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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; | |
35 | smp_mb(); | |
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; | |
44 | smp_mb(); | |
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 | { | |
74 | if (rbi->ring_buffer->interrupt_mask) | |
75 | return false; | |
76 | ||
77 | /* | |
78 | * This is the only case we need to signal when the | |
79 | * ring transitions from being empty to non-empty. | |
80 | */ | |
81 | if (old_write == rbi->ring_buffer->read_index) | |
82 | return true; | |
83 | ||
84 | return false; | |
85 | } | |
86 | ||
c2b8e520 S |
87 | /* |
88 | * To optimize the flow management on the send-side, | |
89 | * when the sender is blocked because of lack of | |
90 | * sufficient space in the ring buffer, potential the | |
91 | * consumer of the ring buffer can signal the producer. | |
92 | * This is controlled by the following parameters: | |
93 | * | |
94 | * 1. pending_send_sz: This is the size in bytes that the | |
95 | * producer is trying to send. | |
96 | * 2. The feature bit feat_pending_send_sz set to indicate if | |
97 | * the consumer of the ring will signal when the ring | |
98 | * state transitions from being full to a state where | |
99 | * there is room for the producer to send the pending packet. | |
100 | */ | |
101 | ||
102 | static bool hv_need_to_signal_on_read(u32 old_rd, | |
103 | struct hv_ring_buffer_info *rbi) | |
104 | { | |
105 | u32 prev_write_sz; | |
106 | u32 cur_write_sz; | |
107 | u32 r_size; | |
108 | u32 write_loc = rbi->ring_buffer->write_index; | |
109 | u32 read_loc = rbi->ring_buffer->read_index; | |
110 | u32 pending_sz = rbi->ring_buffer->pending_send_sz; | |
111 | ||
112 | /* | |
113 | * If the other end is not blocked on write don't bother. | |
114 | */ | |
115 | if (pending_sz == 0) | |
116 | return false; | |
117 | ||
118 | r_size = rbi->ring_datasize; | |
119 | cur_write_sz = write_loc >= read_loc ? r_size - (write_loc - read_loc) : | |
120 | read_loc - write_loc; | |
121 | ||
122 | prev_write_sz = write_loc >= old_rd ? r_size - (write_loc - old_rd) : | |
123 | old_rd - write_loc; | |
124 | ||
125 | ||
126 | if ((prev_write_sz < pending_sz) && (cur_write_sz >= pending_sz)) | |
127 | return true; | |
128 | ||
129 | return false; | |
130 | } | |
3e7ee490 | 131 | |
b2a5a585 S |
132 | /* |
133 | * hv_get_next_write_location() | |
134 | * | |
135 | * Get the next write location for the specified ring buffer | |
136 | * | |
137 | */ | |
4d643114 | 138 | static inline u32 |
2b8a912e | 139 | hv_get_next_write_location(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 140 | { |
fc8c72eb | 141 | u32 next = ring_info->ring_buffer->write_index; |
3e7ee490 | 142 | |
3e7ee490 HJ |
143 | return next; |
144 | } | |
145 | ||
b2a5a585 S |
146 | /* |
147 | * hv_set_next_write_location() | |
148 | * | |
149 | * Set the next write location for the specified ring buffer | |
150 | * | |
151 | */ | |
3e7ee490 | 152 | static inline void |
2b8a912e | 153 | hv_set_next_write_location(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 154 | u32 next_write_location) |
3e7ee490 | 155 | { |
fc8c72eb | 156 | ring_info->ring_buffer->write_index = next_write_location; |
3e7ee490 HJ |
157 | } |
158 | ||
b2a5a585 S |
159 | /* |
160 | * hv_get_next_read_location() | |
161 | * | |
162 | * Get the next read location for the specified ring buffer | |
163 | */ | |
4d643114 | 164 | static inline u32 |
2b8a912e | 165 | hv_get_next_read_location(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 166 | { |
fc8c72eb | 167 | u32 next = ring_info->ring_buffer->read_index; |
3e7ee490 | 168 | |
3e7ee490 HJ |
169 | return next; |
170 | } | |
171 | ||
b2a5a585 S |
172 | /* |
