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15#include <linux/errno.h>
16#include <linux/stddef.h>
17#include <linux/slab.h>
18#include <linux/module.h>
19#include <linux/string.h>
20#include <linux/relay.h>
21#include <linux/vmalloc.h>
22#include <linux/mm.h>
23#include <linux/cpu.h>
24#include <linux/splice.h>
25
26
27static DEFINE_MUTEX(relay_channels_mutex);
28static LIST_HEAD(relay_channels);
29
30
31
32
33static void relay_file_mmap_close(struct vm_area_struct *vma)
34{
35 struct rchan_buf *buf = vma->vm_private_data;
36 buf->chan->cb->buf_unmapped(buf, vma->vm_file);
37}
38
39
40
41
42static struct page *relay_buf_nopage(struct vm_area_struct *vma,
43 unsigned long address,
44 int *type)
45{
46 struct page *page;
47 struct rchan_buf *buf = vma->vm_private_data;
48 unsigned long offset = address - vma->vm_start;
49
50 if (address > vma->vm_end)
51 return NOPAGE_SIGBUS;
52 if (!buf)
53 return NOPAGE_OOM;
54
55 page = vmalloc_to_page(buf->start + offset);
56 if (!page)
57 return NOPAGE_OOM;
58 get_page(page);
59
60 if (type)
61 *type = VM_FAULT_MINOR;
62
63 return page;
64}
65
66
67
68
69static struct vm_operations_struct relay_file_mmap_ops = {
70 .nopage = relay_buf_nopage,
71 .close = relay_file_mmap_close,
72};
73
74
75
76
77
78
79
80
81
82
83static int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma)
84{
85 unsigned long length = vma->vm_end - vma->vm_start;
86 struct file *filp = vma->vm_file;
87
88 if (!buf)
89 return -EBADF;
90
91 if (length != (unsigned long)buf->chan->alloc_size)
92 return -EINVAL;
93
94 vma->vm_ops = &relay_file_mmap_ops;
95 vma->vm_private_data = buf;
96 buf->chan->cb->buf_mapped(buf, filp);
97
98 return 0;
99}
100
101
102
103
104
105
106
107
108
109static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size)
110{
111 void *mem;
112 unsigned int i, j, n_pages;
113
114 *size = PAGE_ALIGN(*size);
115 n_pages = *size >> PAGE_SHIFT;
116
117 buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
118 if (!buf->page_array)
119 return NULL;
120
121 for (i = 0; i < n_pages; i++) {
122 buf->page_array[i] = alloc_page(GFP_KERNEL);
123 if (unlikely(!buf->page_array[i]))
124 goto depopulate;
125 set_page_private(buf->page_array[i], (unsigned long)buf);
126 }
127 mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL);
128 if (!mem)
129 goto depopulate;
130
131 memset(mem, 0, *size);
132 buf->page_count = n_pages;
133 return mem;
134
135depopulate:
136 for (j = 0; j < i; j++)
137 __free_page(buf->page_array[j]);
138 kfree(buf->page_array);
139 return NULL;
140}
141
142
143
144
145
146
147
148static struct rchan_buf *relay_create_buf(struct rchan *chan)
149{
150 struct rchan_buf *buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL);
151 if (!buf)
152 return NULL;
153
154 buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL);
155 if (!buf->padding)
156 goto free_buf;
157
158 buf->start = relay_alloc_buf(buf, &chan->alloc_size);
159 if (!buf->start)
160 goto free_buf;
161
162 buf->chan = chan;
163 kref_get(&buf->chan->kref);
164 return buf;
165
166free_buf:
167 kfree(buf->padding);
168 kfree(buf);
169 return NULL;
170}
171
172
173
174
175
176
177
178static void relay_destroy_channel(struct kref *kref)
179{
180 struct rchan *chan = container_of(kref, struct rchan, kref);
181 kfree(chan);
182}
183
184
185
186
187
188static void relay_destroy_buf(struct rchan_buf *buf)
189{
190 struct rchan *chan = buf->chan;
191 unsigned int i;
192
193 if (likely(buf->start)) {
194 vunmap(buf->start);
195 for (i = 0; i < buf->page_count; i++)
196 __free_page(buf->page_array[i]);
197 kfree(buf->page_array);
198 }
