Commit | Line | Data |
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3e7ee490 HJ |
1 | /* |
2 | * | |
3 | * Copyright (c) 2009, Microsoft Corporation. | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify it | |
6 | * under the terms and conditions of the GNU General Public License, | |
7 | * version 2, as published by the Free Software Foundation. | |
8 | * | |
9 | * This program is distributed in the hope it will be useful, but WITHOUT | |
10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
12 | * more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License along with | |
15 | * this program; if not, write to the Free Software Foundation, Inc., 59 Temple | |
16 | * Place - Suite 330, Boston, MA 02111-1307 USA. | |
17 | * | |
18 | * Authors: | |
19 | * Haiyang Zhang <haiyangz@microsoft.com> | |
20 | * Hank Janssen <hjanssen@microsoft.com> | |
b2a5a585 | 21 | * K. Y. Srinivasan <kys@microsoft.com> |
3e7ee490 HJ |
22 | * |
23 | */ | |
0a46618d | 24 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
3e7ee490 | 25 | |
a0086dc5 GKH |
26 | #include <linux/kernel.h> |
27 | #include <linux/mm.h> | |
46a97191 | 28 | #include <linux/hyperv.h> |
3f335ea2 | 29 | |
0f2a6619 | 30 | #include "hyperv_vmbus.h" |
3e7ee490 | 31 | |
6fdf3b21 S |
32 | void hv_begin_read(struct hv_ring_buffer_info *rbi) |
33 | { | |
34 | rbi->ring_buffer->interrupt_mask = 1; | |
35848f68 | 35 | mb(); |
6fdf3b21 S |
36 | } |
37 | ||
38 | u32 hv_end_read(struct hv_ring_buffer_info *rbi) | |
39 | { | |
40 | u32 read; | |
41 | u32 write; | |
42 | ||
43 | rbi->ring_buffer->interrupt_mask = 0; | |
35848f68 | 44 | mb(); |
6fdf3b21 S |
45 | |
46 | /* | |
47 | * Now check to see if the ring buffer is still empty. | |
48 | * If it is not, we raced and we need to process new | |
49 | * incoming messages. | |
50 | */ | |
51 | hv_get_ringbuffer_availbytes(rbi, &read, &write); | |
52 | ||
53 | return read; | |
54 | } | |
55 | ||
98fa8cf4 S |
56 | /* |
57 | * When we write to the ring buffer, check if the host needs to | |
58 | * be signaled. Here is the details of this protocol: | |
59 | * | |
60 | * 1. The host guarantees that while it is draining the | |
61 | * ring buffer, it will set the interrupt_mask to | |
62 | * indicate it does not need to be interrupted when | |
63 | * new data is placed. | |
64 | * | |
65 | * 2. The host guarantees that it will completely drain | |
66 | * the ring buffer before exiting the read loop. Further, | |
67 | * once the ring buffer is empty, it will clear the | |
68 | * interrupt_mask and re-check to see if new data has | |
69 | * arrived. | |
70 | */ | |
71 | ||
72 | static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi) | |
73 | { | |
35848f68 | 74 | mb(); |
98fa8cf4 S |
75 | if (rbi->ring_buffer->interrupt_mask) |
76 | return false; | |
77 | ||
78 | /* | |
79 | * This is the only case we need to signal when the | |
80 | * ring transitions from being empty to non-empty. | |
81 | */ | |
82 | if (old_write == rbi->ring_buffer->read_index) | |
83 | return true; | |
84 | ||
85 | return false; | |
86 | } | |
87 | ||
c2b8e520 S |
88 | /* |
89 | * To optimize the flow management on the send-side, | |
90 | * when the sender is blocked because of lack of | |
91 | * sufficient space in the ring buffer, potential the | |
92 | * consumer of the ring buffer can signal the producer. | |