173 | * hv_get_next_readlocation_withoffset() | |
174 | * | |
175 | * Get the next read location + offset for the specified ring buffer. | |
176 | * This allows the caller to skip | |
177 | */ | |
4d643114 | 178 | static inline u32 |
2b8a912e | 179 | hv_get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info, |
1ac58644 | 180 | u32 offset) |
3e7ee490 | 181 | { |
fc8c72eb | 182 | u32 next = ring_info->ring_buffer->read_index; |
3e7ee490 | 183 | |
fc8c72eb HZ |
184 | next += offset; |
185 | next %= ring_info->ring_datasize; | |
3e7ee490 HJ |
186 | |
187 | return next; | |
188 | } | |
189 | ||
b2a5a585 S |
190 | /* |
191 | * | |
192 | * hv_set_next_read_location() | |
193 | * | |
194 | * Set the next read location for the specified ring buffer | |
195 | * | |
196 | */ | |
3e7ee490 | 197 | static inline void |
2b8a912e | 198 | hv_set_next_read_location(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 199 | u32 next_read_location) |
3e7ee490 | 200 | { |
fc8c72eb | 201 | ring_info->ring_buffer->read_index = next_read_location; |
3e7ee490 HJ |
202 | } |
203 | ||
204 | ||
b2a5a585 S |
205 | /* |
206 | * | |
207 | * hv_get_ring_buffer() | |
208 | * | |
209 | * Get the start of the ring buffer | |
210 | */ | |
8282c400 | 211 | static inline void * |
2b8a912e | 212 | hv_get_ring_buffer(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 213 | { |
fc8c72eb | 214 | return (void *)ring_info->ring_buffer->buffer; |
3e7ee490 HJ |
215 | } |
216 | ||
217 | ||
b2a5a585 S |
218 | /* |
219 | * | |
220 | * hv_get_ring_buffersize() | |
221 | * | |
222 | * Get the size of the ring buffer | |
223 | */ | |
4d643114 | 224 | static inline u32 |
2b8a912e | 225 | hv_get_ring_buffersize(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 226 | { |
fc8c72eb | 227 | return ring_info->ring_datasize; |
3e7ee490 HJ |
228 | } |
229 | ||
b2a5a585 S |
230 | /* |
231 | * | |
232 | * hv_get_ring_bufferindices() | |
233 | * | |
234 | * Get the read and write indices as u64 of the specified ring buffer | |
235 | * | |
236 | */ | |
59471438 | 237 | static inline u64 |
2b8a912e | 238 | hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 239 | { |
fc8c72eb | 240 | return (u64)ring_info->ring_buffer->write_index << 32; |
3e7ee490 HJ |
241 | } |
242 | ||
8f1136ae S |
243 | /* |
244 | * | |
245 | * hv_copyfrom_ringbuffer() | |
246 | * | |
247 | * Helper routine to copy to source from ring buffer. | |
248 | * Assume there is enough room. Handles wrap-around in src case only!! | |
249 | * | |
250 | */ | |
251 | static u32 hv_copyfrom_ringbuffer( | |
252 | struct hv_ring_buffer_info *ring_info, | |
253 | void *dest, | |
254 | u32 destlen, | |
255 | u32 start_read_offset) | |
256 | { | |
257 | void *ring_buffer = hv_get_ring_buffer(ring_info); | |
258 | u32 ring_buffer_size = hv_get_ring_buffersize(ring_info); | |
259 | ||
260 | u32 frag_len; | |
261 | ||
262 | /* wrap-around detected at the src */ | |
263 | if (destlen > ring_buffer_size - start_read_offset) { | |
264 | frag_len = ring_buffer_size - start_read_offset; | |
265 | ||
266 | memcpy(dest, ring_buffer + start_read_offset, frag_len); | |
267 | memcpy(dest + frag_len, ring_buffer, destlen - frag_len); | |
268 | } else | |
269 | ||
270 | memcpy(dest, ring_buffer + start_read_offset, destlen); | |
271 | ||
272 | ||
273 | start_read_offset += destlen; | |
274 | start_read_offset %= ring_buffer_size; | |
275 | ||
276 | return start_read_offset; | |
277 | } | |
278 | ||
279 | ||
7581578d S |
280 | /* |
281 | * | |
282 | * hv_copyto_ringbuffer() | |
283 | * | |
284 | * Helper routine to copy from source to ring buffer. | |
285 | * Assume there is enough room. Handles wrap-around in dest case only!! | |
286 | * | |
287 | */ | |
288 | static u32 hv_copyto_ringbuffer( | |