199 chan->buf[buf->cpu] = NULL;
200 kfree(buf->padding);
201 kfree(buf);
202 kref_put(&chan->kref, relay_destroy_channel);
203}
204
205
206
207
208
209
210
211
212
213static void relay_remove_buf(struct kref *kref)
214{
215 struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref);
216 buf->chan->cb->remove_buf_file(buf->dentry);
217 relay_destroy_buf(buf);
218}
219
220
221
222
223
224
225
226static int relay_buf_empty(struct rchan_buf *buf)
227{
228 return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1;
229}
230
231
232
233
234
235
236
237int relay_buf_full(struct rchan_buf *buf)
238{
239 size_t ready = buf->subbufs_produced - buf->subbufs_consumed;
240 return (ready >= buf->chan->n_subbufs) ? 1 : 0;
241}
242EXPORT_SYMBOL_GPL(relay_buf_full);
243
244
245
246
247
248
249
250
251
252
253
254
255
256static int subbuf_start_default_callback (struct rchan_buf *buf,
257 void *subbuf,
258 void *prev_subbuf,
259 size_t prev_padding)
260{
261 if (relay_buf_full(buf))
262 return 0;
263
264 return 1;
265}
266
267
268
269
270static void buf_mapped_default_callback(struct rchan_buf *buf,
271 struct file *filp)
272{
273}
274
275
276
277
278static void buf_unmapped_default_callback(struct rchan_buf *buf,
279 struct file *filp)
280{
281}
282
283
284
285
286static struct dentry *create_buf_file_default_callback(const char *filename,
287 struct dentry *parent,
288 int mode,
289 struct rchan_buf *buf,
290 int *is_global)
291{
292 return NULL;
293}
294
295
296
297
298static int remove_buf_file_default_callback(struct dentry *dentry)
299{
300 return -EINVAL;
301}
302
303
304static struct rchan_callbacks default_channel_callbacks = {
305 .subbuf_start = subbuf_start_default_callback,
306 .buf_mapped = buf_mapped_default_callback,
307 .buf_unmapped = buf_unmapped_default_callback,
308 .create_buf_file = create_buf_file_default_callback,
309 .remove_buf_file = remove_buf_file_default_callback,
310};
311
312
313
314
315
316
317
318static void wakeup_readers(unsigned long data)
319{
320 struct rchan_buf *buf = (struct rchan_buf *)data;
321 wake_up_interruptible(&buf->read_wait);
322}
323
324
325
326
327
328
329
330
331static void __relay_reset(struct rchan_buf *buf, unsigned int init)
332{
333 size_t i;
334
335 if (init) {
336 init_waitqueue_head(&buf->read_wait);
337 kref_init(&buf->kref);
338 setup_timer(&buf->timer, wakeup_readers, (unsigned long)buf);
339 } else
340 del_timer_sync(&buf->timer);
341
342 buf->subbufs_produced = 0;
343 buf->subbufs_consumed = 0;
344 buf->bytes_consumed = 0;
345 buf->finalized = 0;
346 buf->data = buf->start;
347 buf->offset = 0;
348
349 for (i = 0; i < buf->chan->n_subbufs; i++)
350 buf->padding[i] = 0;
351
352 buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0);
353}
354
355
356
357
358
359
360
361
362
363
364
365
366void relay_reset(struct rchan *chan)
367{
368 unsigned int i;
369
370 if (!chan)
371 return;
372
373 if (chan->is_global && chan->buf[0]) {
374 __relay_reset(chan->buf[0], 0);
375 return;
376 }
377
378 mutex_lock(&relay_channels_mutex);
379 for_each_online_cpu(i)
380 if (chan->buf[i])
381 __relay_reset(chan->buf[i], 0);
382 mutex_unlock(&relay_channels_mutex);
383}
384EXPORT_SYMBOL_GPL(relay_reset);
385
386
387
388
389
390
391static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
392{
393 struct rchan_buf *buf = NULL;
394 struct dentry *dentry;
395 char *tmpname;
396
397 if (chan->is_global)
398 return chan->buf[0];
399
400 tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL);
401 if (!tmpname)
402 goto end;
403 snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu);
404