93 | * This is controlled by the following parameters: | |
94 | * | |
95 | * 1. pending_send_sz: This is the size in bytes that the | |
96 | * producer is trying to send. | |
97 | * 2. The feature bit feat_pending_send_sz set to indicate if | |
98 | * the consumer of the ring will signal when the ring | |
99 | * state transitions from being full to a state where | |
100 | * there is room for the producer to send the pending packet. | |
101 | */ | |
102 | ||
103 | static bool hv_need_to_signal_on_read(u32 old_rd, | |
104 | struct hv_ring_buffer_info *rbi) | |
105 | { | |
106 | u32 prev_write_sz; | |
107 | u32 cur_write_sz; | |
108 | u32 r_size; | |
109 | u32 write_loc = rbi->ring_buffer->write_index; | |
110 | u32 read_loc = rbi->ring_buffer->read_index; | |
111 | u32 pending_sz = rbi->ring_buffer->pending_send_sz; | |
112 | ||
113 | /* | |
114 | * If the other end is not blocked on write don't bother. | |
115 | */ | |
116 | if (pending_sz == 0) | |
117 | return false; | |
118 | ||
119 | r_size = rbi->ring_datasize; | |
120 | cur_write_sz = write_loc >= read_loc ? r_size - (write_loc - read_loc) : | |
121 | read_loc - write_loc; | |
122 | ||
123 | prev_write_sz = write_loc >= old_rd ? r_size - (write_loc - old_rd) : | |
124 | old_rd - write_loc; | |
125 | ||
126 | ||
127 | if ((prev_write_sz < pending_sz) && (cur_write_sz >= pending_sz)) | |
128 | return true; | |
129 | ||
130 | return false; | |
131 | } | |
3e7ee490 | 132 | |
b2a5a585 S |
133 | /* |
134 | * hv_get_next_write_location() | |
135 | * | |
136 | * Get the next write location for the specified ring buffer | |
137 | * | |
138 | */ | |
4d643114 | 139 | static inline u32 |
2b8a912e | 140 | hv_get_next_write_location(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 141 | { |
fc8c72eb | 142 | u32 next = ring_info->ring_buffer->write_index; |
3e7ee490 | 143 | |
3e7ee490 HJ |
144 | return next; |
145 | } | |
146 | ||
b2a5a585 S |
147 | /* |
148 | * hv_set_next_write_location() | |
149 | * | |
150 | * Set the next write location for the specified ring buffer | |
151 | * | |
152 | */ | |
3e7ee490 | 153 | static inline void |
2b8a912e | 154 | hv_set_next_write_location(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 155 | u32 next_write_location) |
3e7ee490 | 156 | { |
fc8c72eb | 157 | ring_info->ring_buffer->write_index = next_write_location; |
3e7ee490 HJ |
158 | } |
159 | ||
b2a5a585 S |
160 | /* |
161 | * hv_get_next_read_location() | |
162 | * | |
163 | * Get the next read location for the specified ring buffer | |
164 | */ | |
4d643114 | 165 | static inline u32 |
2b8a912e | 166 | hv_get_next_read_location(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 167 | { |
fc8c72eb | 168 | u32 next = ring_info->ring_buffer->read_index; |
3e7ee490 | 169 | |
3e7ee490 HJ |
170 | return next; |
171 | } | |
172 | ||
b2a5a585 S |
173 | /* |
174 | * hv_get_next_readlocation_withoffset() | |
175 | * | |
176 | * Get the next read location + offset for the specified ring buffer. | |
177 | * This allows the caller to skip | |
178 | */ | |
4d643114 | 179 | static inline u32 |
2b8a912e | 180 | hv_get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info, |
1ac58644 | 181 | u32 offset) |
3e7ee490 | 182 | { |
fc8c72eb | 183 | u32 next = ring_info->ring_buffer->read_index; |
3e7ee490 | 184 | |
fc8c72eb HZ |
185 | next += offset; |
