ceph/src/seastar/dpdk/lib/librte_eal/common/include/generic/rte_spinlock.h

   1 /*-
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  21  *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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  33
  34 #ifndef _RTE_SPINLOCK_H_
  35 #define _RTE_SPINLOCK_H_
  36
  37 /**
  38  * @file
  39  *
  40  * RTE Spinlocks
  41  *
  42  * This file defines an API for read-write locks, which are implemented
  43  * in an architecture-specific way. This kind of lock simply waits in
  44  * a loop repeatedly checking until the lock becomes available.
  45  *
  46  * All locks must be initialised before use, and only initialised once.
  47  *
  48  */
  49
  50 #include <rte_lcore.h>
  51 #ifdef RTE_FORCE_INTRINSICS
  52 #include <rte_common.h>
  53 #endif
  54
  55 /**
  56  * The rte_spinlock_t type.
  57  */
  58 typedef struct {
  59         volatile int locked; /**< lock status 0 = unlocked, 1 = locked */
  60 } rte_spinlock_t;
  61
  62 /**
  63  * A static spinlock initializer.
  64  */
  65 #define RTE_SPINLOCK_INITIALIZER { 0 }
  66
  67 /**
  68  * Initialize the spinlock to an unlocked state.
  69  *
  70  * @param sl
  71  *   A pointer to the spinlock.
  72  */
  73 static inline void
  74 rte_spinlock_init(rte_spinlock_t *sl)
  75 {
  76         sl->locked = 0;
  77 }
  78
  79 /**
  80  * Take the spinlock.
  81  *
  82  * @param sl
  83  *   A pointer to the spinlock.
  84  */
  85 static inline void
  86 rte_spinlock_lock(rte_spinlock_t *sl);
  87
  88 #ifdef RTE_FORCE_INTRINSICS
  89 static inline void
  90 rte_spinlock_lock(rte_spinlock_t *sl)
  91 {
  92         while (__sync_lock_test_and_set(&sl->locked, 1))
  93                 while(sl->locked)
  94                         rte_pause();
  95 }
  96 #endif
  97
  98 /**
  99  * Release the spinlock.
 100  *
 101  * @param sl
 102  *   A pointer to the spinlock.
 103  */
 104 static inline void
 105 rte_spinlock_unlock (rte_spinlock_t *sl);
 106
 107 #ifdef RTE_FORCE_INTRINSICS
 108 static inline void
 109 rte_spinlock_unlock (rte_spinlock_t *sl)
 110 {
 111         __sync_lock_release(&sl->locked);
 112 }
 113 #endif
 114
 115 /**
 116  * Try to take the lock.
 117  *
 118  * @param sl
 119  *   A pointer to the spinlock.
 120  * @return
 121  *   1 if the lock is successfully taken; 0 otherwise.
 122  */
 123 static inline int
 124 rte_spinlock_trylock (rte_spinlock_t *sl);
 125
 126 #ifdef RTE_FORCE_INTRINSICS
 127 static inline int
 128 rte_spinlock_trylock (rte_spinlock_t *sl)
 129 {
 130         return __sync_lock_test_and_set(&sl->locked,1) == 0;
 131 }
 132 #endif
 133
 134 /**
 135  * Test if the lock is taken.
 136  *
 137  * @param sl
 138  *   A pointer to the spinlock.
 139  * @return
 140  *   1 if the lock is currently taken; 0 otherwise.
 141  */
 142 static inline int rte_spinlock_is_locked (rte_spinlock_t *sl)
 143 {
 144         return sl->locked;
 145 }
 146
 147 /**
 148  * Test if hardware transactional memory (lock elision) is supported
 149  *
 150  * @return
 151  *   1 if the hardware transactional memory is supported; 0 otherwise.
 152  */
 153 static inline int rte_tm_supported(void);
 154
 155 /**
 156  * Try to execute critical section in a hardware memory transaction,
 157  * if it fails or not available take the spinlock.
 158  *
 159  * NOTE: An attempt to perform a HW I/O operation inside a hardware memory
 160  * transaction always aborts the transaction since the CPU is not able to
 161  * roll-back should the transaction fail. Therefore, hardware transactional
 162  * locks are not advised to be used around rte_eth_rx_burst() and
 163  * rte_eth_tx_burst() calls.
 164  *
 165  * @param sl
 166  *   A pointer to the spinlock.
 167  */
 168 static inline void
 169 rte_spinlock_lock_tm(rte_spinlock_t *sl);
 170
 171 /**
 172  * Commit hardware memory transaction or release the spinlock if
 173  * the spinlock is used as a fall-back
 174  *
 175  * @param sl
 176  *   A pointer to the spinlock.
 177  */
 178 static inline void
 179 rte_spinlock_unlock_tm(rte_spinlock_t *sl);
 180
 181 /**
 182  * Try to execute critical section in a hardware memory transaction,
 183  * if it fails or not available try to take the lock.
