| @@ -1,316 +1,316 @@ | | | @@ -1,316 +1,316 @@ |
1 | /* $NetBSD: ring.h,v 1.11 2008/08/22 15:28:11 cegger Exp $ */ | | 1 | /* $NetBSD: ring.h,v 1.12 2011/07/27 23:10:40 matt Exp $ */ |
2 | /****************************************************************************** | | 2 | /****************************************************************************** |
3 | * ring.h | | 3 | * ring.h |
4 | * | | 4 | * |
5 | * Shared producer-consumer ring macros. | | 5 | * Shared producer-consumer ring macros. |
6 | * | | 6 | * |
7 | * Permission is hereby granted, free of charge, to any person obtaining a copy | | 7 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
8 | * of this software and associated documentation files (the "Software"), to | | 8 | * of this software and associated documentation files (the "Software"), to |
9 | * deal in the Software without restriction, including without limitation the | | 9 | * deal in the Software without restriction, including without limitation the |
10 | * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or | | 10 | * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or |
11 | * sell copies of the Software, and to permit persons to whom the Software is | | 11 | * sell copies of the Software, and to permit persons to whom the Software is |
12 | * furnished to do so, subject to the following conditions: | | 12 | * furnished to do so, subject to the following conditions: |
13 | * | | 13 | * |
14 | * The above copyright notice and this permission notice shall be included in | | 14 | * The above copyright notice and this permission notice shall be included in |
15 | * all copies or substantial portions of the Software. | | 15 | * all copies or substantial portions of the Software. |
16 | * | | 16 | * |
17 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | | 17 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
18 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | | 18 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
19 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | | 19 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
20 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | | 20 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
21 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | | 21 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
22 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER | | 22 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
23 | * DEALINGS IN THE SOFTWARE. | | 23 | * DEALINGS IN THE SOFTWARE. |
24 | * | | 24 | * |
25 | * Tim Deegan and Andrew Warfield November 2004. | | 25 | * Tim Deegan and Andrew Warfield November 2004. |
26 | */ | | 26 | */ |
27 | | | 27 | |
28 | #ifndef __XEN_PUBLIC_IO_RING_H__ | | 28 | #ifndef __XEN_PUBLIC_IO_RING_H__ |
29 | #define __XEN_PUBLIC_IO_RING_H__ | | 29 | #define __XEN_PUBLIC_IO_RING_H__ |
30 | | | 30 | |
31 | #include "../xen-compat.h" | | 31 | #include "../xen-compat.h" |
32 | | | 32 | |
33 | #if __XEN_INTERFACE_VERSION__ < 0x00030208 | | 33 | #if __XEN_INTERFACE_VERSION__ < 0x00030208 |
34 | #if defined(__Linux__) | | 34 | #if defined(__Linux__) |
35 | #define xen_mb() mb() | | 35 | #define xen_mb() mb() |
36 | #define xen_rmb() rmb() | | 36 | #define xen_rmb() rmb() |
37 | #define xen_wmb() wmb() | | 37 | #define xen_wmb() wmb() |
38 | #endif | | 38 | #endif |
39 | #endif | | 39 | #endif |
40 | | | 40 | |
41 | #if defined(__NetBSD__) | | 41 | #if defined(__NetBSD__) |
42 | #define xen_mb() x86_mfence() | | 42 | #define xen_mb() x86_mfence() |
43 | #define xen_rmb() x86_lfence() | | 43 | #define xen_rmb() x86_lfence() |
44 | #define xen_wmb() x86_sfence() | | 44 | #define xen_wmb() x86_sfence() |
45 | #endif | | 45 | #endif |
46 | | | 46 | |
47 | typedef unsigned int RING_IDX; | | 47 | typedef unsigned int RING_IDX; |