405 buf = relay_create_buf(chan);
406 if (!buf)
407 goto free_name;
408
409 buf->cpu = cpu;
410 __relay_reset(buf, 1);
411
412
413 dentry = chan->cb->create_buf_file(tmpname, chan->parent, S_IRUSR,
414 buf, &chan->is_global);
415 if (!dentry)
416 goto free_buf;
417
418 buf->dentry = dentry;
419
420 if(chan->is_global) {
421 chan->buf[0] = buf;
422 buf->cpu = 0;
423 }
424
425 goto free_name;
426
427free_buf:
428 relay_destroy_buf(buf);
429 buf = NULL;
430free_name:
431 kfree(tmpname);
432end:
433 return buf;
434}
435
436
437
438
439
440
441
442
443
444static void relay_close_buf(struct rchan_buf *buf)
445{
446 buf->finalized = 1;
447 del_timer_sync(&buf->timer);
448 kref_put(&buf->kref, relay_remove_buf);
449}
450
451static void setup_callbacks(struct rchan *chan,
452 struct rchan_callbacks *cb)
453{
454 if (!cb) {
455 chan->cb = &default_channel_callbacks;
456 return;
457 }
458
459 if (!cb->subbuf_start)
460 cb->subbuf_start = subbuf_start_default_callback;
461 if (!cb->buf_mapped)
462 cb->buf_mapped = buf_mapped_default_callback;
463 if (!cb->buf_unmapped)
464 cb->buf_unmapped = buf_unmapped_default_callback;
465 if (!cb->create_buf_file)
466 cb->create_buf_file = create_buf_file_default_callback;
467 if (!cb->remove_buf_file)
468 cb->remove_buf_file = remove_buf_file_default_callback;
469 chan->cb = cb;
470}
471
472
473
474
475
476
477
478
479
480static int __cpuinit relay_hotcpu_callback(struct notifier_block *nb,
481 unsigned long action,
482 void *hcpu)
483{
484 unsigned int hotcpu = (unsigned long)hcpu;
485 struct rchan *chan;
486
487 switch(action) {
488 case CPU_UP_PREPARE:
489 case CPU_UP_PREPARE_FROZEN:
490 mutex_lock(&relay_channels_mutex);
491 list_for_each_entry(chan, &relay_channels, list) {
492 if (chan->buf[hotcpu])
493 continue;
494 chan->buf[hotcpu] = relay_open_buf(chan, hotcpu);
495 if(!chan->buf[hotcpu]) {
496 printk(KERN_ERR
497 "relay_hotcpu_callback: cpu %d buffer "
498 "creation failed\n", hotcpu);
499 mutex_unlock(&relay_channels_mutex);
500 return NOTIFY_BAD;
501 }
502 }
503 mutex_unlock(&relay_channels_mutex);
504 break;
505 case CPU_DEAD:
506 case CPU_DEAD_FROZEN:
507
508
509 break;
510 }
511 return NOTIFY_OK;
512}
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530struct rchan *relay_open(const char *base_filename,
531 struct dentry *parent,
532 size_t subbuf_size,
533 size_t n_subbufs,
534 struct rchan_callbacks *cb,
535 void *private_data)
536{
537 unsigned int i;
538 struct rchan *chan;
539 if (!base_filename)
540 return NULL;
541
542 if (!(subbuf_size && n_subbufs))
543 return NULL;
544
545 chan = kzalloc(sizeof(struct rchan), GFP_KERNEL);
546 if (!chan)
547 return NULL;
548
549 chan->version = RELAYFS_CHANNEL_VERSION;
550 chan->n_subbufs = n_subbufs;
551 chan->subbuf_size = subbuf_size;
552 chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs);
553 chan->parent = parent;
554 chan->private_data = private_data;
555 strlcpy(chan->base_filename, base_filename, NAME_MAX);
556 setup_callbacks(chan, cb);
557 kref_init(&chan->kref);
558
559 mutex_lock(&relay_channels_mutex);
560 for_each_online_cpu(i) {
561 chan->buf[i] = relay_open_buf(chan, i);
562 if (!chan->buf[i])
563 goto free_bufs;
564 }
565 list_add(&chan->list, &relay_channels);
566 mutex_unlock(&relay_channels_mutex);
567
568 return chan;
569
570free_bufs:
571 for_each_online_cpu(i) {
572 if (!chan->buf[i])
573 break;
574 relay_close_buf(chan->buf[i]);
575 }
576
577 kref_put(&chan->kref, relay_destroy_channel);
578 mutex_unlock(&relay_channels_mutex);
579 return NULL;
580}
581EXPORT_SYMBOL_GPL(relay_open);
582
583
584
585
586
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588
