blob: 15db66b74141cb6c92a180197c4261c77a2eeaa3 [file] [log] [blame]
Hank Janssen3e7ee492009-07-13 16:02:34 -07001/*
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>
K. Y. Srinivasanb2a5a582011-05-10 07:55:30 -070021 * K. Y. Srinivasan <kys@microsoft.com>
Hank Janssen3e7ee492009-07-13 16:02:34 -070022 *
23 */
Hank Janssen0a466182011-03-29 13:58:47 -070024#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
Hank Janssen3e7ee492009-07-13 16:02:34 -070025
Greg Kroah-Hartmana0086dc2009-08-17 17:22:08 -070026#include <linux/kernel.h>
27#include <linux/mm.h>
Greg Kroah-Hartman46a97192011-10-04 12:29:52 -070028#include <linux/hyperv.h>
K. Y. Srinivasan011a7c32014-02-01 19:02:20 -080029#include <linux/uio.h>
K. Y. Srinivasan3f335ea2011-05-12 19:34:15 -070030
K. Y. Srinivasan0f2a6612011-05-12 19:34:28 -070031#include "hyperv_vmbus.h"
Hank Janssen3e7ee492009-07-13 16:02:34 -070032
K. Y. Srinivasan6fdf3b22012-12-01 06:46:32 -080033void hv_begin_read(struct hv_ring_buffer_info *rbi)
34{
35 rbi->ring_buffer->interrupt_mask = 1;
Jason Wang35848f62013-06-18 13:04:23 +080036 mb();
K. Y. Srinivasan6fdf3b22012-12-01 06:46:32 -080037}
38
39u32 hv_end_read(struct hv_ring_buffer_info *rbi)
40{
41 u32 read;
42 u32 write;
43
44 rbi->ring_buffer->interrupt_mask = 0;
Jason Wang35848f62013-06-18 13:04:23 +080045 mb();
K. Y. Srinivasan6fdf3b22012-12-01 06:46:32 -080046
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
K. Y. Srinivasan98fa8cf2012-12-01 06:46:36 -080057/*
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
73static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi)
74{
Jason Wang35848f62013-06-18 13:04:23 +080075 mb();
K. Y. Srinivasan98fa8cf2012-12-01 06:46:36 -080076 if (rbi->ring_buffer->interrupt_mask)
77 return false;
78
Jason Wange91e84f2013-06-20 12:58:57 +080079 /* check interrupt_mask before read_index */
80 rmb();
K. Y. Srinivasan98fa8cf2012-12-01 06:46:36 -080081 /*
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
K. Y. Srinivasanc2b8e522012-12-01 06:46:57 -080091/*
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
106static bool hv_need_to_signal_on_read(u32 old_rd,
107 struct hv_ring_buffer_info *rbi)
108{
109 u32 prev_write_sz;
110 u32 cur_write_sz;
111 u32 r_size;
112 u32 write_loc = rbi->ring_buffer->write_index;
113 u32 read_loc = rbi->ring_buffer->read_index;
114 u32 pending_sz = rbi->ring_buffer->pending_send_sz;
115
116 /*
117 * If the other end is not blocked on write don't bother.