48 | | | 48 | |
49 | /* Round a 32-bit unsigned constant down to the nearest power of two. */ | | 49 | /* Round a 32-bit unsigned constant down to the nearest power of two. */ |
50 | #define __RD2(_x) (((_x) & 0x00000002) ? 0x2 : ((_x) & 0x1)) | | 50 | #define __RD2(_x) (((_x) & 0x00000002) ? 0x2 : ((_x) & 0x1)) |
51 | #define __RD4(_x) (((_x) & 0x0000000c) ? __RD2((_x)>>2)<<2 : __RD2(_x)) | | 51 | #define __RD4(_x) (((_x) & 0x0000000c) ? __RD2((_x)>>2)<<2 : __RD2(_x)) |
52 | #define __RD8(_x) (((_x) & 0x000000f0) ? __RD4((_x)>>4)<<4 : __RD4(_x)) | | 52 | #define __RD8(_x) (((_x) & 0x000000f0) ? __RD4((_x)>>4)<<4 : __RD4(_x)) |
53 | #define __RD16(_x) (((_x) & 0x0000ff00) ? __RD8((_x)>>8)<<8 : __RD8(_x)) | | 53 | #define __RD16(_x) (((_x) & 0x0000ff00) ? __RD8((_x)>>8)<<8 : __RD8(_x)) |
54 | #define __RD32(_x) (((_x) & 0xffff0000) ? __RD16((_x)>>16)<<16 : __RD16(_x)) | | 54 | #define __RD32(_x) (((_x) & 0xffff0000) ? __RD16((_x)>>16)<<16 : __RD16(_x)) |
55 | | | 55 | |
56 | /* | | 56 | /* |
57 | * Calculate size of a shared ring, given the total available space for the | | 57 | * Calculate size of a shared ring, given the total available space for the |
58 | * ring and indexes (_sz), and the name tag of the request/response structure. | | 58 | * ring and indexes (_sz), and the name tag of the request/response structure. |
59 | * A ring contains as many entries as will fit, rounded down to the nearest | | 59 | * A ring contains as many entries as will fit, rounded down to the nearest |
60 | * power of two (so we can mask with (size-1) to loop around). | | 60 | * power of two (so we can mask with (size-1) to loop around). |
61 | */ | | 61 | */ |
62 | #define __RING_SIZE(_s, _sz) \ | | 62 | #define __RING_SIZE(_s, _sz) \ |
63 | (__RD32(((_sz) - (long)(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0]))) | | 63 | (__RD32(((_sz) - offsetof(__typeof__(*(_s)), ring)) / sizeof((_s)->ring[0]))) |
64 | | | 64 | |
65 | /* | | 65 | /* |
66 | * Macros to make the correct C datatypes for a new kind of ring. | | 66 | * Macros to make the correct C datatypes for a new kind of ring. |
67 | * | | 67 | * |
68 | * To make a new ring datatype, you need to have two message structures, | | 68 | * To make a new ring datatype, you need to have two message structures, |
69 | * let's say request_t, and response_t already defined. | | 69 | * let's say request_t, and response_t already defined. |
70 | * | | 70 | * |
71 | * In a header where you want the ring datatype declared, you then do: | | 71 | * In a header where you want the ring datatype declared, you then do: |
72 | * | | 72 | * |
73 | * DEFINE_RING_TYPES(mytag, request_t, response_t); | | 73 | * DEFINE_RING_TYPES(mytag, request_t, response_t); |
74 | * | | 74 | * |
75 | * These expand out to give you a set of types, as you can see below. | | 75 | * These expand out to give you a set of types, as you can see below. |
76 | * The most important of these are: | | 76 | * The most important of these are: |
77 | * | | 77 | * |
78 | * mytag_sring_t - The shared ring. | | 78 | * mytag_sring_t - The shared ring. |
79 | * mytag_front_ring_t - The 'front' half of the ring. | | 79 | * mytag_front_ring_t - The 'front' half of the ring. |
80 | * mytag_back_ring_t - The 'back' half of the ring. | | 80 | * mytag_back_ring_t - The 'back' half of the ring. |
81 | * | | 81 | * |
82 | * To initialize a ring in your code you need to know the location and size | | 82 | * To initialize a ring in your code you need to know the location and size |
83 | * of the shared memory area (PAGE_SIZE, for instance). To initialise | | 83 | * of the shared memory area (PAGE_SIZE, for instance). To initialise |
84 | * the front half: | | 84 | * the front half: |
85 | * | | 85 | * |
86 | * mytag_front_ring_t front_ring; | | 86 | * mytag_front_ring_t front_ring; |