589
590
591
592
593size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length)
594{
595 void *old, *new;
596 size_t old_subbuf, new_subbuf;
597
598 if (unlikely(length > buf->chan->subbuf_size))
599 goto toobig;
600
601 if (buf->offset != buf->chan->subbuf_size + 1) {
602 buf->prev_padding = buf->chan->subbuf_size - buf->offset;
603 old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
604 buf->padding[old_subbuf] = buf->prev_padding;
605 buf->subbufs_produced++;
606 buf->dentry->d_inode->i_size += buf->chan->subbuf_size -
607 buf->padding[old_subbuf];
608 smp_mb();
609 if (waitqueue_active(&buf->read_wait))
610
611
612
613
614
615
616 __mod_timer(&buf->timer, jiffies + 1);
617 }
618
619 old = buf->data;
620 new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
621 new = buf->start + new_subbuf * buf->chan->subbuf_size;
622 buf->offset = 0;
623 if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) {
624 buf->offset = buf->chan->subbuf_size + 1;
625 return 0;
626 }
627 buf->data = new;
628 buf->padding[new_subbuf] = 0;
629
630 if (unlikely(length + buf->offset > buf->chan->subbuf_size))
631 goto toobig;
632
633 return length;
634
635toobig:
636 buf->chan->last_toobig = length;
637 return 0;
638}
639EXPORT_SYMBOL_GPL(relay_switch_subbuf);
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654void relay_subbufs_consumed(struct rchan *chan,
655 unsigned int cpu,
656 size_t subbufs_consumed)
657{
658 struct rchan_buf *buf;
659
660 if (!chan)
661 return;
662
663 if (cpu >= NR_CPUS || !chan->buf[cpu])
664 return;
665
666 buf = chan->buf[cpu];
667 buf->subbufs_consumed += subbufs_consumed;
668 if (buf->subbufs_consumed > buf->subbufs_produced)
669 buf->subbufs_consumed = buf->subbufs_produced;
670}
671EXPORT_SYMBOL_GPL(relay_subbufs_consumed);
672
673
674
675
676
677
678
679void relay_close(struct rchan *chan)
680{
681 unsigned int i;
682
683 if (!chan)
684 return;
685
686 mutex_lock(&relay_channels_mutex);
687 if (chan->is_global && chan->buf[0])
688 relay_close_buf(chan->buf[0]);
689 else
690 for_each_possible_cpu(i)
691 if (chan->buf[i])
692 relay_close_buf(chan->buf[i]);
693
694 if (chan->last_toobig)
695 printk(KERN_WARNING "relay: one or more items not logged "
696 "[item size (%Zd) > sub-buffer size (%Zd)]\n",
697 chan->last_toobig, chan->subbuf_size);
698
699 list_del(&chan->list);
700 kref_put(&chan->kref, relay_destroy_channel);
701 mutex_unlock(&relay_channels_mutex);
702}
703EXPORT_SYMBOL_GPL(relay_close);
704
705
706
707
708
709
710
711void relay_flush(struct rchan *chan)
712{
713 unsigned int i;
714
715 if (!chan)
716 return;
717
718 if (chan->is_global && chan->buf[0]) {
719 relay_switch_subbuf(chan->buf[0], 0);
720 return;
721 }
722
723 mutex_lock(&relay_channels_mutex);
724 for_each_possible_cpu(i)
725 if (chan->buf[i])
726 relay_switch_subbuf(chan->buf[i], 0);
727 mutex_unlock(&relay_channels_mutex);
728}
729EXPORT_SYMBOL_GPL(relay_flush);
730
731
732
733
734
735
736
737
738static int relay_file_open(struct inode *inode, struct file *filp)
739{
740 struct rchan_buf *buf = inode->i_private;
741 kref_get(&buf->kref);
742 filp->private_data = buf;
743
744 return 0;
745}
746
747
748
749
750
751
752
753
754static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma)
755{
756 struct rchan_buf *buf = filp->private_data;
757 return relay_mmap_buf(buf, vma);
758}
759
760
761
762
763
764
765
766
767static unsigned int relay_file_poll(struct file *filp, poll_table *wait)
768{
769 unsigned int mask = 0;
770 struct rchan_buf *buf = filp->private_data;
771
772 if (buf->finalized)
773 return POLLERR;
774
