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