87 | * SHARED_RING_INIT((mytag_sring_t *)shared_page); | | 87 | * SHARED_RING_INIT((mytag_sring_t *)shared_page); |
88 | * FRONT_RING_INIT(&front_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); | | 88 | * FRONT_RING_INIT(&front_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); |
89 | * | | 89 | * |
90 | * Initializing the back follows similarly (note that only the front | | 90 | * Initializing the back follows similarly (note that only the front |
91 | * initializes the shared ring): | | 91 | * initializes the shared ring): |
92 | * | | 92 | * |
93 | * mytag_back_ring_t back_ring; | | 93 | * mytag_back_ring_t back_ring; |
94 | * BACK_RING_INIT(&back_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); | | 94 | * BACK_RING_INIT(&back_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); |
95 | */ | | 95 | */ |
96 | | | 96 | |
97 | #define DEFINE_RING_TYPES(__name, __req_t, __rsp_t) \ | | 97 | #define DEFINE_RING_TYPES(__name, __req_t, __rsp_t) \ |
98 | \ | | 98 | \ |
99 | /* Shared ring entry */ \ | | 99 | /* Shared ring entry */ \ |
100 | union __name##_sring_entry { \ | | 100 | union __name##_sring_entry { \ |
101 | __req_t req; \ | | 101 | __req_t req; \ |
102 | __rsp_t rsp; \ | | 102 | __rsp_t rsp; \ |
103 | }; \ | | 103 | }; \ |
104 | \ | | 104 | \ |
105 | /* Shared ring page */ \ | | 105 | /* Shared ring page */ \ |
106 | struct __name##_sring { \ | | 106 | struct __name##_sring { \ |
107 | RING_IDX req_prod, req_event; \ | | 107 | RING_IDX req_prod, req_event; \ |
108 | RING_IDX rsp_prod, rsp_event; \ | | 108 | RING_IDX rsp_prod, rsp_event; \ |
109 | uint8_t pad[48]; \ | | 109 | uint8_t pad[48]; \ |
110 | union __name##_sring_entry ring[1]; /* variable-length */ \ | | 110 | union __name##_sring_entry ring[1]; /* variable-length */ \ |
111 | }; \ | | 111 | }; \ |
112 | \ | | 112 | \ |
113 | /* "Front" end's private variables */ \ | | 113 | /* "Front" end's private variables */ \ |
114 | struct __name##_front_ring { \ | | 114 | struct __name##_front_ring { \ |
115 | RING_IDX req_prod_pvt; \ | | 115 | RING_IDX req_prod_pvt; \ |
116 | RING_IDX rsp_cons; \ | | 116 | RING_IDX rsp_cons; \ |
117 | unsigned int nr_ents; \ | | 117 | unsigned int nr_ents; \ |
118 | struct __name##_sring *sring; \ | | 118 | struct __name##_sring *sring; \ |
119 | }; \ | | 119 | }; \ |
120 | \ | | 120 | \ |
121 | /* "Back" end's private variables */ \ | | 121 | /* "Back" end's private variables */ \ |
122 | struct __name##_back_ring { \ | | 122 | struct __name##_back_ring { \ |
123 | RING_IDX rsp_prod_pvt; \ | | 123 | RING_IDX rsp_prod_pvt; \ |
124 | RING_IDX req_cons; \ | | 124 | RING_IDX req_cons; \ |
125 | unsigned int nr_ents; \ | | 125 | unsigned int nr_ents; \ |
126 | struct __name##_sring *sring; \ | | 126 | struct __name##_sring *sring; \ |
127 | }; \ | | 127 | }; \ |
128 | \ | | 128 | \ |
129 | /* Syntactic sugar */ \ | | 129 | /* Syntactic sugar */ \ |
130 | typedef struct __name##_sring __name##_sring_t; \ | | 130 | typedef struct __name##_sring __name##_sring_t; \ |
131 | typedef struct __name##_front_ring __name##_front_ring_t; \ | | 131 | typedef struct __name##_front_ring __name##_front_ring_t; \ |
132 | typedef struct __name##_back_ring __name##_back_ring_t | | 132 | typedef struct __name##_back_ring __name##_back_ring_t |
133 | | | 133 | |
134 | /* | | 134 | /* |
135 | * Macros for manipulating rings. | | 135 | * Macros for manipulating rings. |
136 | * | | 136 | * |
137 | * FRONT_RING_whatever works on the "front end" of a ring: here | | 137 | * FRONT_RING_whatever works on the "front end" of a ring: here |
138 | * requests are pushed on to the ring and responses taken off it. | | 138 | * requests are pushed on to the ring and responses taken off it. |
139 | * | | 139 | * |