775 if (filp->f_mode & FMODE_READ) {
776 poll_wait(filp, &buf->read_wait, wait);
777 if (!relay_buf_empty(buf))
778 mask |= POLLIN | POLLRDNORM;
779 }
780
781 return mask;
782}
783
784
785
786
787
788
789
790
791
792static int relay_file_release(struct inode *inode, struct file *filp)
793{
794 struct rchan_buf *buf = filp->private_data;
795 kref_put(&buf->kref, relay_remove_buf);
796
797 return 0;
798}
799
800
801
802
803static void relay_file_read_consume(struct rchan_buf *buf,
804 size_t read_pos,
805 size_t bytes_consumed)
806{
807 size_t subbuf_size = buf->chan->subbuf_size;
808 size_t n_subbufs = buf->chan->n_subbufs;
809 size_t read_subbuf;
810
811 if (buf->bytes_consumed + bytes_consumed > subbuf_size) {
812 relay_subbufs_consumed(buf->chan, buf->cpu, 1);
813 buf->bytes_consumed = 0;
814 }
815
816 buf->bytes_consumed += bytes_consumed;
817 if (!read_pos)
818 read_subbuf = buf->subbufs_consumed % n_subbufs;
819 else
820 read_subbuf = read_pos / buf->chan->subbuf_size;
821 if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) {
822 if ((read_subbuf == buf->subbufs_produced % n_subbufs) &&
823 (buf->offset == subbuf_size))
824 return;
825 relay_subbufs_consumed(buf->chan, buf->cpu, 1);
826 buf->bytes_consumed = 0;
827 }
828}
829
830
831
832
833static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos)
834{
835 size_t subbuf_size = buf->chan->subbuf_size;
836 size_t n_subbufs = buf->chan->n_subbufs;
837 size_t produced = buf->subbufs_produced;
838 size_t consumed = buf->subbufs_consumed;
839
840 relay_file_read_consume(buf, read_pos, 0);
841
842 if (unlikely(buf->offset > subbuf_size)) {
843 if (produced == consumed)
844 return 0;
845 return 1;
846 }
847
848 if (unlikely(produced - consumed >= n_subbufs)) {
849 consumed = produced - n_subbufs + 1;
850 buf->subbufs_consumed = consumed;
851 buf->bytes_consumed = 0;
852 }
853
854 produced = (produced % n_subbufs) * subbuf_size + buf->offset;
855 consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed;
856
857 if (consumed > produced)
858 produced += n_subbufs * subbuf_size;
859
860 if (consumed == produced)
861 return 0;
862
863 return 1;
864}
865
866
867
868
869
870
871static size_t relay_file_read_subbuf_avail(size_t read_pos,
872 struct rchan_buf *buf)
873{
874 size_t padding, avail = 0;
875 size_t read_subbuf, read_offset, write_subbuf, write_offset;
876 size_t subbuf_size = buf->chan->subbuf_size;
877
878 write_subbuf = (buf->data - buf->start) / subbuf_size;
879 write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
880 read_subbuf = read_pos / subbuf_size;
881 read_offset = read_pos % subbuf_size;
882 padding = buf->padding[read_subbuf];
883
884 if (read_subbuf == write_subbuf) {
885 if (read_offset + padding < write_offset)
886 avail = write_offset - (read_offset + padding);
887 } else
888 avail = (subbuf_size - padding) - read_offset;
889
890 return avail;
891}
892
893
894
895
896
897
898
899
900
901
902static size_t relay_file_read_start_pos(size_t read_pos,
903 struct rchan_buf *buf)
904{
905 size_t read_subbuf, padding, padding_start, padding_end;
906 size_t subbuf_size = buf->chan->subbuf_size;
907 size_t n_subbufs = buf->chan->n_subbufs;
908 size_t consumed = buf->subbufs_consumed % n_subbufs;
909
910 if (!read_pos)
911 read_pos = consumed * subbuf_size + buf->bytes_consumed;
912 read_subbuf = read_pos / subbuf_size;
913 padding = buf->padding[read_subbuf];
914 padding_start = (read_subbuf + 1) * subbuf_size - padding;
915 padding_end = (read_subbuf + 1) * subbuf_size;
916 if (read_pos >= padding_start && read_pos < padding_end) {
917 read_subbuf = (read_subbuf + 1) % n_subbufs;