fc8c72eb HZ |
289 | struct hv_ring_buffer_info *ring_info, |
290 | u32 start_write_offset, | |
291 | void *src, | |
7581578d S |
292 | u32 srclen) |
293 | { | |
294 | void *ring_buffer = hv_get_ring_buffer(ring_info); | |
295 | u32 ring_buffer_size = hv_get_ring_buffersize(ring_info); | |
296 | u32 frag_len; | |
297 | ||
298 | /* wrap-around detected! */ | |
299 | if (srclen > ring_buffer_size - start_write_offset) { | |
300 | frag_len = ring_buffer_size - start_write_offset; | |
301 | memcpy(ring_buffer + start_write_offset, src, frag_len); | |
302 | memcpy(ring_buffer, src + frag_len, srclen - frag_len); | |
303 | } else | |
304 | memcpy(ring_buffer + start_write_offset, src, srclen); | |
3e7ee490 | 305 | |
7581578d S |
306 | start_write_offset += srclen; |
307 | start_write_offset %= ring_buffer_size; | |
308 | ||
309 | return start_write_offset; | |
310 | } | |
3e7ee490 | 311 | |
b2a5a585 S |
312 | /* |
313 | * | |
314 | * hv_ringbuffer_get_debuginfo() | |
315 | * | |
316 | * Get various debug metrics for the specified ring buffer | |
317 | * | |
318 | */ | |
a75b61d5 | 319 | void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info, |
80682b7a | 320 | struct hv_ring_buffer_debug_info *debug_info) |
3e7ee490 | 321 | { |
fc8c72eb HZ |
322 | u32 bytes_avail_towrite; |
323 | u32 bytes_avail_toread; | |
3e7ee490 | 324 | |
fc8c72eb | 325 | if (ring_info->ring_buffer) { |
2b8a912e | 326 | hv_get_ringbuffer_availbytes(ring_info, |
fc8c72eb HZ |
327 | &bytes_avail_toread, |
328 | &bytes_avail_towrite); | |
3e7ee490 | 329 | |
fc8c72eb HZ |
330 | debug_info->bytes_avail_toread = bytes_avail_toread; |
331 | debug_info->bytes_avail_towrite = bytes_avail_towrite; | |
82f8bd40 | 332 | debug_info->current_read_index = |
fc8c72eb | 333 | ring_info->ring_buffer->read_index; |
82f8bd40 | 334 | debug_info->current_write_index = |
fc8c72eb | 335 | ring_info->ring_buffer->write_index; |
82f8bd40 | 336 | debug_info->current_interrupt_mask = |
fc8c72eb | 337 | ring_info->ring_buffer->interrupt_mask; |
3e7ee490 HJ |
338 | } |
339 | } | |
340 | ||
b2a5a585 S |
341 | /* |
342 | * | |
343 | * hv_ringbuffer_init() | |
344 | * | |
345 | *Initialize the ring buffer | |
346 | * | |
347 | */ | |
72a95cbc | 348 | int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 349 | void *buffer, u32 buflen) |
3e7ee490 | 350 | { |
4a1b3acc | 351 | if (sizeof(struct hv_ring_buffer) != PAGE_SIZE) |
3324fb40 | 352 | return -EINVAL; |
3e7ee490 | 353 | |
fc8c72eb | 354 | memset(ring_info, 0, sizeof(struct hv_ring_buffer_info)); |
3e7ee490 | 355 | |
fc8c72eb HZ |
356 | ring_info->ring_buffer = (struct hv_ring_buffer *)buffer; |
357 | ring_info->ring_buffer->read_index = | |
358 | ring_info->ring_buffer->write_index = 0; | |
3e7ee490 | 359 | |
fc8c72eb HZ |
360 | ring_info->ring_size = buflen; |
361 | ring_info->ring_datasize = buflen - sizeof(struct hv_ring_buffer); | |
3e7ee490 | 362 | |
fc8c72eb | 363 | spin_lock_init(&ring_info->ring_lock); |
3e7ee490 HJ |
364 | |
365 | return 0; | |
366 | } | |
367 | ||
b2a5a585 S |
368 | /* |
369 | * | |
370 | * hv_ringbuffer_cleanup() | |
371 | * | |
372 | * Cleanup the ring buffer | |
373 | * | |
374 | */ | |
2dba688b | 375 | void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 376 | { |
3e7ee490 HJ |
377 | } |
378 | ||
b2a5a585 S |
379 | /* |
380 | * | |
381 | * hv_ringbuffer_write() | |
382 | * | |
383 | * Write to the ring buffer | |
384 | * | |
385 | */ | |
633c4dce | 386 | int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info, |
98fa8cf4 | 387 | struct scatterlist *sglist, u32 sgcount, bool *signal) |
3e7ee490 | 388 | { |
4408f531 | 389 | int i = 0; |
fc8c72eb HZ |
390 | u32 bytes_avail_towrite; |
391 | u32 bytes_avail_toread; | |