140 | * BACK_RING_whatever works on the "back end" of a ring: here | | 140 | * BACK_RING_whatever works on the "back end" of a ring: here |
141 | * requests are taken off the ring and responses put on. | | 141 | * requests are taken off the ring and responses put on. |
142 | * | | 142 | * |
143 | * N.B. these macros do NO INTERLOCKS OR FLOW CONTROL. | | 143 | * N.B. these macros do NO INTERLOCKS OR FLOW CONTROL. |
144 | * This is OK in 1-for-1 request-response situations where the | | 144 | * This is OK in 1-for-1 request-response situations where the |
145 | * requestor (front end) never has more than RING_SIZE()-1 | | 145 | * requestor (front end) never has more than RING_SIZE()-1 |
146 | * outstanding requests. | | 146 | * outstanding requests. |
147 | */ | | 147 | */ |
148 | | | 148 | |
149 | /* Initialising empty rings */ | | 149 | /* Initialising empty rings */ |
150 | #define SHARED_RING_INIT(_s) do { \ | | 150 | #define SHARED_RING_INIT(_s) do { \ |
151 | (_s)->req_prod = (_s)->rsp_prod = 0; \ | | 151 | (_s)->req_prod = (_s)->rsp_prod = 0; \ |
152 | (_s)->req_event = (_s)->rsp_event = 1; \ | | 152 | (_s)->req_event = (_s)->rsp_event = 1; \ |
153 | (void)memset((_s)->pad, 0, sizeof((_s)->pad)); \ | | 153 | (void)memset((_s)->pad, 0, sizeof((_s)->pad)); \ |
154 | } while(0) | | 154 | } while(0) |
155 | | | 155 | |
156 | #define FRONT_RING_INIT(_r, _s, __size) do { \ | | 156 | #define FRONT_RING_INIT(_r, _s, __size) do { \ |
157 | (_r)->req_prod_pvt = 0; \ | | 157 | (_r)->req_prod_pvt = 0; \ |
158 | (_r)->rsp_cons = 0; \ | | 158 | (_r)->rsp_cons = 0; \ |
159 | (_r)->nr_ents = __RING_SIZE(_s, __size); \ | | 159 | (_r)->nr_ents = __RING_SIZE(_s, __size); \ |
160 | (_r)->sring = (_s); \ | | 160 | (_r)->sring = (_s); \ |
161 | } while (0) | | 161 | } while (0) |
162 | | | 162 | |
163 | #define BACK_RING_INIT(_r, _s, __size) do { \ | | 163 | #define BACK_RING_INIT(_r, _s, __size) do { \ |
164 | (_r)->rsp_prod_pvt = 0; \ | | 164 | (_r)->rsp_prod_pvt = 0; \ |
165 | (_r)->req_cons = 0; \ | | 165 | (_r)->req_cons = 0; \ |
166 | (_r)->nr_ents = __RING_SIZE(_s, __size); \ | | 166 | (_r)->nr_ents = __RING_SIZE(_s, __size); \ |
167 | (_r)->sring = (_s); \ | | 167 | (_r)->sring = (_s); \ |
168 | } while (0) | | 168 | } while (0) |
169 | | | 169 | |
170 | /* Initialize to existing shared indexes -- for recovery */ | | 170 | /* Initialize to existing shared indexes -- for recovery */ |
171 | #define FRONT_RING_ATTACH(_r, _s, __size) do { \ | | 171 | #define FRONT_RING_ATTACH(_r, _s, __size) do { \ |
172 | (_r)->sring = (_s); \ | | 172 | (_r)->sring = (_s); \ |
173 | (_r)->req_prod_pvt = (_s)->req_prod; \ | | 173 | (_r)->req_prod_pvt = (_s)->req_prod; \ |
174 | (_r)->rsp_cons = (_s)->rsp_prod; \ | | 174 | (_r)->rsp_cons = (_s)->rsp_prod; \ |
175 | (_r)->nr_ents = __RING_SIZE(_s, __size); \ | | 175 | (_r)->nr_ents = __RING_SIZE(_s, __size); \ |
176 | } while (0) | | 176 | } while (0) |
177 | | | 177 | |
178 | #define BACK_RING_ATTACH(_r, _s, __size) do { \ | | 178 | #define BACK_RING_ATTACH(_r, _s, __size) do { \ |
179 | (_r)->sring = (_s); \ | | 179 | (_r)->sring = (_s); \ |
180 | (_r)->rsp_prod_pvt = (_s)->rsp_prod; \ | | 180 | (_r)->rsp_prod_pvt = (_s)->rsp_prod; \ |
181 | (_r)->req_cons = (_s)->req_prod; \ | | 181 | (_r)->req_cons = (_s)->req_prod; \ |
182 | (_r)->nr_ents = __RING_SIZE(_s, __size); \ | | 182 | (_r)->nr_ents = __RING_SIZE(_s, __size); \ |
183 | } while (0) | | 183 | } while (0) |
184 | | | 184 | |
185 | /* How big is this ring? */ | | 185 | /* How big is this ring? */ |
186 | #define RING_SIZE(_r) \ | | 186 | #define RING_SIZE(_r) \ |
187 | ((_r)->nr_ents) | | 187 | ((_r)->nr_ents) |
188 | | | 188 | |
189 | /* Number of free requests (for use on front side only). */ | | 189 | /* Number of free requests (for use on front side only). */ |