118 */
119 if (pending_sz == 0)
120 return false;
121
122 r_size = rbi->ring_datasize;
123 cur_write_sz = write_loc >= read_loc ? r_size - (write_loc - read_loc) :
124 read_loc - write_loc;
125
126 prev_write_sz = write_loc >= old_rd ? r_size - (write_loc - old_rd) :
127 old_rd - write_loc;
128
129
130 if ((prev_write_sz < pending_sz) && (cur_write_sz >= pending_sz))
131 return true;
132
133 return false;
134}
Hank Janssen3e7ee492009-07-13 16:02:34 -0700135
K. Y. Srinivasanb2a5a582011-05-10 07:55:30 -0700136/*
137 * hv_get_next_write_location()
138 *
139 * Get the next write location for the specified ring buffer
140 *
141 */
Greg Kroah-Hartman4d643112009-07-14 15:09:36 -0700142static inline u32
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700143hv_get_next_write_location(struct hv_ring_buffer_info *ring_info)
Hank Janssen3e7ee492009-07-13 16:02:34 -0700144{
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800145 u32 next = ring_info->ring_buffer->write_index;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700146
Hank Janssen3e7ee492009-07-13 16:02:34 -0700147 return next;
148}
149
K. Y. Srinivasanb2a5a582011-05-10 07:55:30 -0700150/*
151 * hv_set_next_write_location()
152 *
153 * Set the next write location for the specified ring buffer
154 *
155 */
Hank Janssen3e7ee492009-07-13 16:02:34 -0700156static inline void
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700157hv_set_next_write_location(struct hv_ring_buffer_info *ring_info,
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800158 u32 next_write_location)
Hank Janssen3e7ee492009-07-13 16:02:34 -0700159{
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800160 ring_info->ring_buffer->write_index = next_write_location;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700161}
162
K. Y. Srinivasanb2a5a582011-05-10 07:55:30 -0700163/*
164 * hv_get_next_read_location()
165 *
166 * Get the next read location for the specified ring buffer
167 */
Greg Kroah-Hartman4d643112009-07-14 15:09:36 -0700168static inline u32
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700169hv_get_next_read_location(struct hv_ring_buffer_info *ring_info)
Hank Janssen3e7ee492009-07-13 16:02:34 -0700170{
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800171 u32 next = ring_info->ring_buffer->read_index;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700172
Hank Janssen3e7ee492009-07-13 16:02:34 -0700173 return next;
174}
175
K. Y. Srinivasanb2a5a582011-05-10 07:55:30 -0700176/*
177 * hv_get_next_readlocation_withoffset()
178 *
179 * Get the next read location + offset for the specified ring buffer.
180 * This allows the caller to skip
181 */
Greg Kroah-Hartman4d643112009-07-14 15:09:36 -0700182static inline u32
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700183hv_get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info,
Haiyang Zhang1ac58642010-11-08 14:04:47 -0800184 u32 offset)
Hank Janssen3e7ee492009-07-13 16:02:34 -0700185{
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800186 u32 next = ring_info->ring_buffer->read_index;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700187
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800188 next += offset;
189 next %= ring_info->ring_datasize;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700190
191 return next;
192}
193
K. Y. Srinivasanb2a5a582011-05-10 07:55:30 -0700194/*
195 *
196 * hv_set_next_read_location()
197 *
198 * Set the next read location for the specified ring buffer
199 *
200 */
Hank Janssen3e7ee492009-07-13 16:02:34 -0700201static inline void
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700202hv_set_next_read_location(struct hv_ring_buffer_info *ring_info,
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800203 u32 next_read_location)
Hank Janssen3e7ee492009-07-13 16:02:34 -0700204{
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800205 ring_info->ring_buffer->read_index = next_read_location;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700206}
207
208
K. Y. Srinivasanb2a5a582011-05-10 07:55:30 -0700209/*
210 *
211 * hv_get_ring_buffer()
212 *
213 * Get the start of the ring buffer
214 */
Greg Kroah-Hartman8282c402009-07-14 15:06:28 -0700215static inline void *
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700216hv_get_ring_buffer(struct hv_ring_buffer_info *ring_info)
Hank Janssen3e7ee492009-07-13 16:02:34 -0700217{
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800218 return (void *)ring_info->ring_buffer->buffer;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700219}
220
221
K. Y. Srinivasanb2a5a582011-05-10 07:55:30 -0700222/*
223 *
224 * hv_get_ring_buffersize()
225 *
226 * Get the size of the ring buffer
227 */
Greg Kroah-Hartman4d643112009-07-14 15:09:36 -0700228static inline u32
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700229hv_get_ring_buffersize(struct hv_ring_buffer_info *ring_info)
Hank Janssen3e7ee492009-07-13 16:02:34 -0700230{
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800231 return ring_info->ring_datasize;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700232}
233
K. Y. Srinivasanb2a5a582011-05-10 07:55:30 -0700234/*
235 *
236 * hv_get_ring_bufferindices()
237 *
238 * Get the read and write indices as u64 of the specified ring buffer
239 *
240 */
Greg Kroah-Hartman59471432009-07-14 15:10:26 -0700241static inline u64
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700242hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info)
Hank Janssen3e7ee492009-07-13 16:02:34 -0700243{
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800244 return (u64)ring_info->ring_buffer->write_index << 32;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700245}
246
K. Y. Srinivasan8f1136a2011-05-10 07:55:31 -0700247/*
248 *
249 * hv_copyfrom_ringbuffer()
250 *
251 * Helper routine to copy to source from ring buffer.