392 | u32 totalbytes_towrite = 0; | |
3e7ee490 | 393 | |
b219b3f7 | 394 | struct scatterlist *sg; |
66a60543 | 395 | u32 next_write_location; |
98fa8cf4 | 396 | u32 old_write; |
fc8c72eb | 397 | u64 prev_indices = 0; |
a98f96ee | 398 | unsigned long flags; |
3e7ee490 | 399 | |
b219b3f7 | 400 | for_each_sg(sglist, sg, sgcount, i) |
3e7ee490 | 401 | { |
fc8c72eb | 402 | totalbytes_towrite += sg->length; |
3e7ee490 HJ |
403 | } |
404 | ||
fc8c72eb | 405 | totalbytes_towrite += sizeof(u64); |
3e7ee490 | 406 | |
fc8c72eb | 407 | spin_lock_irqsave(&outring_info->ring_lock, flags); |
3e7ee490 | 408 | |
2b8a912e | 409 | hv_get_ringbuffer_availbytes(outring_info, |
fc8c72eb HZ |
410 | &bytes_avail_toread, |
411 | &bytes_avail_towrite); | |
3e7ee490 | 412 | |
3e7ee490 | 413 | |
4408f531 B |
414 | /* If there is only room for the packet, assume it is full. */ |
415 | /* Otherwise, the next time around, we think the ring buffer */ | |
454f18a9 | 416 | /* is empty since the read index == write index */ |
fc8c72eb | 417 | if (bytes_avail_towrite <= totalbytes_towrite) { |
fc8c72eb | 418 | spin_unlock_irqrestore(&outring_info->ring_lock, flags); |
d2598f01 | 419 | return -EAGAIN; |
3e7ee490 HJ |
420 | } |
421 | ||
454f18a9 | 422 | /* Write to the ring buffer */ |
2b8a912e | 423 | next_write_location = hv_get_next_write_location(outring_info); |
3e7ee490 | 424 | |
98fa8cf4 S |
425 | old_write = next_write_location; |
426 | ||
b219b3f7 | 427 | for_each_sg(sglist, sg, sgcount, i) |
3e7ee490 | 428 | { |
2b8a912e | 429 | next_write_location = hv_copyto_ringbuffer(outring_info, |
fc8c72eb | 430 | next_write_location, |
b219b3f7 NP |
431 | sg_virt(sg), |
432 | sg->length); | |
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 S |
443 | /* Issue a full memory barrier before updating the write index */ |
444 | smp_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; |
c2b8e520 | 515 | u32 old_read; |
3e7ee490 | 516 | |
fc8c72eb | 517 | if (buflen <= 0) |
a16e1485 | 518 | return -EINVAL; |
3e7ee490 | 519 | |
fc8c72eb | 520 | spin_lock_irqsave(&inring_info->ring_lock, flags); |
3e7ee490 | 521 | |
2b8a912e | 522 | hv_get_ringbuffer_availbytes(inring_info, |
fc8c72eb HZ |
523 | &bytes_avail_toread, |
524 | &bytes_avail_towrite); | |
3e7ee490 | 525 | |
c2b8e520 S |
526 | old_read = bytes_avail_toread; |
527 | ||
454f18a9 | 528 | /* Make sure there is something to read */ |
fc8c72eb | 529 | if (bytes_avail_toread < buflen) { |
fc8c72eb | 530 | spin_unlock_irqrestore(&inring_info->ring_lock, flags); |
3e7ee490 | 531 | |
d2598f01 | 532 | return -EAGAIN; |
3e7ee490 HJ |
533 | } |
534 | ||
1ac58644 | 535 | next_read_location = |
2b8a912e | 536 | hv_get_next_readlocation_withoffset(inring_info, offset); |
3e7ee490 | 537 | |
2b8a912e | 538 | next_read_location = hv_copyfrom_ringbuffer(inring_info, |
fc8c72eb HZ |
539 | buffer, |
540 | buflen, | |
541 | next_read_location); | |
3e7ee490 | 542 | |
2b8a912e | 543 | next_read_location = hv_copyfrom_ringbuffer(inring_info, |
fc8c72eb | 544 | &prev_indices, |
4408f531 | 545 | sizeof(u64), |
fc8c72eb | 546 | next_read_location); |
3e7ee490 | 547 | |
454f18a9 | 548 | /* Make sure all reads are done before we update the read index since */ |
4408f531 B |
549 | /* the writer may start writing to the read area once the read index */ |
550 | /*is updated */ | |
ef0d5b23 | 551 | smp_mb(); |
3e7ee490 | 552 | |
454f18a9 | 553 | /* Update the read index */ |
2b8a912e | 554 | hv_set_next_read_location(inring_info, next_read_location); |
3e7ee490 | 555 | |
fc8c72eb | 556 | spin_unlock_irqrestore(&inring_info->ring_lock, flags); |
3e7ee490 | 557 | |
c2b8e520 S |
558 | *signal = hv_need_to_signal_on_read(old_read, inring_info); |
559 | ||
3e7ee490 HJ |
560 | return 0; |
561 | } |