 184  *
 185  * NOTE: An attempt to perform a HW I/O operation inside a hardware memory
 186  * transaction always aborts the transaction since the CPU is not able to
 187  * roll-back should the transaction fail. Therefore, hardware transactional
 188  * locks are not advised to be used around rte_eth_rx_burst() and
 189  * rte_eth_tx_burst() calls.
 190  *
 191  * @param sl
 192  *   A pointer to the spinlock.
 193  * @return
 194  *   1 if the hardware memory transaction is successfully started
 195  *   or lock is successfully taken; 0 otherwise.
 196  */
 197 static inline int
 198 rte_spinlock_trylock_tm(rte_spinlock_t *sl);
 199
 200 /**
 201  * The rte_spinlock_recursive_t type.
 202  */
 203 typedef struct {
 204         rte_spinlock_t sl; /**< the actual spinlock */
 205         volatile int user; /**< core id using lock, -1 for unused */
 206         volatile int count; /**< count of time this lock has been called */
 207 } rte_spinlock_recursive_t;
 208
 209 /**
 210  * A static recursive spinlock initializer.
 211  */
 212 #define RTE_SPINLOCK_RECURSIVE_INITIALIZER {RTE_SPINLOCK_INITIALIZER, -1, 0}
 213
 214 /**
 215  * Initialize the recursive spinlock to an unlocked state.
 216  *
 217  * @param slr
 218  *   A pointer to the recursive spinlock.
 219  */
 220 static inline void rte_spinlock_recursive_init(rte_spinlock_recursive_t *slr)
 221 {
 222         rte_spinlock_init(&slr->sl);
 223         slr->user = -1;
 224         slr->count = 0;
 225 }
 226
 227 /**
 228  * Take the recursive spinlock.
 229  *
 230  * @param slr
 231  *   A pointer to the recursive spinlock.
 232  */
 233 static inline void rte_spinlock_recursive_lock(rte_spinlock_recursive_t *slr)
 234 {
 235         int id = rte_gettid();
 236
 237         if (slr->user != id) {
 238                 rte_spinlock_lock(&slr->sl);
 239                 slr->user = id;
 240         }
 241         slr->count++;
 242 }
 243 /**
 244  * Release the recursive spinlock.
 245  *
 246  * @param slr
 247  *   A pointer to the recursive spinlock.
 248  */
 249 static inline void rte_spinlock_recursive_unlock(rte_spinlock_recursive_t *slr)
 250 {
 251         if (--(slr->count) == 0) {
 252                 slr->user = -1;
 253                 rte_spinlock_unlock(&slr->sl);
 254         }
 255
 256 }
 257
 258 /**
 259  * Try to take the recursive lock.
 260  *
 261  * @param slr
 262  *   A pointer to the recursive spinlock.
 263  * @return
 264  *   1 if the lock is successfully taken; 0 otherwise.
 265  */
 266 static inline int rte_spinlock_recursive_trylock(rte_spinlock_recursive_t *slr)
 267 {
 268         int id = rte_gettid();
 269
 270         if (slr->user != id) {
 271                 if (rte_spinlock_trylock(&slr->sl) == 0)
 272                         return 0;
 273                 slr->user = id;
 274         }
 275         slr->count++;
 276         return 1;
 277 }
 278
 279
 280 /**
 281  * Try to execute critical section in a hardware memory transaction,
 282  * if it fails or not available take the recursive spinlocks
 283  *
 284  * NOTE: An attempt to perform a HW I/O operation inside a hardware memory
 285  * transaction always aborts the transaction since the CPU is not able to
 286  * roll-back should the transaction fail. Therefore, hardware transactional
 287  * locks are not advised to be used around rte_eth_rx_burst() and
 288  * rte_eth_tx_burst() calls.
 289  *
 290  * @param slr
 291  *   A pointer to the recursive spinlock.
 292  */
 293 static inline void rte_spinlock_recursive_lock_tm(
 294         rte_spinlock_recursive_t *slr);
 295
 296 /**
 297  * Commit hardware memory transaction or release the recursive spinlock
 298  * if the recursive spinlock is used as a fall-back
 299  *
 300  * @param slr
 301  *   A pointer to the recursive spinlock.
 302  */
 303 static inline void rte_spinlock_recursive_unlock_tm(
 304         rte_spinlock_recursive_t *slr);
 305
 306 /**
 307  * Try to execute critical section in a hardware memory transaction,
 308  * if it fails or not available try to take the recursive lock
 309  *
 310  * NOTE: An attempt to perform a HW I/O operation inside a hardware memory
 311  * transaction always aborts the transaction since the CPU is not able to
 312  * roll-back should the transaction fail. Therefore, hardware transactional
 313  * locks are not advised to be used around rte_eth_rx_burst() and
 314  * rte_eth_tx_burst() calls.
 315  *
 316  * @param slr
 317  *   A pointer to the recursive spinlock.
 318  * @return
 319  *   1 if the hardware memory transaction is successfully started
 320  *   or lock is successfully taken; 0 otherwise.
 321  */
 322 static inline int rte_spinlock_recursive_trylock_tm(
 323         rte_spinlock_recursive_t *slr);
 324
 325 #endif /* _RTE_SPINLOCK_H_ */