190 | #define RING_FREE_REQUESTS(_r) \ | | 190 | #define RING_FREE_REQUESTS(_r) \ |
191 | (RING_SIZE(_r) - ((_r)->req_prod_pvt - (_r)->rsp_cons)) | | 191 | (RING_SIZE(_r) - ((_r)->req_prod_pvt - (_r)->rsp_cons)) |
192 | | | 192 | |
193 | /* Test if there is an empty slot available on the front ring. | | 193 | /* Test if there is an empty slot available on the front ring. |
194 | * (This is only meaningful from the front. ) | | 194 | * (This is only meaningful from the front. ) |
195 | */ | | 195 | */ |
196 | #define RING_FULL(_r) \ | | 196 | #define RING_FULL(_r) \ |
197 | (RING_FREE_REQUESTS(_r) == 0) | | 197 | (RING_FREE_REQUESTS(_r) == 0) |
198 | | | 198 | |
199 | /* Test if there are outstanding messages to be processed on a ring. */ | | 199 | /* Test if there are outstanding messages to be processed on a ring. */ |
200 | #define RING_HAS_UNCONSUMED_RESPONSES(_r) \ | | 200 | #define RING_HAS_UNCONSUMED_RESPONSES(_r) \ |
201 | ((_r)->sring->rsp_prod - (_r)->rsp_cons) | | 201 | ((_r)->sring->rsp_prod - (_r)->rsp_cons) |
202 | | | 202 | |
203 | #ifdef __GNUC__ | | 203 | #ifdef __GNUC__ |
204 | #define RING_HAS_UNCONSUMED_REQUESTS(_r) ({ \ | | 204 | #define RING_HAS_UNCONSUMED_REQUESTS(_r) ({ \ |
205 | unsigned int req = (_r)->sring->req_prod - (_r)->req_cons; \ | | 205 | unsigned int req = (_r)->sring->req_prod - (_r)->req_cons; \ |
206 | unsigned int rsp = RING_SIZE(_r) - \ | | 206 | unsigned int rsp = RING_SIZE(_r) - \ |
207 | ((_r)->req_cons - (_r)->rsp_prod_pvt); \ | | 207 | ((_r)->req_cons - (_r)->rsp_prod_pvt); \ |
208 | req < rsp ? req : rsp; \ | | 208 | req < rsp ? req : rsp; \ |
209 | }) | | 209 | }) |
210 | #else | | 210 | #else |
211 | /* Same as above, but without the nice GCC ({ ... }) syntax. */ | | 211 | /* Same as above, but without the nice GCC ({ ... }) syntax. */ |
212 | #define RING_HAS_UNCONSUMED_REQUESTS(_r) \ | | 212 | #define RING_HAS_UNCONSUMED_REQUESTS(_r) \ |
213 | ((((_r)->sring->req_prod - (_r)->req_cons) < \ | | 213 | ((((_r)->sring->req_prod - (_r)->req_cons) < \ |
214 | (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) ? \ | | 214 | (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) ? \ |
215 | ((_r)->sring->req_prod - (_r)->req_cons) : \ | | 215 | ((_r)->sring->req_prod - (_r)->req_cons) : \ |
216 | (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) | | 216 | (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) |
217 | #endif | | 217 | #endif |
218 | | | 218 | |
219 | /* Direct access to individual ring elements, by index. */ | | 219 | /* Direct access to individual ring elements, by index. */ |
220 | #define RING_GET_REQUEST(_r, _idx) \ | | 220 | #define RING_GET_REQUEST(_r, _idx) \ |
221 | (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req)) | | 221 | (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req)) |
222 | | | 222 | |
223 | #define RING_GET_RESPONSE(_r, _idx) \ | | 223 | #define RING_GET_RESPONSE(_r, _idx) \ |
224 | (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp)) | | 224 | (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp)) |
225 | | | 225 | |
226 | /* Loop termination condition: Would the specified index overflow the ring? */ | | 226 | /* Loop termination condition: Would the specified index overflow the ring? */ |
227 | #define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \ | | 227 | #define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \ |
228 | (((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r)) | | 228 | (((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r)) |
229 | | | 229 | |
230 | #define RING_PUSH_REQUESTS(_r) do { \ | | 230 | #define RING_PUSH_REQUESTS(_r) do { \ |
231 | xen_wmb(); /* back sees requests /before/ updated producer index */ \ | | 231 | xen_wmb(); /* back sees requests /before/ updated producer index */ \ |
