FD.io VPP  v20.01-46-g7006026de
Vector Packet Processing
lock.h
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1 /*
2  * Copyright (c) 2017 Cisco and/or its affiliates.
3  * Licensed under the Apache License, Version 2.0 (the "License");
4  * you may not use this file except in compliance with the License.
5  * You may obtain a copy of the License at:
6  *
7  * http://www.apache.org/licenses/LICENSE-2.0
8  *
9  * Unless required by applicable law or agreed to in writing, software
10  * distributed under the License is distributed on an "AS IS" BASIS,
11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12  * See the License for the specific language governing permissions and
13  * limitations under the License.
14  */
15 
16 #ifndef included_clib_lock_h
17 #define included_clib_lock_h
18 
19 #include <vppinfra/clib.h>
20 #include <vppinfra/atomics.h>
21 
22 #if __x86_64__
23 #define CLIB_PAUSE() __builtin_ia32_pause ()
24 #elif defined (__aarch64__) || defined (__arm__)
25 #define CLIB_PAUSE() __asm__ ("yield")
26 #else
27 #define CLIB_PAUSE()
28 #endif
29 
30 #if CLIB_DEBUG > 1
31 #define CLIB_LOCK_DBG(_p) \
32 do { \
33  (*_p)->frame_address = __builtin_frame_address (0); \
34  (*_p)->pid = getpid (); \
35  (*_p)->thread_index = os_get_thread_index (); \
36 } while (0)
37 #define CLIB_LOCK_DBG_CLEAR(_p) \
38 do { \
39  (*_p)->frame_address = 0; \
40  (*_p)->pid = 0; \
41  (*_p)->thread_index = 0; \
42 } while (0)
43 #else
44 #define CLIB_LOCK_DBG(_p)
45 #define CLIB_LOCK_DBG_CLEAR(_p)
46 #endif
47 
48 #define CLIB_SPINLOCK_IS_LOCKED(_p) (*(_p))->lock
49 #define CLIB_SPINLOCK_ASSERT_LOCKED(_p) ASSERT(CLIB_SPINLOCK_IS_LOCKED((_p)))
50 
51 typedef struct
52 {
53  CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
55 #if CLIB_DEBUG > 0
56  pid_t pid;
59 #endif
61 
62 static inline void
64 {
66  clib_memset ((void *) *p, 0, CLIB_CACHE_LINE_BYTES);
67 }
68 
69 static inline void
71 {
72  if (*p)
73  {
74  clib_mem_free ((void *) *p);
75  *p = 0;
76  }
77 }
78 
81 {
82  u32 free = 0;
83  while (!clib_atomic_cmp_and_swap_acq_relax_n (&(*p)->lock, &free, 1, 0))
84  {
85  /* atomic load limits number of compare_exchange executions */
86  while (clib_atomic_load_relax_n (&(*p)->lock))
87  CLIB_PAUSE ();
88  /* on failure, compare_exchange writes (*p)->lock into free */
89  free = 0;
90  }
91  CLIB_LOCK_DBG (p);
92 }
93 
96 {
97  if (PREDICT_FALSE (*p != 0))
99 }
100 
103 {
105  /* Make sure all reads/writes are complete before releasing the lock */
106  clib_atomic_release (&(*p)->lock);
107 }
108 
111 {
112  if (PREDICT_FALSE (*p != 0))
114 }
115 
116 /*
117  * Readers-Writer Lock
118  */
119 
120 typedef struct clib_rw_lock_
121 {
122  CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
123  /* -1 when W lock held, > 0 when R lock held */
124  volatile i32 rw_cnt;
125 #if CLIB_DEBUG > 0
126  pid_t pid;
129 #endif
130 } *clib_rwlock_t;
131 
132 always_inline void
134 {
136  clib_memset ((void *) *p, 0, CLIB_CACHE_LINE_BYTES);
137 }
138 
139 always_inline void
141 {
142  if (*p)
143  {
144  clib_mem_free ((void *) *p);
145  *p = 0;
146  }
147 }
148 
149 always_inline void
151 {
152  i32 cnt;
153  do
154  {
155  /* rwlock held by a writer */