186 | next %= ring_info->ring_datasize; | |
3e7ee490 HJ |
187 | |
188 | return next; | |
189 | } | |
190 | ||
b2a5a585 S |
191 | /* |
192 | * | |
193 | * hv_set_next_read_location() | |
194 | * | |
195 | * Set the next read location for the specified ring buffer | |
196 | * | |
197 | */ | |
3e7ee490 | 198 | static inline void |
2b8a912e | 199 | hv_set_next_read_location(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 200 | u32 next_read_location) |
3e7ee490 | 201 | { |
fc8c72eb | 202 | ring_info->ring_buffer->read_index = next_read_location; |
3e7ee490 HJ |
203 | } |
204 | ||
205 | ||
b2a5a585 S |
206 | /* |
207 | * | |
208 | * hv_get_ring_buffer() | |
209 | * | |
210 | * Get the start of the ring buffer | |
211 | */ | |
8282c400 | 212 | static inline void * |
2b8a912e | 213 | hv_get_ring_buffer(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 214 | { |
fc8c72eb | 215 | return (void *)ring_info->ring_buffer->buffer; |
3e7ee490 HJ |
216 | } |
217 | ||
218 | ||
b2a5a585 S |
219 | /* |
220 | * | |
221 | * hv_get_ring_buffersize() | |
222 | * | |
223 | * Get the size of the ring buffer | |
224 | */ | |
4d643114 | 225 | static inline u32 |
2b8a912e | 226 | hv_get_ring_buffersize(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 227 | { |
fc8c72eb | 228 | return ring_info->ring_datasize; |
3e7ee490 HJ |
229 | } |
230 | ||
b2a5a585 S |
231 | /* |
232 | * | |
233 | * hv_get_ring_bufferindices() | |
234 | * | |
235 | * Get the read and write indices as u64 of the specified ring buffer | |
236 | * | |
237 | */ | |
59471438 | 238 | static inline u64 |
2b8a912e | 239 | hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 240 | { |
fc8c72eb | 241 | return (u64)ring_info->ring_buffer->write_index << 32; |
3e7ee490 HJ |
242 | } |
243 | ||
8f1136ae S |
244 | /* |
245 | * | |
246 | * hv_copyfrom_ringbuffer() | |
247 | * | |
248 | * Helper routine to copy to source from ring buffer. | |
249 | * Assume there is enough room. Handles wrap-around in src case only!! | |
250 | * | |
251 | */ | |
252 | static u32 hv_copyfrom_ringbuffer( | |
253 | struct hv_ring_buffer_info *ring_info, | |
254 | void *dest, | |
255 | u32 destlen, | |
256 | u32 start_read_offset) | |
257 | { | |
258 | void *ring_buffer = hv_get_ring_buffer(ring_info); | |
259 | u32 ring_buffer_size = hv_get_ring_buffersize(ring_info); | |
260 | ||
261 | u32 frag_len; | |
262 | ||
263 | /* wrap-around detected at the src */ | |
264 | if (destlen > ring_buffer_size - start_read_offset) { | |
265 | frag_len = ring_buffer_size - start_read_offset; | |
266 | ||
267 | memcpy(dest, ring_buffer + start_read_offset, frag_len); | |
268 | memcpy(dest + frag_len, ring_buffer, destlen - frag_len); | |
269 | } else | |
270 | ||
271 | memcpy(dest, ring_buffer + start_read_offset, destlen); | |
272 | ||
273 | ||
274 | start_read_offset += destlen; | |
275 | start_read_offset %= ring_buffer_size; | |
276 | ||
277 | return start_read_offset; | |
278 | } | |
279 | ||
280 | ||
7581578d S |
281 | /* |
282 | * | |
283 | * hv_copyto_ringbuffer() | |
284 | * | |
285 | * Helper routine to copy from source to ring buffer. | |
286 | * Assume there is enough room. Handles wrap-around in dest case only!! | |
287 | * | |
288 | */ | |
289 | static u32 hv_copyto_ringbuffer( | |
fc8c72eb HZ |
290 | struct hv_ring_buffer_info *ring_info, |
291 | u32 start_write_offset, | |
292 | void *src, | |