252 * Assume there is enough room. Handles wrap-around in src case only!!
253 *
254 */
255static u32 hv_copyfrom_ringbuffer(
256 struct hv_ring_buffer_info *ring_info,
257 void *dest,
258 u32 destlen,
259 u32 start_read_offset)
260{
261 void *ring_buffer = hv_get_ring_buffer(ring_info);
262 u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);
263
264 u32 frag_len;
265
266 /* wrap-around detected at the src */
267 if (destlen > ring_buffer_size - start_read_offset) {
268 frag_len = ring_buffer_size - start_read_offset;
269
270 memcpy(dest, ring_buffer + start_read_offset, frag_len);
271 memcpy(dest + frag_len, ring_buffer, destlen - frag_len);
272 } else
273
274 memcpy(dest, ring_buffer + start_read_offset, destlen);
275
276
277 start_read_offset += destlen;
278 start_read_offset %= ring_buffer_size;
279
280 return start_read_offset;
281}
282
283
K. Y. Srinivasan75815782011-05-10 07:55:32 -0700284/*
285 *
286 * hv_copyto_ringbuffer()
287 *
288 * Helper routine to copy from source to ring buffer.
289 * Assume there is enough room. Handles wrap-around in dest case only!!
290 *
291 */
292static u32 hv_copyto_ringbuffer(
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800293 struct hv_ring_buffer_info *ring_info,
294 u32 start_write_offset,
295 void *src,
K. Y. Srinivasan75815782011-05-10 07:55:32 -0700296 u32 srclen)
297{
298 void *ring_buffer = hv_get_ring_buffer(ring_info);
299 u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);
300 u32 frag_len;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700301
K. Y. Srinivasan75815782011-05-10 07:55:32 -0700302 /* wrap-around detected! */
303 if (srclen > ring_buffer_size - start_write_offset) {
304 frag_len = ring_buffer_size - start_write_offset;
305 memcpy(ring_buffer + start_write_offset, src, frag_len);
306 memcpy(ring_buffer, src + frag_len, srclen - frag_len);
307 } else
308 memcpy(ring_buffer + start_write_offset, src, srclen);
309
310 start_write_offset += srclen;
311 start_write_offset %= ring_buffer_size;
312
313 return start_write_offset;
314}
Hank Janssen3e7ee492009-07-13 16:02:34 -0700315
K. Y. Srinivasanb2a5a582011-05-10 07:55:30 -0700316/*
317 *
318 * hv_ringbuffer_get_debuginfo()
319 *
320 * Get various debug metrics for the specified ring buffer
321 *
322 */
K. Y. Srinivasana75b61d2011-05-10 07:55:28 -0700323void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
Greg Kroah-Hartman80682b72010-07-27 11:37:32 -0700324 struct hv_ring_buffer_debug_info *debug_info)
Hank Janssen3e7ee492009-07-13 16:02:34 -0700325{
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800326 u32 bytes_avail_towrite;
327 u32 bytes_avail_toread;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700328
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800329 if (ring_info->ring_buffer) {
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700330 hv_get_ringbuffer_availbytes(ring_info,
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800331 &bytes_avail_toread,
332 &bytes_avail_towrite);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700333
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800334 debug_info->bytes_avail_toread = bytes_avail_toread;
335 debug_info->bytes_avail_towrite = bytes_avail_towrite;
Haiyang Zhang82f8bd42010-11-08 14:04:45 -0800336 debug_info->current_read_index =
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800337 ring_info->ring_buffer->read_index;
Haiyang Zhang82f8bd42010-11-08 14:04:45 -0800338 debug_info->current_write_index =
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800339 ring_info->ring_buffer->write_index;
Haiyang Zhang82f8bd42010-11-08 14:04:45 -0800340 debug_info->current_interrupt_mask =
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800341 ring_info->ring_buffer->interrupt_mask;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700342 }
343}
344
K. Y. Srinivasanb2a5a582011-05-10 07:55:30 -0700345/*
346 *
347 * hv_ringbuffer_init()
348 *
349 *Initialize the ring buffer
350 *
351 */
K. Y. Srinivasan72a95cb2011-05-10 07:55:21 -0700352int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800353 void *buffer, u32 buflen)