156  while ((cnt = clib_atomic_load_relax_n (&(*p)->rw_cnt)) < 0)
157  CLIB_PAUSE ();
158  }
160  (&(*p)->rw_cnt, &cnt, cnt + 1, 1));
161  CLIB_LOCK_DBG (p);
162 }
163 
164 always_inline void
166 {
167  ASSERT ((*p)->rw_cnt > 0);
169  clib_atomic_fetch_sub_rel (&(*p)->rw_cnt, 1);
170 }
171 
172 always_inline void
174 {
175  i32 cnt = 0;
176  do
177  {
178  /* rwlock held by writer or reader(s) */
179  while ((cnt = clib_atomic_load_relax_n (&(*p)->rw_cnt)) != 0)
180  CLIB_PAUSE ();
181  }
182  while (!clib_atomic_cmp_and_swap_acq_relax_n (&(*p)->rw_cnt, &cnt, -1, 1));
183  CLIB_LOCK_DBG (p);
184 }
185 
186 always_inline void
188 {
190  clib_atomic_release (&(*p)->rw_cnt);
191 }
192 
193 #endif
194 
195 /*
196  * fd.io coding-style-patch-verification: ON
197  *
198  * Local Variables:
199  * eval: (c-set-style "gnu")
200  * End:
201  */
static void clib_rwlock_reader_lock(clib_rwlock_t *p)
Definition: lock.h:150
uword thread_index
Definition: lock.h:57
#define CLIB_PAUSE()
Definition: lock.h:23
#define CLIB_CACHE_LINE_ALIGN_MARK(mark)
Definition: cache.h:60
static_always_inline void clib_spinlock_unlock(clib_spinlock_t *p)
Definition: lock.h:102
static_always_inline void clib_spinlock_lock(clib_spinlock_t *p)
Definition: lock.h:80
static void clib_rwlock_writer_lock(clib_rwlock_t *p)
Definition: lock.h:173
CLIB_CACHE_LINE_ALIGN_MARK(cacheline0)
clib_memset(h->entries, 0, sizeof(h->entries[0]) *entries)
static void clib_rwlock_free(clib_rwlock_t *p)
Definition: lock.h:140
static_always_inline void clib_spinlock_unlock_if_init(clib_spinlock_t *p)
Definition: lock.h:110
pid_t pid
Definition: lock.h:126
void * frame_address
Definition: lock.h:128
static void clib_spinlock_free(clib_spinlock_t *p)
Definition: lock.h:70
#define CLIB_LOCK_DBG_CLEAR(_p)
Definition: lock.h:45
#define static_always_inline
Definition: clib.h:99
unsigned int u32
Definition: types.h:88
uword thread_index
Definition: lock.h:127
u32 lock
Definition: lock.h:54
static void clib_spinlock_init(clib_spinlock_t *p)
Definition: lock.h:63
static void clib_rwlock_init(clib_rwlock_t *p)
Definition: lock.h:133
#define clib_atomic_release(a)
Definition: atomics.h:43
static void clib_rwlock_reader_unlock(clib_rwlock_t *p)
Definition: lock.h:165
#define PREDICT_FALSE(x)
Definition: clib.h:111
#define always_inline
Definition: ipsec.h:28
static void clib_rwlock_writer_unlock(clib_rwlock_t *p)
Definition: lock.h:187
pid_t pid
Definition: lock.h:56
struct clib_rw_lock_ * clib_rwlock_t
#define clib_atomic_load_relax_n(a)
Definition: atomics.h:47
signed int i32
Definition: types.h:77
#define ASSERT(truth)
static void clib_mem_free(void *p)
Definition: mem.h:226
volatile i32 rw_cnt
Definition: lock.h:124
#define clib_atomic_fetch_sub_rel(a, b)
Definition: atomics.h:55
u64 uword
Definition: types.h:112
#define clib_atomic_cmp_and_swap_acq_relax_n(addr, exp, new, weak)
Definition: atomics.h:40
static void * clib_mem_alloc_aligned(uword size, uword align)
Definition: mem.h:161
void * frame_address
Definition: lock.h:58
#define CLIB_CACHE_LINE_BYTES
Definition: cache.h:59
static_always_inline void clib_spinlock_lock_if_init(clib_spinlock_t *p)
Definition: lock.h:95
#define CLIB_LOCK_DBG(_p)
Definition: lock.h:44