918 read_pos = read_subbuf * subbuf_size;
919 }
920
921 return read_pos;
922}
923
924
925
926
927
928
929
930static size_t relay_file_read_end_pos(struct rchan_buf *buf,
931 size_t read_pos,
932 size_t count)
933{
934 size_t read_subbuf, padding, end_pos;
935 size_t subbuf_size = buf->chan->subbuf_size;
936 size_t n_subbufs = buf->chan->n_subbufs;
937
938 read_subbuf = read_pos / subbuf_size;
939 padding = buf->padding[read_subbuf];
940 if (read_pos % subbuf_size + count + padding == subbuf_size)
941 end_pos = (read_subbuf + 1) * subbuf_size;
942 else
943 end_pos = read_pos + count;
944 if (end_pos >= subbuf_size * n_subbufs)
945 end_pos = 0;
946
947 return end_pos;
948}
949
950
951
952
953static int subbuf_read_actor(size_t read_start,
954 struct rchan_buf *buf,
955 size_t avail,
956 read_descriptor_t *desc,
957 read_actor_t actor)
958{
959 void *from;
960 int ret = 0;
961
962 from = buf->start + read_start;
963 ret = avail;
964 if (copy_to_user(desc->arg.buf, from, avail)) {
965 desc->error = -EFAULT;
966 ret = 0;
967 }
968 desc->arg.data += ret;
969 desc->written += ret;
970 desc->count -= ret;
971
972 return ret;
973}
974
975typedef int (*subbuf_actor_t) (size_t read_start,
976 struct rchan_buf *buf,
977 size_t avail,
978 read_descriptor_t *desc,
979 read_actor_t actor);
980
981
982
983
984static ssize_t relay_file_read_subbufs(struct file *filp, loff_t *ppos,
985 subbuf_actor_t subbuf_actor,
986 read_actor_t actor,
987 read_descriptor_t *desc)
988{
989 struct rchan_buf *buf = filp->private_data;
990 size_t read_start, avail;
991 int ret;
992
993 if (!desc->count)
994 return 0;
995
996 mutex_lock(&filp->f_path.dentry->d_inode->i_mutex);
997 do {
998 if (!relay_file_read_avail(buf, *ppos))
999 break;
1000
1001 read_start = relay_file_read_start_pos(*ppos, buf);
1002 avail = relay_file_read_subbuf_avail(read_start, buf);
1003 if (!avail)
1004 break;
1005
1006 avail = min(desc->count, avail);
1007 ret = subbuf_actor(read_start, buf, avail, desc, actor);
1008 if (desc->error < 0)
1009 break;
1010
1011 if (ret) {
1012 relay_file_read_consume(buf, read_start, ret);
1013 *ppos = relay_file_read_end_pos(buf, read_start, ret);
1014 }
1015 } while (desc->count && ret);
1016 mutex_unlock(&filp->f_path.dentry->d_inode->i_mutex);
1017
1018 return desc->written;
1019}
1020
1021static ssize_t relay_file_read(struct file *filp,
1022 char __user *buffer,
1023 size_t count,
1024 loff_t *ppos)
1025{
1026 read_descriptor_t desc;
1027 desc.written = 0;
1028 desc.count = count;
1029 desc.arg.buf = buffer;
1030 desc.error = 0;
1031 return relay_file_read_subbufs(filp, ppos, subbuf_read_actor,
1032 NULL, &desc);
1033}
1034
1035static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed)
1036{
1037 rbuf->bytes_consumed += bytes_consumed;
1038
1039 if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) {
1040 relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1);
1041 rbuf->bytes_consumed %= rbuf->chan->subbuf_size;
1042 }
1043}
1044
1045static void relay_pipe_buf_release(struct pipe_inode_info *pipe,
1046 struct pipe_buffer *buf)
1047{
1048 struct rchan_buf *rbuf;
1049
1050 rbuf = (struct rchan_buf *)page_private(buf->page);
1051 relay_consume_bytes(rbuf, buf->private);
1052}
1053
1054static struct pipe_buf_operations relay_pipe_buf_ops = {
1055 .can_merge = 0,
1056 .map = generic_pipe_buf_map,
1057 .unmap = generic_pipe_buf_unmap,
1058 .confirm = generic_pipe_buf_confirm,
1059 .release = relay_pipe_buf_release,
1060 .steal = generic_pipe_buf_steal,
1061 .get = generic_pipe_buf_get,
1062};
1063
1064
1065
1066