7581578d S |
293 | u32 srclen) |
294 | { | |
295 | void *ring_buffer = hv_get_ring_buffer(ring_info); | |
296 | u32 ring_buffer_size = hv_get_ring_buffersize(ring_info); | |
297 | u32 frag_len; | |
298 | ||
299 | /* wrap-around detected! */ | |
300 | if (srclen > ring_buffer_size - start_write_offset) { | |
301 | frag_len = ring_buffer_size - start_write_offset; | |
302 | memcpy(ring_buffer + start_write_offset, src, frag_len); | |
303 | memcpy(ring_buffer, src + frag_len, srclen - frag_len); | |
304 | } else | |
305 | memcpy(ring_buffer + start_write_offset, src, srclen); | |
3e7ee490 | 306 | |
7581578d S |
307 | start_write_offset += srclen; |
308 | start_write_offset %= ring_buffer_size; | |
309 | ||
310 | return start_write_offset; | |
311 | } | |
3e7ee490 | 312 | |
b2a5a585 S |
313 | /* |
314 | * | |
315 | * hv_ringbuffer_get_debuginfo() | |
316 | * | |
317 | * Get various debug metrics for the specified ring buffer | |
318 | * | |
319 | */ | |
a75b61d5 | 320 | void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info, |
80682b7a | 321 | struct hv_ring_buffer_debug_info *debug_info) |
3e7ee490 | 322 | { |
fc8c72eb HZ |
323 | u32 bytes_avail_towrite; |
324 | u32 bytes_avail_toread; | |
3e7ee490 | 325 | |
fc8c72eb | 326 | if (ring_info->ring_buffer) { |
2b8a912e | 327 | hv_get_ringbuffer_availbytes(ring_info, |
fc8c72eb HZ |
328 | &bytes_avail_toread, |
329 | &bytes_avail_towrite); | |
3e7ee490 | 330 | |
fc8c72eb HZ |
331 | debug_info->bytes_avail_toread = bytes_avail_toread; |
332 | debug_info->bytes_avail_towrite = bytes_avail_towrite; | |
82f8bd40 | 333 | debug_info->current_read_index = |
fc8c72eb | 334 | ring_info->ring_buffer->read_index; |
82f8bd40 | 335 | debug_info->current_write_index = |
fc8c72eb | 336 | ring_info->ring_buffer->write_index; |
82f8bd40 | 337 | debug_info->current_interrupt_mask = |
fc8c72eb | 338 | ring_info->ring_buffer->interrupt_mask; |
3e7ee490 HJ |
339 | } |
340 | } | |
341 | ||
b2a5a585 S |
342 | /* |
343 | * | |
344 | * hv_ringbuffer_init() | |
345 | * | |
346 | *Initialize the ring buffer | |
347 | * | |
348 | */ | |
72a95cbc | 349 | int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 350 | void *buffer, u32 buflen) |
3e7ee490 | 351 | { |
4a1b3acc | 352 | if (sizeof(struct hv_ring_buffer) != PAGE_SIZE) |
3324fb40 | 353 | return -EINVAL; |
3e7ee490 | 354 | |
fc8c72eb | 355 | memset(ring_info, 0, sizeof(struct hv_ring_buffer_info)); |
3e7ee490 | 356 | |
fc8c72eb HZ |
357 | ring_info->ring_buffer = (struct hv_ring_buffer *)buffer; |
358 | ring_info->ring_buffer->read_index = | |
359 | ring_info->ring_buffer->write_index = 0; | |
3e7ee490 | 360 | |
fc8c72eb HZ |
361 | ring_info->ring_size = buflen; |
362 | ring_info->ring_datasize = buflen - sizeof(struct hv_ring_buffer); | |
3e7ee490 | 363 | |
fc8c72eb | 364 | spin_lock_init(&ring_info->ring_lock); |
3e7ee490 HJ |
365 | |
366 | return 0; | |
367 | } | |
368 | ||
b2a5a585 S |
369 | /* |
370 | * | |
371 | * hv_ringbuffer_cleanup() | |
372 | * | |
373 | * Cleanup the ring buffer | |
374 | * | |
375 | */ | |
2dba688b | 376 | void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 377 | { |
3e7ee490 HJ |
378 | } |
379 | ||
b2a5a585 S |
380 | /* |
381 | * | |
382 | * hv_ringbuffer_write() | |
383 | * | |
384 | * Write to the ring buffer | |
385 | * | |
386 | */ | |