Hank Janssen3e7ee492009-07-13 16:02:34 -0700354{
Greg Kroah-Hartman4a1b3ac2010-07-27 11:47:08 -0700355 if (sizeof(struct hv_ring_buffer) != PAGE_SIZE)
Bill Pemberton3324fb42010-05-05 15:27:49 -0400356 return -EINVAL;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700357
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800358 memset(ring_info, 0, sizeof(struct hv_ring_buffer_info));
Hank Janssen3e7ee492009-07-13 16:02:34 -0700359
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800360 ring_info->ring_buffer = (struct hv_ring_buffer *)buffer;
361 ring_info->ring_buffer->read_index =
362 ring_info->ring_buffer->write_index = 0;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700363
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800364 ring_info->ring_size = buflen;
365 ring_info->ring_datasize = buflen - sizeof(struct hv_ring_buffer);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700366
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800367 spin_lock_init(&ring_info->ring_lock);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700368
369 return 0;
370}
371
K. Y. Srinivasanb2a5a582011-05-10 07:55:30 -0700372/*
373 *
374 * hv_ringbuffer_cleanup()
375 *
376 * Cleanup the ring buffer
377 *
378 */
K. Y. Srinivasan2dba6882011-05-10 07:55:22 -0700379void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
Hank Janssen3e7ee492009-07-13 16:02:34 -0700380{
Hank Janssen3e7ee492009-07-13 16:02:34 -0700381}
382
K. Y. Srinivasanb2a5a582011-05-10 07:55:30 -0700383/*
384 *
385 * hv_ringbuffer_write()
386 *
387 * Write to the ring buffer
388 *
389 */
K. Y. Srinivasan633c4dc2011-05-10 07:55:23 -0700390int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
K. Y. Srinivasan011a7c32014-02-01 19:02:20 -0800391 struct kvec *kv_list, u32 kv_count, bool *signal)
Hank Janssen3e7ee492009-07-13 16:02:34 -0700392{
C. Bartlett4408f532010-02-03 15:34:27 +0000393 int i = 0;
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800394 u32 bytes_avail_towrite;
395 u32 bytes_avail_toread;
396 u32 totalbytes_towrite = 0;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700397
K. Y. Srinivasan66a60542011-05-10 07:55:33 -0700398 u32 next_write_location;
K. Y. Srinivasan98fa8cf2012-12-01 06:46:36 -0800399 u32 old_write;
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800400 u64 prev_indices = 0;
Greg Kroah-Hartmana98f96e2009-07-15 14:55:14 -0700401 unsigned long flags;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700402
K. Y. Srinivasan011a7c32014-02-01 19:02:20 -0800403 for (i = 0; i < kv_count; i++)
404 totalbytes_towrite += kv_list[i].iov_len;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700405
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800406 totalbytes_towrite += sizeof(u64);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700407
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800408 spin_lock_irqsave(&outring_info->ring_lock, flags);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700409
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700410 hv_get_ringbuffer_availbytes(outring_info,
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800411 &bytes_avail_toread,
412 &bytes_avail_towrite);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700413
Hank Janssen3e7ee492009-07-13 16:02:34 -0700414
C. Bartlett4408f532010-02-03 15:34:27 +0000415 /* If there is only room for the packet, assume it is full. */
416 /* Otherwise, the next time around, we think the ring buffer */
Bill Pemberton454f18a2009-07-27 16:47:24 -0400417 /* is empty since the read index == write index */
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800418 if (bytes_avail_towrite <= totalbytes_towrite) {
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800419 spin_unlock_irqrestore(&outring_info->ring_lock, flags);
K. Y. Srinivasand2598f02011-08-25 09:48:58 -0700420 return -EAGAIN;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700421 }
422
Bill Pemberton454f18a2009-07-27 16:47:24 -0400423 /* Write to the ring buffer */
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700424 next_write_location = hv_get_next_write_location(outring_info);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700425
