, &device_lock);
}
/*
* Look up a character device by number.
*
* => Caller must ensure that the device is attached.
*/
const struct cdevsw *
cdevsw_lookup(dev_t dev)
{
devmajor_t cmajor;
if (dev == NODEV)
return NULL;
cmajor = major(dev);
if (cmajor < 0 || cmajor >= atomic_load_relaxed(&max_cdevsws))
return NULL;
return atomic_load_consume(&cdevsw)[cmajor];
}
static const struct cdevsw *
cdevsw_lookup_acquire(dev_t dev, struct localcount **lcp)
{
devmajor_t cmajor;
const struct cdevsw *cdev = NULL, *const *curcdevsw;
struct devswref *curcdevswref;
int s;
if (dev == NODEV)
return NULL;
cmajor = major(dev);
if (cmajor < 0)
return NULL;
s = pserialize_read_enter();
/*
* max_cdevsws never goes down, so it is safe to rely on this
* condition without any locking for the array access below.
* Test sys_cdevsws first so we can avoid the memory barrier in
* that case.
*/
if (cmajor >= sys_cdevsws &&
cmajor >= atomic_load_acquire(&max_cdevsws))
goto out;
curcdevsw = atomic_load_consume(&cdevsw);
if ((cdev = atomic_load_consume(&curcdevsw[cmajor])) == NULL)
goto out;
curcdevswref = atomic_load_consume(&cdevswref);
if (curcdevswref == NULL) {
*lcp = NULL;
} else if ((*lcp = curcdevswref[cmajor].dr_lc) != NULL) {
localcount_acquire(*lcp);
}
out:
pserialize_read_exit(s);
return cdev;
}
static void
cdevsw_release(const struct cdevsw *cdev, struct localcount *lc)
{
if (lc == NULL)
return;
localcount_release(lc, &devsw_cv, &device_lock);
}
/*
* Look up a block device by reference to its operations set.
*
* => Caller must ensure that the device is not detached, and therefore
* that the returned major is still valid when dereferenced.
*/
devmajor_t
bdevsw_lookup_major(const struct bdevsw *bdev)
{
const struct bdevsw *const *curbdevsw;
devmajor_t bmajor, bmax;
bmax = atomic_load_acquire(&max_bdevsws);
curbdevsw = atomic_load_consume(&bdevsw);
for (bmajor = 0; bmajor < bmax; bmajor++) {
if (atomic_load_relaxed(&curbdevsw[bmajor]) == bdev)
return bmajor;
}
return NODEVMAJOR;
}
/*
* Look up a character device by reference to its operations set.
*
* => Caller must ensure that the device is not detached, and therefore
* that the returned major is still valid when dereferenced.
*/
devmajor_t
cdevsw_lookup_major(const struct cdevsw *cdev)
{
const struct cdevsw *const *curcdevsw;
devmajor_t cmajor, cmax;
cmax = atomic_load_acquire(&max_cdevsws);
curcdevsw = atomic_load_consume(&cdevsw);
for (cmajor = 0; cmajor < cmax; cmajor++) {
if (atomic_load_relaxed(&curcdevsw[cmajor]) == cdev)
return cmajor;
}
return NODEVMAJOR;
}
/*
* Convert from block major number to name.
*
* => Caller must ensure that the device is not detached, and therefore
* that the name pointer is still valid when dereferenced.
*/
const char *
devsw_blk2name(devmajor_t bmajor)
{
const char *name;
devmajor_t cmajor;
int i;
name = NULL;
cmajor = -1;
mutex_enter(&device_lock);
if (bmajor < 0 || bmajor >= max_bdevsws || bdevsw[bmajor] == NULL) {
mutex_exit(&device_lock);
return NULL;
}
for (i = 0; i < max_devsw_convs; i++) {
if (devsw_conv[i].d_bmajor == bmajor) {
cmajor = devsw_conv[i].d_cmajor;
break;
}
}
if (cmajor >= 0 && cmajor < max_cdevsws && cdevsw[cmajor] != NULL)
name = devsw_conv[i].d_name;
mutex_exit(&device_lock);
return name;
}
/*
* Convert char major number to device driver name.
*/
const char *
cdevsw_getname(devmajor_t major)
{
const char *name;
int i;
name = NULL;
if (major < 0)
return NULL;
mutex_enter(&device_lock);
for (i = 0; i < max_devsw_convs; i++) {
if (devsw_conv[i].d_cmajor == major) {
name = devsw_conv[i].d_name;
break;
}
}
mutex_exit(&device_lock);
return name;
}
/*
* Convert block major number to device driver name.
*/
const char *
bdevsw_getname(devmajor_t major)
{
const char *name;
int i;
name = NULL;
if (major < 0)
return NULL;
mutex_enter(&device_lock);
for (i = 0; i < max_devsw_convs; i++) {
if (devsw_conv[i].d_bmajor == major) {
name = devsw_conv[i].d_name;
break;
}
}
mutex_exit(&device_lock);
return name;
}
/*
* Convert from device name to block major number.
*
* => Caller must ensure that the device is not detached, and therefore
* that the major number is still valid when dereferenced.
*/
devmajor_t
devsw_name2blk(const char *name, char *devname, size_t devnamelen)
{
struct devsw_conv *conv;
devmajor_t bmajor;
int i;
if (name == NULL)
return NODEVMAJOR;
mutex_enter(&device_lock);
for (i = 0; i < max_devsw_convs; i++) {
size_t len;