633c4dce | 387 | int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info, |
98fa8cf4 | 388 | struct scatterlist *sglist, u32 sgcount, bool *signal) |
3e7ee490 | 389 | { |
4408f531 | 390 | int i = 0; |
fc8c72eb HZ |
391 | u32 bytes_avail_towrite; |
392 | u32 bytes_avail_toread; | |
393 | u32 totalbytes_towrite = 0; | |
3e7ee490 | 394 | |
b219b3f7 | 395 | struct scatterlist *sg; |
66a60543 | 396 | u32 next_write_location; |
98fa8cf4 | 397 | u32 old_write; |
fc8c72eb | 398 | u64 prev_indices = 0; |
a98f96ee | 399 | unsigned long flags; |
3e7ee490 | 400 | |
b219b3f7 | 401 | for_each_sg(sglist, sg, sgcount, i) |
3e7ee490 | 402 | { |
fc8c72eb | 403 | totalbytes_towrite += sg->length; |
3e7ee490 HJ |
404 | } |
405 | ||
fc8c72eb | 406 | totalbytes_towrite += sizeof(u64); |
3e7ee490 | 407 | |
fc8c72eb | 408 | spin_lock_irqsave(&outring_info->ring_lock, flags); |
3e7ee490 | 409 | |
2b8a912e | 410 | hv_get_ringbuffer_availbytes(outring_info, |
fc8c72eb HZ |
411 | &bytes_avail_toread, |
412 | &bytes_avail_towrite); | |
3e7ee490 | 413 | |
3e7ee490 | 414 | |
4408f531 B |
415 | /* If there is only room for the packet, assume it is full. */ |
416 | /* Otherwise, the next time around, we think the ring buffer */ | |
454f18a9 | 417 | /* is empty since the read index == write index */ |
fc8c72eb | 418 | if (bytes_avail_towrite <= totalbytes_towrite) { |
fc8c72eb | 419 | spin_unlock_irqrestore(&outring_info->ring_lock, flags); |
d2598f01 | 420 | return -EAGAIN; |
3e7ee490 HJ |
421 | } |
422 | ||
454f18a9 | 423 | /* Write to the ring buffer */ |
2b8a912e | 424 | next_write_location = hv_get_next_write_location(outring_info); |
3e7ee490 | 425 | |
98fa8cf4 S |
426 | old_write = next_write_location; |
427 | ||
b219b3f7 | 428 | for_each_sg(sglist, sg, sgcount, i) |
3e7ee490 | 429 | { |
2b8a912e | 430 | next_write_location = hv_copyto_ringbuffer(outring_info, |
fc8c72eb | 431 | next_write_location, |
b219b3f7 NP |
432 | sg_virt(sg), |
433 | sg->length); | |
3e7ee490 HJ |
434 | } |
435 | ||
454f18a9 | 436 | /* Set previous packet start */ |
2b8a912e | 437 | prev_indices = hv_get_ring_bufferindices(outring_info); |
3e7ee490 | 438 | |
2b8a912e | 439 | next_write_location = hv_copyto_ringbuffer(outring_info, |
fc8c72eb HZ |
440 | next_write_location, |
441 | &prev_indices, | |
b219b3f7 | 442 | sizeof(u64)); |
3e7ee490 | 443 | |
98fa8cf4 | 444 | /* Issue a full memory barrier before updating the write index */ |
35848f68 | 445 | mb(); |
3e7ee490 | 446 | |
454f18a9 | 447 | /* Now, update the write location */ |
2b8a912e | 448 | hv_set_next_write_location(outring_info, next_write_location); |
3e7ee490 | 449 | |
3e7ee490 | 450 | |
fc8c72eb | 451 | spin_unlock_irqrestore(&outring_info->ring_lock, flags); |
98fa8cf4 S |
452 | |
453 | *signal = hv_need_to_signal(old_write, outring_info); | |
3e7ee490 HJ |
454 | return 0; |
455 | } | |
456 | ||
457 | ||
b2a5a585 S |
458 | /* |
459 | * | |
460 | * hv_ringbuffer_peek() | |
461 | * | |
462 | * Read without advancing the read index | |
463 | * | |
464 | */ | |
a89186c2 | 465 | int hv_ringbuffer_peek(struct hv_ring_buffer_info *Inring_info, |
fc8c72eb | 466 | void *Buffer, u32 buflen) |
3e7ee490 | 467 | { |
fc8c72eb HZ |
468 | u32 bytes_avail_towrite; |
469 | u32 bytes_avail_toread; | |
470 | u32 next_read_location = 0; | |
a98f96ee | 471 | unsigned long flags; |
3e7ee490 | 472 | |
fc8c72eb | 473 | spin_lock_irqsave(&Inring_info->ring_lock, flags); |