K. Y. Srinivasan98fa8cf2012-12-01 06:46:36 -0800426 old_write = next_write_location;
427
K. Y. Srinivasan011a7c32014-02-01 19:02:20 -0800428 for (i = 0; i < kv_count; i++) {
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700429 next_write_location = hv_copyto_ringbuffer(outring_info,
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800430 next_write_location,
K. Y. Srinivasan011a7c32014-02-01 19:02:20 -0800431 kv_list[i].iov_base,
432 kv_list[i].iov_len);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700433 }
434
Bill Pemberton454f18a2009-07-27 16:47:24 -0400435 /* Set previous packet start */
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700436 prev_indices = hv_get_ring_bufferindices(outring_info);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700437
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700438 next_write_location = hv_copyto_ringbuffer(outring_info,
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800439 next_write_location,
440 &prev_indices,
Nicolas Palixb219b3f2009-07-30 17:37:23 +0200441 sizeof(u64));
Hank Janssen3e7ee492009-07-13 16:02:34 -0700442
K. Y. Srinivasan98fa8cf2012-12-01 06:46:36 -0800443 /* Issue a full memory barrier before updating the write index */
Jason Wang35848f62013-06-18 13:04:23 +0800444 mb();
Hank Janssen3e7ee492009-07-13 16:02:34 -0700445
Bill Pemberton454f18a2009-07-27 16:47:24 -0400446 /* Now, update the write location */
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700447 hv_set_next_write_location(outring_info, next_write_location);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700448
Hank Janssen3e7ee492009-07-13 16:02:34 -0700449
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800450 spin_unlock_irqrestore(&outring_info->ring_lock, flags);
K. Y. Srinivasan98fa8cf2012-12-01 06:46:36 -0800451
452 *signal = hv_need_to_signal(old_write, outring_info);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700453 return 0;
454}
455
456
K. Y. Srinivasanb2a5a582011-05-10 07:55:30 -0700457/*
458 *
459 * hv_ringbuffer_peek()
460 *
461 * Read without advancing the read index
462 *
463 */
K. Y. Srinivasana89186c2011-05-10 07:55:24 -0700464int hv_ringbuffer_peek(struct hv_ring_buffer_info *Inring_info,
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800465 void *Buffer, u32 buflen)
Hank Janssen3e7ee492009-07-13 16:02:34 -0700466{
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800467 u32 bytes_avail_towrite;
468 u32 bytes_avail_toread;
469 u32 next_read_location = 0;
Greg Kroah-Hartmana98f96e2009-07-15 14:55:14 -0700470 unsigned long flags;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700471
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800472 spin_lock_irqsave(&Inring_info->ring_lock, flags);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700473
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700474 hv_get_ringbuffer_availbytes(Inring_info,
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800475 &bytes_avail_toread,
476 &bytes_avail_towrite);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700477
Bill Pemberton454f18a2009-07-27 16:47:24 -0400478 /* Make sure there is something to read */
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800479 if (bytes_avail_toread < buflen) {
Hank Janssen3e7ee492009-07-13 16:02:34 -0700480
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800481 spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700482
K. Y. Srinivasand2598f02011-08-25 09:48:58 -0700483 return -EAGAIN;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700484 }
485
Bill Pemberton454f18a2009-07-27 16:47:24 -0400486 /* Convert to byte offset */
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700487 next_read_location = hv_get_next_read_location(Inring_info);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700488
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700489 next_read_location = hv_copyfrom_ringbuffer(Inring_info,
C. Bartlett4408f532010-02-03 15:34:27 +0000490 Buffer,
