ovs-thread: Add pthread spin lock support.

The patch adds the basic spin lock functions:
ovs_spin_{lock, try_lock, unlock, init, destroy}.
OSX does not support pthread spin lock, so make it
linux only.

Signed-off-by: William Tu <u9012063@gmail.com>
Signed-off-by: 0-day Robot <robot@bytheb.org>

include/openvswitch/thread.h

@@ -33,6 +33,13 @@ struct OVS_LOCKABLE ovs_mutex {
     const char *where;          /* NULL if and only if uninitialized. */
 };
 
+#ifdef __linux__
+struct OVS_LOCKABLE ovs_spin {
+    pthread_spinlock_t lock;
+    const char *where;          /* NULL if and only if uninitialized. */
+};
+#endif
+
 /* "struct ovs_mutex" initializer. */
 #ifdef PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP
 #define OVS_MUTEX_INITIALIZER { PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP, \
@@ -70,6 +77,21 @@ int ovs_mutex_trylock_at(const struct ovs_mutex *mutex, const char *where)
 
 void ovs_mutex_cond_wait(pthread_cond_t *, const struct ovs_mutex *mutex)
     OVS_REQUIRES(mutex);
+
+#ifdef __linux__
+void ovs_spin_init(const struct ovs_spin *);
+void ovs_spin_destroy(const struct ovs_spin *);
+void ovs_spin_unlock(const struct ovs_spin *spin) OVS_RELEASES(spin);
+void ovs_spin_lock_at(const struct ovs_spin *spin, const char *where)
+    OVS_ACQUIRES(spin);
+#define ovs_spin_lock(spin) \
+        ovs_spin_lock_at(spin, OVS_SOURCE_LOCATOR)
+
+int ovs_spin_trylock_at(const struct ovs_spin *spin, const char *where)
+    OVS_TRY_LOCK(0, spin);
+#define ovs_spin_trylock(spin) \
+        ovs_spin_trylock_at(spin, OVS_SOURCE_LOCATOR)
+#endif
 
 /* Convenient once-only execution.
  *

lib/ovs-thread.c

@@ -75,6 +75,9 @@ static bool multithreaded;
 LOCK_FUNCTION(mutex, lock);
 LOCK_FUNCTION(rwlock, rdlock);
 LOCK_FUNCTION(rwlock, wrlock);
+#ifdef __linux__
+LOCK_FUNCTION(spin, lock);
+#endif
 
 #define TRY_LOCK_FUNCTION(TYPE, FUN) \
     int \
@@ -103,6 +106,9 @@ LOCK_FUNCTION(rwlock, wrlock);
 TRY_LOCK_FUNCTION(mutex, trylock);
 TRY_LOCK_FUNCTION(rwlock, tryrdlock);
 TRY_LOCK_FUNCTION(rwlock, trywrlock);
+#ifdef __linux__
+TRY_LOCK_FUNCTION(spin, trylock);
+#endif
 
 #define UNLOCK_FUNCTION(TYPE, FUN, WHERE) \
     void \
@@ -125,6 +131,10 @@ UNLOCK_FUNCTION(mutex, unlock, "<unlocked>");
 UNLOCK_FUNCTION(mutex, destroy, NULL);
 UNLOCK_FUNCTION(rwlock, unlock, "<unlocked>");
 UNLOCK_FUNCTION(rwlock, destroy, NULL);
+#ifdef __linux__
+UNLOCK_FUNCTION(spin, unlock, "<unlocked>");
+UNLOCK_FUNCTION(spin, destroy, NULL);
+#endif
 
 #define XPTHREAD_FUNC1(FUNCTION, PARAM1)                \
     void                                                \
@@ -268,6 +278,27 @@ ovs_mutex_cond_wait(pthread_cond_t *cond, const struct ovs_mutex *mutex_)
     }
 }
 
+#ifdef __linux__
+static void
+ovs_spin_init__(const struct ovs_spin *l_, int pshared)
+{
+    struct ovs_spin *l = CONST_CAST(struct ovs_spin *, l_);
+    int error;
+
+    l->where = "<unlocked>";
+    error = pthread_spin_init(&l->lock, pshared);
+    if (OVS_UNLIKELY(error)) {
+        ovs_abort(error, "pthread_spin_failed");
+    }
+}
+
+void
+ovs_spin_init(const struct ovs_spin *spin)
+{
+    ovs_spin_init__(spin, PTHREAD_PROCESS_PRIVATE);
+}
+#endif
+
 /* Initializes the 'barrier'.  'size' is the number of threads
  * expected to hit the barrier. */
 void