include/qemu/thread.h

   1 #ifndef QEMU_THREAD_H
   2 #define QEMU_THREAD_H
   3
   4 #include "qemu/processor.h"
   5 #include "qemu/atomic.h"
   6
   7 typedef struct QemuCond QemuCond;
   8 typedef struct QemuSemaphore QemuSemaphore;
   9 typedef struct QemuEvent QemuEvent;
  10 typedef struct QemuLockCnt QemuLockCnt;
  11 typedef struct QemuThread QemuThread;
  12
  13 #ifdef _WIN32
  14 #include "qemu/thread-win32.h"
  15 #else
  16 #include "qemu/thread-posix.h"
  17 #endif
  18
  19 #define QEMU_THREAD_JOINABLE 0
  20 #define QEMU_THREAD_DETACHED 1
  21
  22 void qemu_mutex_init(QemuMutex *mutex);
  23 void qemu_mutex_destroy(QemuMutex *mutex);
  24 int qemu_mutex_trylock_impl(QemuMutex *mutex, const char *file, const int line);
  25 void qemu_mutex_lock_impl(QemuMutex *mutex, const char *file, const int line);
  26 void qemu_mutex_unlock_impl(QemuMutex *mutex, const char *file, const int line);
  27
  28 #define qemu_mutex_lock(mutex) \
  29         qemu_mutex_lock_impl(mutex, __FILE__, __LINE__)
  30 #define qemu_mutex_trylock(mutex) \
  31         qemu_mutex_trylock_impl(mutex, __FILE__, __LINE__)
  32 #define qemu_mutex_unlock(mutex) \
  33         qemu_mutex_unlock_impl(mutex, __FILE__, __LINE__)
  34
  35 static inline void (qemu_mutex_lock)(QemuMutex *mutex)
  36 {
  37     qemu_mutex_lock(mutex);
  38 }
  39
  40 static inline int (qemu_mutex_trylock)(QemuMutex *mutex)
  41 {
  42     return qemu_mutex_trylock(mutex);
  43 }
  44
  45 static inline void (qemu_mutex_unlock)(QemuMutex *mutex)
  46 {
  47     qemu_mutex_unlock(mutex);
  48 }
  49
  50 /* Prototypes for other functions are in thread-posix.h/thread-win32.h.  */
  51 void qemu_rec_mutex_init(QemuRecMutex *mutex);
  52
  53 void qemu_cond_init(QemuCond *cond);
  54 void qemu_cond_destroy(QemuCond *cond);
  55
  56 /*
  57  * IMPORTANT: The implementation does not guarantee that pthread_cond_signal
  58  * and pthread_cond_broadcast can be called except while the same mutex is
  59  * held as in the corresponding pthread_cond_wait calls!
  60  */
  61 void qemu_cond_signal(QemuCond *cond);
  62 void qemu_cond_broadcast(QemuCond *cond);
  63 void qemu_cond_wait_impl(QemuCond *cond, QemuMutex *mutex,
  64                          const char *file, const int line);
  65
  66 #define qemu_cond_wait(cond, mutex) \
  67         qemu_cond_wait_impl(cond, mutex, __FILE__, __LINE__)
  68
  69 static inline void (qemu_cond_wait)(QemuCond *cond, QemuMutex *mutex)
  70 {
  71     qemu_cond_wait(cond, mutex);
  72 }
  73
  74 void qemu_sem_init(QemuSemaphore *sem, int init);
  75 void qemu_sem_post(QemuSemaphore *sem);
  76 void qemu_sem_wait(QemuSemaphore *sem);
  77 int qemu_sem_timedwait(QemuSemaphore *sem, int ms);
  78 void qemu_sem_destroy(QemuSemaphore *sem);
  79
  80 void qemu_event_init(QemuEvent *ev, bool init);
  81 void qemu_event_set(QemuEvent *ev);
  82 void qemu_event_reset(QemuEvent *ev);
  83 void qemu_event_wait(QemuEvent *ev);
  84 void qemu_event_destroy(QemuEvent *ev);
  85
  86 void qemu_thread_create(QemuThread *thread, const char *name,
  87                         void *(*start_routine)(void *),
  88                         void *arg, int mode);
  89 void *qemu_thread_join(QemuThread *thread);
  90 void qemu_thread_get_self(QemuThread *thread);
  91 bool qemu_thread_is_self(QemuThread *thread);
  92 void qemu_thread_exit(void *retval);
  93 void qemu_thread_naming(bool enable);
  94
  95 struct Notifier;
  96 void qemu_thread_atexit_add(struct Notifier *notifier);
  97 void qemu_thread_atexit_remove(struct Notifier *notifier);
  98
  99 struct QemuSpin {
 100     int value;
 101 };
 102
 103 static inline void qemu_spin_init(QemuSpin *spin)
 104 {
 105     __sync_lock_release(&spin->value);
 106 }
 107
 108 static inline void qemu_spin_lock(QemuSpin *spin)
 109 {
 110     while (unlikely(__sync_lock_test_and_set(&spin->value, true))) {
 111         while (atomic_read(&spin->value)) {
 112             cpu_relax();
 113         }
 114     }
 115 }
 116
 117 static inline bool qemu_spin_trylock(QemuSpin *spin)
 118 {
 119     return __sync_lock_test_and_set(&spin->value, true);
 120 }
 121
 122 static inline bool qemu_spin_locked(QemuSpin *spin)
 123 {
 124     return atomic_read(&spin->value);
 125 }
 126
 127 static inline void qemu_spin_unlock(QemuSpin *spin)
 128 {
 129     __sync_lock_release(&spin->value);
 130 }
 131
 132 struct QemuLockCnt {
 133 #ifndef CONFIG_LINUX
 134     QemuMutex mutex;
 135 #endif
 136     unsigned count;
 137 };
 138
 139 /**
 140  * qemu_lockcnt_init: initialize a QemuLockcnt
 141  * @lockcnt: the lockcnt to initialize
 142  *
 143  * Initialize lockcnt's counter to zero and prepare its mutex
 144  * for usage.