3e7ee490 | 474 | |
2b8a912e | 475 | hv_get_ringbuffer_availbytes(Inring_info, |
fc8c72eb HZ |
476 | &bytes_avail_toread, |
477 | &bytes_avail_towrite); | |
3e7ee490 | 478 | |
454f18a9 | 479 | /* Make sure there is something to read */ |
fc8c72eb | 480 | if (bytes_avail_toread < buflen) { |
3e7ee490 | 481 | |
fc8c72eb | 482 | spin_unlock_irqrestore(&Inring_info->ring_lock, flags); |
3e7ee490 | 483 | |
d2598f01 | 484 | return -EAGAIN; |
3e7ee490 HJ |
485 | } |
486 | ||
454f18a9 | 487 | /* Convert to byte offset */ |
2b8a912e | 488 | next_read_location = hv_get_next_read_location(Inring_info); |
3e7ee490 | 489 | |
2b8a912e | 490 | next_read_location = hv_copyfrom_ringbuffer(Inring_info, |
4408f531 | 491 | Buffer, |
fc8c72eb HZ |
492 | buflen, |
493 | next_read_location); | |
3e7ee490 | 494 | |
fc8c72eb | 495 | spin_unlock_irqrestore(&Inring_info->ring_lock, flags); |
3e7ee490 HJ |
496 | |
497 | return 0; | |
498 | } | |
499 | ||
500 | ||
b2a5a585 S |
501 | /* |
502 | * | |
503 | * hv_ringbuffer_read() | |
504 | * | |
505 | * Read and advance the read index | |
506 | * | |
507 | */ | |
38397c8a | 508 | int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, void *buffer, |
c2b8e520 | 509 | u32 buflen, u32 offset, bool *signal) |
3e7ee490 | 510 | { |
fc8c72eb HZ |
511 | u32 bytes_avail_towrite; |
512 | u32 bytes_avail_toread; | |
513 | u32 next_read_location = 0; | |
514 | u64 prev_indices = 0; | |
a98f96ee | 515 | unsigned long flags; |
c2b8e520 | 516 | u32 old_read; |
3e7ee490 | 517 | |
fc8c72eb | 518 | if (buflen <= 0) |
a16e1485 | 519 | return -EINVAL; |
3e7ee490 | 520 | |
fc8c72eb | 521 | spin_lock_irqsave(&inring_info->ring_lock, flags); |
3e7ee490 | 522 | |
2b8a912e | 523 | hv_get_ringbuffer_availbytes(inring_info, |
fc8c72eb HZ |
524 | &bytes_avail_toread, |
525 | &bytes_avail_towrite); | |
3e7ee490 | 526 | |
c2b8e520 S |
527 | old_read = bytes_avail_toread; |
528 | ||
454f18a9 | 529 | /* Make sure there is something to read */ |
fc8c72eb | 530 | if (bytes_avail_toread < buflen) { |
fc8c72eb | 531 | spin_unlock_irqrestore(&inring_info->ring_lock, flags); |
3e7ee490 | 532 | |
d2598f01 | 533 | return -EAGAIN; |
3e7ee490 HJ |
534 | } |
535 | ||
1ac58644 | 536 | next_read_location = |
2b8a912e | 537 | hv_get_next_readlocation_withoffset(inring_info, offset); |
3e7ee490 | 538 | |
2b8a912e | 539 | next_read_location = hv_copyfrom_ringbuffer(inring_info, |
fc8c72eb HZ |
540 | buffer, |
541 | buflen, | |
542 | next_read_location); | |
3e7ee490 | 543 | |
2b8a912e | 544 | next_read_location = hv_copyfrom_ringbuffer(inring_info, |
fc8c72eb | 545 | &prev_indices, |
4408f531 | 546 | sizeof(u64), |
fc8c72eb | 547 | next_read_location); |
3e7ee490 | 548 | |
454f18a9 | 549 | /* Make sure all reads are done before we update the read index since */ |
4408f531 B |
550 | /* the writer may start writing to the read area once the read index */ |
551 | /*is updated */ | |
35848f68 | 552 | mb(); |
3e7ee490 | 553 | |
454f18a9 | 554 | /* Update the read index */ |
2b8a912e | 555 | hv_set_next_read_location(inring_info, next_read_location); |
3e7ee490 | 556 | |
fc8c72eb | 557 | spin_unlock_irqrestore(&inring_info->ring_lock, flags); |
3e7ee490 | 558 | |
c2b8e520 S |
559 | *signal = hv_need_to_signal_on_read(old_read, inring_info); |
560 | ||
3e7ee490 HJ |
561 | return 0; |
562 | } |