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> |
011a7c3c | 29 | #include <linux/uio.h> |
3f335ea2 | 30 | |
0f2a6619 | 31 | #include "hyperv_vmbus.h" |
3e7ee490 | 32 | |
6fdf3b21 S |
33 | void hv_begin_read(struct hv_ring_buffer_info *rbi) |
34 | { | |
35 | rbi->ring_buffer->interrupt_mask = 1; | |
35848f68 | 36 | mb(); |
6fdf3b21 S |
37 | } |
38 | ||
39 | u32 hv_end_read(struct hv_ring_buffer_info *rbi) | |
40 | { | |
41 | u32 read; | |
42 | u32 write; | |
43 | ||
44 | rbi->ring_buffer->interrupt_mask = 0; | |
35848f68 | 45 | mb(); |
6fdf3b21 S |
46 | |
47 | /* | |
48 | * Now check to see if the ring buffer is still empty. | |
49 | * If it is not, we raced and we need to process new | |
50 | * incoming messages. | |
51 | */ | |
52 | hv_get_ringbuffer_availbytes(rbi, &read, &write); | |
53 | ||
54 | return read; | |
55 | } | |
56 | ||
98fa8cf4 S |
57 | /* |
58 | * When we write to the ring buffer, check if the host needs to | |
59 | * be signaled. Here is the details of this protocol: | |
60 | * | |
61 | * 1. The host guarantees that while it is draining the | |
62 | * ring buffer, it will set the interrupt_mask to | |
63 | * indicate it does not need to be interrupted when | |
64 | * new data is placed. | |
65 | * | |
66 | * 2. The host guarantees that it will completely drain | |
67 | * the ring buffer before exiting the read loop. Further, | |
68 | * once the ring buffer is empty, it will clear the | |
69 | * interrupt_mask and re-check to see if new data has | |
70 | * arrived. | |
71 | */ | |
72 | ||
73 | static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi) | |
74 | { | |
35848f68 | 75 | mb(); |
98fa8cf4 S |
76 | if (rbi->ring_buffer->interrupt_mask) |
77 | return false; | |
78 | ||
e91e84fa JW |
79 | /* check interrupt_mask before read_index */ |
80 | rmb(); | |
98fa8cf4 S |
81 | /* |
82 | * This is the only case we need to signal when the | |
83 | * ring transitions from being empty to non-empty. | |
84 | */ | |
85 | if (old_write == rbi->ring_buffer->read_index) | |
86 | return true; | |
87 | ||
88 | return false; | |
89 | } | |
90 | ||
c2b8e520 S |
91 | /* |
92 | * To optimize the flow management on the send-side, | |
93 | * when the sender is blocked because of lack of | |
94 | * sufficient space in the ring buffer, potential the | |
95 | * consumer of the ring buffer can signal the producer. | |
96 | * This is controlled by the following parameters: | |
97 | * | |
98 | * 1. pending_send_sz: This is the size in bytes that the | |
99 | * producer is trying to send. | |
100 | * 2. The feature bit feat_pending_send_sz set to indicate if | |
101 | * the consumer of the ring will signal when the ring | |
102 | * state transitions from being full to a state where | |
103 | * there is room for the producer to send the pending packet. | |
104 | */ | |
105 | ||
a5cca686 CO |
106 | static bool hv_need_to_signal_on_read(u32 prev_write_sz, |
107 | struct hv_ring_buffer_info *rbi) | |
c2b8e520 | 108 | { |
c2b8e520 S |
109 | u32 cur_write_sz; |
110 | u32 r_size; | |
111 | u32 write_loc = rbi->ring_buffer->write_index; | |
112 | u32 read_loc = rbi->ring_buffer->read_index; | |
113 | u32 pending_sz = rbi->ring_buffer->pending_send_sz; | |
114 | ||
115 | /* | |
116 | * If the other end is not blocked on write don't bother. | |
117 | */ | |
118 | if (pending_sz == 0) | |
119 | return false; | |
120 | ||
121 | r_size = rbi->ring_datasize; | |
122 | cur_write_sz = write_loc >= read_loc ? r_size - (write_loc - read_loc) : | |
123 | read_loc - write_loc; | |
124 | ||
c2b8e520 S |
125 | if ((prev_write_sz < pending_sz) && (cur_write_sz >= pending_sz)) |