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800491 buflen,
492 next_read_location);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700493
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800494 spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700495
496 return 0;
497}
498
499
K. Y. Srinivasanb2a5a582011-05-10 07:55:30 -0700500/*
501 *
502 * hv_ringbuffer_read()
503 *
504 * Read and advance the read index
505 *
506 */
K. Y. Srinivasan38397c82011-05-10 07:55:25 -0700507int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, void *buffer,
K. Y. Srinivasanc2b8e522012-12-01 06:46:57 -0800508 u32 buflen, u32 offset, bool *signal)
Hank Janssen3e7ee492009-07-13 16:02:34 -0700509{
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800510 u32 bytes_avail_towrite;
511 u32 bytes_avail_toread;
512 u32 next_read_location = 0;
513 u64 prev_indices = 0;
Greg Kroah-Hartmana98f96e2009-07-15 14:55:14 -0700514 unsigned long flags;
K. Y. Srinivasanc2b8e522012-12-01 06:46:57 -0800515 u32 old_read;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700516
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800517 if (buflen <= 0)
Bill Pembertona16e1482010-05-05 15:27:50 -0400518 return -EINVAL;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700519
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800520 spin_lock_irqsave(&inring_info->ring_lock, flags);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700521
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700522 hv_get_ringbuffer_availbytes(inring_info,
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800523 &bytes_avail_toread,
524 &bytes_avail_towrite);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700525
K. Y. Srinivasanc2b8e522012-12-01 06:46:57 -0800526 old_read = bytes_avail_toread;
527
Bill Pemberton454f18a2009-07-27 16:47:24 -0400528 /* Make sure there is something to read */
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800529 if (bytes_avail_toread < buflen) {
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800530 spin_unlock_irqrestore(&inring_info->ring_lock, flags);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700531
K. Y. Srinivasand2598f02011-08-25 09:48:58 -0700532 return -EAGAIN;
Hank Janssen3e7ee492009-07-13 16:02:34 -0700533 }
534
Haiyang Zhang1ac58642010-11-08 14:04:47 -0800535 next_read_location =
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700536 hv_get_next_readlocation_withoffset(inring_info, offset);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700537
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700538 next_read_location = hv_copyfrom_ringbuffer(inring_info,
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800539 buffer,
540 buflen,
541 next_read_location);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700542
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700543 next_read_location = hv_copyfrom_ringbuffer(inring_info,
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800544 &prev_indices,
C. Bartlett4408f532010-02-03 15:34:27 +0000545 sizeof(u64),
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800546 next_read_location);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700547
Bill Pemberton454f18a2009-07-27 16:47:24 -0400548 /* Make sure all reads are done before we update the read index since */
C. Bartlett4408f532010-02-03 15:34:27 +0000549 /* the writer may start writing to the read area once the read index */
550 /*is updated */
Jason Wang35848f62013-06-18 13:04:23 +0800551 mb();
Hank Janssen3e7ee492009-07-13 16:02:34 -0700552
Bill Pemberton454f18a2009-07-27 16:47:24 -0400553 /* Update the read index */
K. Y. Srinivasan2b8a9122011-05-10 07:55:29 -0700554 hv_set_next_read_location(inring_info, next_read_location);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700555
Haiyang Zhangfc8c72e2010-11-08 14:04:46 -0800556 spin_unlock_irqrestore(&inring_info->ring_lock, flags);
Hank Janssen3e7ee492009-07-13 16:02:34 -0700557
K. Y. Srinivasanc2b8e522012-12-01 06:46:57 -0800558 *signal = hv_need_to_signal_on_read(old_read, inring_info);
559
Hank Janssen3e7ee492009-07-13 16:02:34 -0700560 return 0;
561}