 145  */
 146 void qemu_lockcnt_init(QemuLockCnt *lockcnt);
 147
 148 /**
 149  * qemu_lockcnt_destroy: destroy a QemuLockcnt
 150  * @lockcnt: the lockcnt to destruct
 151  *
 152  * Destroy lockcnt's mutex.
 153  */
 154 void qemu_lockcnt_destroy(QemuLockCnt *lockcnt);
 155
 156 /**
 157  * qemu_lockcnt_inc: increment a QemuLockCnt's counter
 158  * @lockcnt: the lockcnt to operate on
 159  *
 160  * If the lockcnt's count is zero, wait for critical sections
 161  * to finish and increment lockcnt's count to 1.  If the count
 162  * is not zero, just increment it.
 163  *
 164  * Because this function can wait on the mutex, it must not be
 165  * called while the lockcnt's mutex is held by the current thread.
 166  * For the same reason, qemu_lockcnt_inc can also contribute to
 167  * AB-BA deadlocks.  This is a sample deadlock scenario:
 168  *
 169  *            thread 1                      thread 2
 170  *            -------------------------------------------------------
 171  *            qemu_lockcnt_lock(&lc1);
 172  *                                          qemu_lockcnt_lock(&lc2);
 173  *            qemu_lockcnt_inc(&lc2);
 174  *                                          qemu_lockcnt_inc(&lc1);
 175  */
 176 void qemu_lockcnt_inc(QemuLockCnt *lockcnt);
 177
 178 /**
 179  * qemu_lockcnt_dec: decrement a QemuLockCnt's counter
 180  * @lockcnt: the lockcnt to operate on
 181  */
 182 void qemu_lockcnt_dec(QemuLockCnt *lockcnt);
 183
 184 /**
 185  * qemu_lockcnt_dec_and_lock: decrement a QemuLockCnt's counter and
 186  * possibly lock it.
 187  * @lockcnt: the lockcnt to operate on
 188  *
 189  * Decrement lockcnt's count.  If the new count is zero, lock
 190  * the mutex and return true.  Otherwise, return false.
 191  */
 192 bool qemu_lockcnt_dec_and_lock(QemuLockCnt *lockcnt);
 193
 194 /**
 195  * qemu_lockcnt_dec_if_lock: possibly decrement a QemuLockCnt's counter and
 196  * lock it.
 197  * @lockcnt: the lockcnt to operate on
 198  *
 199  * If the count is 1, decrement the count to zero, lock
 200  * the mutex and return true.  Otherwise, return false.
 201  */
 202 bool qemu_lockcnt_dec_if_lock(QemuLockCnt *lockcnt);
 203
 204 /**
 205  * qemu_lockcnt_lock: lock a QemuLockCnt's mutex.
 206  * @lockcnt: the lockcnt to operate on
 207  *
 208  * Remember that concurrent visits are not blocked unless the count is
 209  * also zero.  You can use qemu_lockcnt_count to check for this inside a
 210  * critical section.
 211  */
 212 void qemu_lockcnt_lock(QemuLockCnt *lockcnt);
 213
 214 /**
 215  * qemu_lockcnt_unlock: release a QemuLockCnt's mutex.
 216  * @lockcnt: the lockcnt to operate on.
 217  */
 218 void qemu_lockcnt_unlock(QemuLockCnt *lockcnt);
 219
 220 /**
 221  * qemu_lockcnt_inc_and_unlock: combined unlock/increment on a QemuLockCnt.
 222  * @lockcnt: the lockcnt to operate on.
 223  *
 224  * This is the same as
 225  *
 226  *     qemu_lockcnt_unlock(lockcnt);
 227  *     qemu_lockcnt_inc(lockcnt);
 228  *
 229  * but more efficient.
 230  */
 231 void qemu_lockcnt_inc_and_unlock(QemuLockCnt *lockcnt);
 232
 233 /**
 234  * qemu_lockcnt_count: query a LockCnt's count.
 235  * @lockcnt: the lockcnt to query.
 236  *
 237  * Note that the count can change at any time.  Still, while the
 238  * lockcnt is locked, one can usefully check whether the count
 239  * is non-zero.
 240  */
 241 unsigned qemu_lockcnt_count(QemuLockCnt *lockcnt);
 242
 243 #endif