126 | return true; | |
127 | ||
128 | return false; | |
129 | } | |
3e7ee490 | 130 | |
b2a5a585 S |
131 | /* |
132 | * hv_get_next_write_location() | |
133 | * | |
134 | * Get the next write location for the specified ring buffer | |
135 | * | |
136 | */ | |
4d643114 | 137 | static inline u32 |
2b8a912e | 138 | hv_get_next_write_location(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 139 | { |
fc8c72eb | 140 | u32 next = ring_info->ring_buffer->write_index; |
3e7ee490 | 141 | |
3e7ee490 HJ |
142 | return next; |
143 | } | |
144 | ||
b2a5a585 S |
145 | /* |
146 | * hv_set_next_write_location() | |
147 | * | |
148 | * Set the next write location for the specified ring buffer | |
149 | * | |
150 | */ | |
3e7ee490 | 151 | static inline void |
2b8a912e | 152 | hv_set_next_write_location(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 153 | u32 next_write_location) |
3e7ee490 | 154 | { |
fc8c72eb | 155 | ring_info->ring_buffer->write_index = next_write_location; |
3e7ee490 HJ |
156 | } |
157 | ||
b2a5a585 S |
158 | /* |
159 | * hv_get_next_read_location() | |
160 | * | |
161 | * Get the next read location for the specified ring buffer | |
162 | */ | |
4d643114 | 163 | static inline u32 |
2b8a912e | 164 | hv_get_next_read_location(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 165 | { |
fc8c72eb | 166 | u32 next = ring_info->ring_buffer->read_index; |
3e7ee490 | 167 | |
3e7ee490 HJ |
168 | return next; |
169 | } | |
170 | ||
b2a5a585 S |
171 | /* |
172 | * hv_get_next_readlocation_withoffset() | |
173 | * | |
174 | * Get the next read location + offset for the specified ring buffer. | |
175 | * This allows the caller to skip | |
176 | */ | |
4d643114 | 177 | static inline u32 |
2b8a912e | 178 | hv_get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info, |
1ac58644 | 179 | u32 offset) |
3e7ee490 | 180 | { |
fc8c72eb | 181 | u32 next = ring_info->ring_buffer->read_index; |
3e7ee490 | 182 | |
fc8c72eb HZ |
183 | next += offset; |
184 | next %= ring_info->ring_datasize; | |
3e7ee490 HJ |
185 | |
186 | return next; | |
187 | } | |
188 | ||
b2a5a585 S |
189 | /* |
190 | * | |
191 | * hv_set_next_read_location() | |
192 | * | |
193 | * Set the next read location for the specified ring buffer | |
194 | * | |
195 | */ | |
3e7ee490 | 196 | static inline void |
2b8a912e | 197 | hv_set_next_read_location(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 198 | u32 next_read_location) |
3e7ee490 | 199 | { |
fc8c72eb | 200 | ring_info->ring_buffer->read_index = next_read_location; |
3e7ee490 HJ |
201 | } |
202 | ||
203 | ||
b2a5a585 S |
204 | /* |
205 | * | |
206 | * hv_get_ring_buffer() | |
207 | * | |
208 | * Get the start of the ring buffer | |
209 | */ | |
8282c400 | 210 | static inline void * |
2b8a912e | 211 | hv_get_ring_buffer(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 212 | { |
fc8c72eb | 213 | return (void *)ring_info->ring_buffer->buffer; |
3e7ee490 HJ |
214 | } |
215 | ||
216 | ||
b2a5a585 S |
217 | /* |
218 | * | |
219 | * hv_get_ring_buffersize() | |
220 | * | |
221 | * Get the size of the ring buffer | |
222 | */ | |
4d643114 | 223 | static inline u32 |
2b8a912e | 224 | hv_get_ring_buffersize(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 225 | { |
fc8c72eb | 226 | return ring_info->ring_datasize; |
3e7ee490 HJ |
227 | } |
228 | ||
b2a5a585 S |
229 | /* |
230 | * | |
231 | * hv_get_ring_bufferindices() | |
232 | * | |
233 | * Get the read and write indices as u64 of the specified ring buffer | |
234 | * | |
235 | */ | |
59471438 | 236 | static inline u64 |
2b8a912e | 237 | hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 238 | { |