232 | (_r)->sring->req_prod = (_r)->req_prod_pvt; \ | | 232 | (_r)->sring->req_prod = (_r)->req_prod_pvt; \ |
233 | } while (0) | | 233 | } while (0) |
234 | | | 234 | |
235 | #define RING_PUSH_RESPONSES(_r) do { \ | | 235 | #define RING_PUSH_RESPONSES(_r) do { \ |
236 | xen_wmb(); /* front sees resps /before/ updated producer index */ \ | | 236 | xen_wmb(); /* front sees resps /before/ updated producer index */ \ |
237 | (_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \ | | 237 | (_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \ |
238 | } while (0) | | 238 | } while (0) |
239 | | | 239 | |
240 | /* | | 240 | /* |
241 | * Notification hold-off (req_event and rsp_event): | | 241 | * Notification hold-off (req_event and rsp_event): |
242 | * | | 242 | * |
243 | * When queueing requests or responses on a shared ring, it may not always be | | 243 | * When queueing requests or responses on a shared ring, it may not always be |
244 | * necessary to notify the remote end. For example, if requests are in flight | | 244 | * necessary to notify the remote end. For example, if requests are in flight |
245 | * in a backend, the front may be able to queue further requests without | | 245 | * in a backend, the front may be able to queue further requests without |
246 | * notifying the back (if the back checks for new requests when it queues | | 246 | * notifying the back (if the back checks for new requests when it queues |
247 | * responses). | | 247 | * responses). |
248 | * | | 248 | * |
249 | * When enqueuing requests or responses: | | 249 | * When enqueuing requests or responses: |
250 | * | | 250 | * |
251 | * Use RING_PUSH_{REQUESTS,RESPONSES}_AND_CHECK_NOTIFY(). The second argument | | 251 | * Use RING_PUSH_{REQUESTS,RESPONSES}_AND_CHECK_NOTIFY(). The second argument |
252 | * is a boolean return value. True indicates that the receiver requires an | | 252 | * is a boolean return value. True indicates that the receiver requires an |
253 | * asynchronous notification. | | 253 | * asynchronous notification. |
254 | * | | 254 | * |
255 | * After dequeuing requests or responses (before sleeping the connection): | | 255 | * After dequeuing requests or responses (before sleeping the connection): |
256 | * | | 256 | * |
257 | * Use RING_FINAL_CHECK_FOR_REQUESTS() or RING_FINAL_CHECK_FOR_RESPONSES(). | | 257 | * Use RING_FINAL_CHECK_FOR_REQUESTS() or RING_FINAL_CHECK_FOR_RESPONSES(). |
258 | * The second argument is a boolean return value. True indicates that there | | 258 | * The second argument is a boolean return value. True indicates that there |
259 | * are pending messages on the ring (i.e., the connection should not be put | | 259 | * are pending messages on the ring (i.e., the connection should not be put |
260 | * to sleep). | | 260 | * to sleep). |
261 | * | | 261 | * |
262 | * These macros will set the req_event/rsp_event field to trigger a | | 262 | * These macros will set the req_event/rsp_event field to trigger a |
263 | * notification on the very next message that is enqueued. If you want to | | 263 | * notification on the very next message that is enqueued. If you want to |
264 | * create batches of work (i.e., only receive a notification after several | | 264 | * create batches of work (i.e., only receive a notification after several |
265 | * messages have been enqueued) then you will need to create a customised | | 265 | * messages have been enqueued) then you will need to create a customised |
266 | * version of the FINAL_CHECK macro in your own code, which sets the event | | 266 | * version of the FINAL_CHECK macro in your own code, which sets the event |
267 | * field appropriately. | | 267 | * field appropriately. |
268 | */ | | 268 | */ |
269 | | | 269 | |
270 | #define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \ | | 270 | #define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \ |
271 | RING_IDX __old = (_r)->sring->req_prod; \ | | 271 | RING_IDX __old = (_r)->sring->req_prod; \ |
272 | RING_IDX __new = (_r)->req_prod_pvt; \ | | 272 | RING_IDX __new = (_r)->req_prod_pvt; \ |
273 | xen_wmb(); /* back sees requests /before/ updated producer index */ \ | | 273 | xen_wmb(); /* back sees requests /before/ updated producer index */ \ |
274 | (_r)->sring->req_prod = __new; \ | | 274 | (_r)->sring->req_prod = __new; \ |
275 | xen_mb(); /* back sees new requests /before/ we check req_event */ \ | | 275 | xen_mb(); /* back sees new requests /before/ we check req_event */ \ |
276 | (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \ | | 276 | (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \ |
277 | (RING_IDX)(__new - __old)); \ | | 277 | (RING_IDX)(__new - __old)); \ |
278 | } while (0) | | 278 | } while (0) |
279 | | | 279 | |
280 | #define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \ | | 280 | #define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \ |
281 | RING_IDX __old = (_r)->sring->rsp_prod; \ | | 281 | RING_IDX __old = (_r)->sring->rsp_prod; \ |
282 | RING_IDX __new = (_r)->rsp_prod_pvt; \ | | 282 | RING_IDX __new = (_r)->rsp_prod_pvt; \ |
283 | xen_wmb(); /* front sees resps /before/ updated producer index */ \ | | 283 | xen_wmb(); /* front sees resps /before/ updated producer index */ \ |
284 | (_r)->sring->rsp_prod = __new; \ | | 284 | (_r)->sring->rsp_prod = __new; \ |
285 | xen_mb(); /* front sees new resps /before/ we check rsp_event */ \ | | 285 | xen_mb(); /* front sees new resps /before/ we check rsp_event */ \ |
286 | (_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \ | | 286 | (_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \ |
287 | (RING_IDX)(__new - __old)); \ | | 287 | (RING_IDX)(__new - __old)); \ |
288 | } while (0) | | 288 | } while (0) |
289 | | | 289 | |
290 | #define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do { \ | | 290 | #define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do { \ |
291 | (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ | | 291 | (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ |
292 | if (_work_to_do) break; \ | | 292 | if (_work_to_do) break; \ |
293 | (_r)->sring->req_event = (_r)->req_cons + 1; \ | | 293 | (_r)->sring->req_event = (_r)->req_cons + 1; \ |
294 | xen_mb(); \ | | 294 | xen_mb(); \ |
295 | (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ | | 295 | (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ |
296 | } while (0) | | 296 | } while (0) |
297 | | | 297 | |
298 | #define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do { \ | | 298 | #define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do { \ |
299 | (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ | | 299 | (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ |
300 | if (_work_to_do) break; \ | | 300 | if (_work_to_do) break; \ |
301 | (_r)->sring->rsp_event = (_r)->rsp_cons + 1; \ | | 301 | (_r)->sring->rsp_event = (_r)->rsp_cons + 1; \ |
302 | xen_mb(); \ | | 302 | xen_mb(); \ |
303 | (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ | | 303 | (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ |
304 | } while (0) | | 304 | } while (0) |
305 | | | 305 | |
306 | #endif /* __XEN_PUBLIC_IO_RING_H__ */ | | 306 | #endif /* __XEN_PUBLIC_IO_RING_H__ */ |
307 | | | 307 | |
308 | /* | | 308 | /* |
309 | * Local variables: | | 309 | * Local variables: |
310 | * mode: C | | 310 | * mode: C |
311 | * c-set-style: "BSD" | | 311 | * c-set-style: "BSD" |
312 | * c-basic-offset: 4 | | 312 | * c-basic-offset: 4 |
313 | * tab-width: 4 | | 313 | * tab-width: 4 |
314 | * indent-tabs-mode: nil | | 314 | * indent-tabs-mode: nil |
315 | * End: | | 315 | * End: |
316 | */ | | 316 | */ |