1067static int subbuf_splice_actor(struct file *in,
1068 loff_t *ppos,
1069 struct pipe_inode_info *pipe,
1070 size_t len,
1071 unsigned int flags,
1072 int *nonpad_ret)
1073{
1074 unsigned int pidx, poff, total_len, subbuf_pages, ret;
1075 struct rchan_buf *rbuf = in->private_data;
1076 unsigned int subbuf_size = rbuf->chan->subbuf_size;
1077 uint64_t pos = (uint64_t) *ppos;
1078 uint32_t alloc_size = (uint32_t) rbuf->chan->alloc_size;
1079 size_t read_start = (size_t) do_div(pos, alloc_size);
1080 size_t read_subbuf = read_start / subbuf_size;
1081 size_t padding = rbuf->padding[read_subbuf];
1082 size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding;
1083 struct page *pages[PIPE_BUFFERS];
1084 struct partial_page partial[PIPE_BUFFERS];
1085 struct splice_pipe_desc spd = {
1086 .pages = pages,
1087 .nr_pages = 0,
1088 .partial = partial,
1089 .flags = flags,
1090 .ops = &relay_pipe_buf_ops,
1091 };
1092
1093 if (rbuf->subbufs_produced == rbuf->subbufs_consumed)
1094 return 0;
1095
1096
1097
1098
1099 if (len > (subbuf_size - read_start % subbuf_size))
1100 len = subbuf_size - read_start % subbuf_size;
1101
1102 subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT;
1103 pidx = (read_start / PAGE_SIZE) % subbuf_pages;
1104 poff = read_start & ~PAGE_MASK;
1105
1106 for (total_len = 0; spd.nr_pages < subbuf_pages; spd.nr_pages++) {
1107 unsigned int this_len, this_end, private;
1108 unsigned int cur_pos = read_start + total_len;
1109
1110 if (!len)
1111 break;
1112
1113 this_len = min_t(unsigned long, len, PAGE_SIZE - poff);
1114 private = this_len;
1115
1116 spd.pages[spd.nr_pages] = rbuf->page_array[pidx];
1117 spd.partial[spd.nr_pages].offset = poff;
1118
1119 this_end = cur_pos + this_len;
1120 if (this_end >= nonpad_end) {
1121 this_len = nonpad_end - cur_pos;
1122 private = this_len + padding;
1123 }
1124 spd.partial[spd.nr_pages].len = this_len;
1125 spd.partial[spd.nr_pages].private = private;
1126
1127 len -= this_len;
1128 total_len += this_len;
1129 poff = 0;
1130 pidx = (pidx + 1) % subbuf_pages;
1131
1132 if (this_end >= nonpad_end) {
1133 spd.nr_pages++;
1134 break;
1135 }
1136 }
1137
1138 if (!spd.nr_pages)
1139 return 0;
1140
1141 ret = *nonpad_ret = splice_to_pipe(pipe, &spd);
1142 if (ret < 0 || ret < total_len)
1143 return ret;
1144
1145 if (read_start + ret == nonpad_end)
1146 ret += padding;
1147
1148 return ret;
1149}
1150
1151static ssize_t relay_file_splice_read(struct file *in,
1152 loff_t *ppos,
1153 struct pipe_inode_info *pipe,
1154 size_t len,
1155 unsigned int flags)
1156{
1157 ssize_t spliced;
1158 int ret;
1159 int nonpad_ret = 0;
1160
1161 ret = 0;
1162 spliced = 0;
1163
1164 while (len) {
1165 ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret);
1166 if (ret < 0)
1167 break;
1168 else if (!ret) {
1169 if (spliced)
1170 break;
1171 if (flags & SPLICE_F_NONBLOCK) {
1172 ret = -EAGAIN;
1173 break;
1174 }
1175 }
1176
1177 *ppos += ret;
1178 if (ret > len)
1179 len = 0;
1180 else
1181 len -= ret;
1182 spliced += nonpad_ret;
1183 nonpad_ret = 0;
1184 }
1185
1186 if (spliced)
1187 return spliced;
1188
1189 return ret;
1190}
1191
1192const struct file_operations relay_file_operations = {
1193 .open = relay_file_open,
1194 .poll = relay_file_poll,
1195 .mmap = relay_file_mmap,
1196 .read = relay_file_read,
1197 .llseek = no_llseek,
1198 .release = relay_file_release,
1199 .splice_read = relay_file_splice_read,
1200};
1201EXPORT_SYMBOL_GPL(relay_file_operations);
1202
1203static __init int relay_init(void)
1204{
1205
1206 hotcpu_notifier(relay_hotcpu_callback, 0);
1207 return 0;
1208}
1209
1210module_init(relay_init);
1211