fc8c72eb | 239 | return (u64)ring_info->ring_buffer->write_index << 32; |
3e7ee490 HJ |
240 | } |
241 | ||
8f1136ae S |
242 | /* |
243 | * | |
244 | * hv_copyfrom_ringbuffer() | |
245 | * | |
246 | * Helper routine to copy to source from ring buffer. | |
247 | * Assume there is enough room. Handles wrap-around in src case only!! | |
248 | * | |
249 | */ | |
250 | static u32 hv_copyfrom_ringbuffer( | |
251 | struct hv_ring_buffer_info *ring_info, | |
252 | void *dest, | |
253 | u32 destlen, | |
254 | u32 start_read_offset) | |
255 | { | |
256 | void *ring_buffer = hv_get_ring_buffer(ring_info); | |
257 | u32 ring_buffer_size = hv_get_ring_buffersize(ring_info); | |
258 | ||
259 | u32 frag_len; | |
260 | ||
261 | /* wrap-around detected at the src */ | |
262 | if (destlen > ring_buffer_size - start_read_offset) { | |
263 | frag_len = ring_buffer_size - start_read_offset; | |
264 | ||
265 | memcpy(dest, ring_buffer + start_read_offset, frag_len); | |
266 | memcpy(dest + frag_len, ring_buffer, destlen - frag_len); | |
267 | } else | |
268 | ||
269 | memcpy(dest, ring_buffer + start_read_offset, destlen); | |
270 | ||
271 | ||
272 | start_read_offset += destlen; | |
273 | start_read_offset %= ring_buffer_size; | |
274 | ||
275 | return start_read_offset; | |
276 | } | |
277 | ||
278 | ||
7581578d S |
279 | /* |
280 | * | |
281 | * hv_copyto_ringbuffer() | |
282 | * | |
283 | * Helper routine to copy from source to ring buffer. | |
284 | * Assume there is enough room. Handles wrap-around in dest case only!! | |
285 | * | |
286 | */ | |
287 | static u32 hv_copyto_ringbuffer( | |
fc8c72eb HZ |
288 | struct hv_ring_buffer_info *ring_info, |
289 | u32 start_write_offset, | |
290 | void *src, | |
7581578d S |
291 | u32 srclen) |
292 | { | |
293 | void *ring_buffer = hv_get_ring_buffer(ring_info); | |
294 | u32 ring_buffer_size = hv_get_ring_buffersize(ring_info); | |
295 | u32 frag_len; | |
296 | ||
297 | /* wrap-around detected! */ | |
298 | if (srclen > ring_buffer_size - start_write_offset) { | |
299 | frag_len = ring_buffer_size - start_write_offset; | |
300 | memcpy(ring_buffer + start_write_offset, src, frag_len); | |
301 | memcpy(ring_buffer, src + frag_len, srclen - frag_len); | |
302 | } else | |
303 | memcpy(ring_buffer + start_write_offset, src, srclen); | |
3e7ee490 | 304 | |
7581578d S |
305 | start_write_offset += srclen; |
306 | start_write_offset %= ring_buffer_size; | |
307 | ||
308 | return start_write_offset; | |
309 | } | |
3e7ee490 | 310 | |
b2a5a585 S |
311 | /* |
312 | * | |
313 | * hv_ringbuffer_get_debuginfo() | |
314 | * | |
315 | * Get various debug metrics for the specified ring buffer | |
316 | * | |
317 | */ | |
a75b61d5 | 318 | void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info, |
80682b7a | 319 | struct hv_ring_buffer_debug_info *debug_info) |
3e7ee490 | 320 | { |
fc8c72eb HZ |
321 | u32 bytes_avail_towrite; |
322 | u32 bytes_avail_toread; | |
3e7ee490 | 323 | |
fc8c72eb | 324 | if (ring_info->ring_buffer) { |
2b8a912e | 325 | hv_get_ringbuffer_availbytes(ring_info, |
fc8c72eb HZ |
326 | &bytes_avail_toread, |
327 | &bytes_avail_towrite); | |
3e7ee490 | 328 | |
fc8c72eb HZ |
329 | debug_info->bytes_avail_toread = bytes_avail_toread; |
330 | debug_info->bytes_avail_towrite = bytes_avail_towrite; | |
82f8bd40 | 331 | debug_info->current_read_index = |
fc8c72eb | 332 | ring_info->ring_buffer->read_index; |
82f8bd40 | 333 | debug_info->current_write_index = |
fc8c72eb | 334 | ring_info->ring_buffer->write_index; |
82f8bd40 | 335 | debug_info->current_interrupt_mask = |
fc8c72eb | 336 | ring_info->ring_buffer->interrupt_mask; |
3e7ee490 HJ |
337 | } |
338 | } | |
339 | ||
b2a5a585 S |
340 | /* |
341 | * | |
342 | * hv_ringbuffer_init() | |
343 | * | |
344 | *Initialize the ring buffer | |
345 | * | |
346 | */ | |
72a95cbc | 347 | int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 348 | void *buffer, u32 buflen) |
3e7ee490 | 349 | { |
4a1b3acc | 350 | if (sizeof(struct hv_ring_buffer) != PAGE_SIZE) |
3324fb40 | 351 | return -EINVAL; |
3e7ee490 | 352 | |
fc8c72eb | 353 | memset(ring_info, 0, sizeof(struct hv_ring_buffer_info)); |
3e7ee490 | 354 | |
fc8c72eb HZ |
355 | ring_info->ring_buffer = (struct hv_ring_buffer *)buffer; |
356 | ring_info->ring_buffer->read_index = | |
357 | ring_info->ring_buffer->write_index = 0; | |
3e7ee490 | 358 | |
046c7911 S |
359 | /* |
360 | * Set the feature bit for enabling flow control. | |
361 | */ | |
362 | ring_info->ring_buffer->feature_bits.value = 1; | |
363 | ||
fc8c72eb HZ |
364 | ring_info->ring_size = buflen; |
365 | ring_info->ring_datasize = buflen - sizeof(struct hv_ring_buffer); | |
3e7ee490 | 366 | |
fc8c72eb | 367 | spin_lock_init(&ring_info->ring_lock); |
3e7ee490 HJ |
368 | |
369 | return 0; | |
370 | } | |
371 | ||
b2a5a585 S |
372 | /* |
373 | * | |
374 | * hv_ringbuffer_cleanup() | |
375 | * | |
376 | * Cleanup the ring buffer | |
377 | * | |
378 | */ | |
2dba688b | 379 | void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 380 | { |
3e7ee490 HJ |
381 | } |
382 | ||
b2a5a585 S |
383 | /* |
384 | * | |
385 | * hv_ringbuffer_write() | |
386 | * | |
387 | * Write to the ring buffer | |
388 | * | |
389 | */ | |
633c4dce | 390 | int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info, |
011a7c3c | 391 | struct kvec *kv_list, u32 kv_count, bool *signal) |
3e7ee490 | 392 | { |
4408f531 | 393 | int i = 0; |
fc8c72eb HZ |
394 | u32 bytes_avail_towrite; |
395 | u32 bytes_avail_toread; | |
396 | u32 totalbytes_towrite = 0; | |
3e7ee490 | 397 | |
66a60543 | 398 | u32 next_write_location; |
98fa8cf4 | 399 | u32 old_write; |
fc8c72eb | 400 | u64 prev_indices = 0; |
a98f96ee | 401 | unsigned long flags; |
3e7ee490 | 402 | |
011a7c3c S |
403 | for (i = 0; i < kv_count; i++) |
404 | totalbytes_towrite += kv_list[i].iov_len; | |
3e7ee490 | 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 | ||
011a7c3c | 428 | for (i = 0; i < kv_count; i++) { |
2b8a912e | 429 | next_write_location = hv_copyto_ringbuffer(outring_info, |
fc8c72eb | 430 | next_write_location, |
011a7c3c S |
431 | kv_list[i].iov_base, |
432 | kv_list[i].iov_len); | |
3e7ee490 HJ |
433 | } |
434 | ||
454f18a9 | 435 | /* Set previous packet start */ |
2b8a912e | 436 | prev_indices = hv_get_ring_bufferindices(outring_info); |
3e7ee490 | 437 | |
2b8a912e | 438 | next_write_location = hv_copyto_ringbuffer(outring_info, |
fc8c72eb HZ |
439 | next_write_location, |
440 | &prev_indices, | |
b219b3f7 | 441 | sizeof(u64)); |
3e7ee490 | 442 | |
98fa8cf4 | 443 | /* Issue a full memory barrier before updating the write index */ |
35848f68 | 444 | mb(); |
3e7ee490 | 445 | |
454f18a9 | 446 | /* Now, update the write location */ |
2b8a912e | 447 | hv_set_next_write_location(outring_info, next_write_location); |
3e7ee490 | 448 | |
3e7ee490 | 449 | |
fc8c72eb | 450 | spin_unlock_irqrestore(&outring_info->ring_lock, flags); |
98fa8cf4 S |
451 | |
452 | *signal = hv_need_to_signal(old_write, outring_info); | |
3e7ee490 HJ |
453 | return 0; |
454 | } | |
455 | ||
456 | ||
b2a5a585 S |
457 | /* |
458 | * | |
459 | * hv_ringbuffer_peek() | |
460 | * | |
461 | * Read without advancing the read index | |
462 | * | |
463 | */ | |
a89186c2 | 464 | int hv_ringbuffer_peek(struct hv_ring_buffer_info *Inring_info, |
fc8c72eb | 465 | void *Buffer, u32 buflen) |
3e7ee490 | 466 | { |
fc8c72eb HZ |
467 | u32 bytes_avail_towrite; |
468 | u32 bytes_avail_toread; | |
469 | u32 next_read_location = 0; | |
a98f96ee | 470 | unsigned long flags; |
3e7ee490 | 471 | |
fc8c72eb | 472 | spin_lock_irqsave(&Inring_info->ring_lock, flags); |
3e7ee490 | 473 | |
2b8a912e | 474 | hv_get_ringbuffer_availbytes(Inring_info, |
fc8c72eb HZ |
475 | &bytes_avail_toread, |
476 | &bytes_avail_towrite); | |
3e7ee490 | 477 | |
454f18a9 | 478 | /* Make sure there is something to read */ |
fc8c72eb | 479 | if (bytes_avail_toread < buflen) { |
3e7ee490 | 480 | |
fc8c72eb | 481 | spin_unlock_irqrestore(&Inring_info->ring_lock, flags); |
3e7ee490 | 482 | |
d2598f01 | 483 | return -EAGAIN; |
3e7ee490 HJ |
484 | } |
485 | ||
454f18a9 | 486 | /* Convert to byte offset */ |
2b8a912e | 487 | next_read_location = hv_get_next_read_location(Inring_info); |
3e7ee490 | 488 | |
2b8a912e | 489 | next_read_location = hv_copyfrom_ringbuffer(Inring_info, |
4408f531 | 490 | Buffer, |
fc8c72eb HZ |
491 | buflen, |
492 | next_read_location); | |
3e7ee490 | 493 | |
fc8c72eb | 494 | spin_unlock_irqrestore(&Inring_info->ring_lock, flags); |
3e7ee490 HJ |
495 | |
496 | return 0; | |
497 | } | |
498 | ||
499 | ||
b2a5a585 S |
500 | /* |
501 | * | |
502 | * hv_ringbuffer_read() | |
503 | * | |
504 | * Read and advance the read index | |
505 | * | |
506 | */ | |
38397c8a | 507 | int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, void *buffer, |
c2b8e520 | 508 | u32 buflen, u32 offset, bool *signal) |
3e7ee490 | 509 | { |
fc8c72eb HZ |
510 | u32 bytes_avail_towrite; |
511 | u32 bytes_avail_toread; | |
512 | u32 next_read_location = 0; | |
513 | u64 prev_indices = 0; | |
a98f96ee | 514 | unsigned long flags; |
3e7ee490 | 515 | |
fc8c72eb | 516 | if (buflen <= 0) |
a16e1485 | 517 | return -EINVAL; |
3e7ee490 | 518 | |
fc8c72eb | 519 | spin_lock_irqsave(&inring_info->ring_lock, flags); |
3e7ee490 | 520 | |
2b8a912e | 521 | hv_get_ringbuffer_availbytes(inring_info, |
fc8c72eb HZ |
522 | &bytes_avail_toread, |
523 | &bytes_avail_towrite); | |
3e7ee490 | 524 | |
454f18a9 | 525 | /* Make sure there is something to read */ |
fc8c72eb | 526 | if (bytes_avail_toread < buflen) { |
fc8c72eb | 527 | spin_unlock_irqrestore(&inring_info->ring_lock, flags); |
3e7ee490 | 528 | |
d2598f01 | 529 | return -EAGAIN; |
3e7ee490 HJ |
530 | } |
531 | ||
1ac58644 | 532 | next_read_location = |
2b8a912e | 533 | hv_get_next_readlocation_withoffset(inring_info, offset); |
3e7ee490 | 534 | |
2b8a912e | 535 | next_read_location = hv_copyfrom_ringbuffer(inring_info, |
fc8c72eb HZ |
536 | buffer, |
537 | buflen, | |
538 | next_read_location); | |
3e7ee490 | 539 | |
2b8a912e | 540 | next_read_location = hv_copyfrom_ringbuffer(inring_info, |
fc8c72eb | 541 | &prev_indices, |
4408f531 | 542 | sizeof(u64), |
fc8c72eb | 543 | next_read_location); |
3e7ee490 | 544 | |
454f18a9 | 545 | /* Make sure all reads are done before we update the read index since */ |
4408f531 B |
546 | /* the writer may start writing to the read area once the read index */ |
547 | /*is updated */ | |
35848f68 | 548 | mb(); |
3e7ee490 | 549 | |
454f18a9 | 550 | /* Update the read index */ |
2b8a912e | 551 | hv_set_next_read_location(inring_info, next_read_location); |
3e7ee490 | 552 | |
fc8c72eb | 553 | spin_unlock_irqrestore(&inring_info->ring_lock, flags); |
3e7ee490 | 554 | |
a5cca686 | 555 | *signal = hv_need_to_signal_on_read(bytes_avail_towrite, inring_info); |
c2b8e520 | 556 | |
3e7ee490 HJ |
557 | return 0; |
558 | } |