ovs-thread: New module, initially just with pthreads wrapper functions.

The only tricky part here is that I'm throwing in annotations to allow
"sparse" to report unbalanced locking.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>

include/sparse/pthread.h

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2013 Nicira, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __CHECKER__
+#error "Use this header only with sparse.  It is not a correct implementation."
+#endif
+
+/* Get actual <pthread.h> definitions for us to annotate and build on. */
+#include_next <pthread.h>
+
+#include "compiler.h"
+
+int pthread_mutex_lock(pthread_mutex_t *mutex) OVS_ACQUIRES(mutex);
+int pthread_mutex_unlock(pthread_mutex_t *mutex) OVS_RELEASES(mutex);
+
+int pthread_rwlock_rdlock(pthread_rwlock_t *rwlock) OVS_ACQUIRES(rwlock);
+int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock) OVS_ACQUIRES(rwlock);
+int pthread_rwlock_unlock(pthread_rwlock_t *rwlock) OVS_RELEASES(rwlock);
+
+int pthread_cond_wait(pthread_cond_t *, pthread_mutex_t *mutex)
+    OVS_MUST_HOLD(mutex);
+
+#define pthread_mutex_trylock(MUTEX)                    \
+    ({                                                  \
+        int retval = pthread_mutex_trylock(mutex);      \
+        if (!retval) {                                  \
+            OVS_ACQUIRE(MUTEX);                         \
+        }                                               \
+        retval;                                         \
+    })
+
+#define pthread_rwlock_tryrdlock(RWLOCK)                \
+    ({                                                  \
+        int retval = pthread_rwlock_tryrdlock(rwlock);  \
+        if (!retval) {                                  \
+            OVS_ACQUIRE(RWLOCK);                        \
+        }                                               \
+        retval;                                         \
+    })
+#define pthread_rwlock_trywrlock(RWLOCK)                \
+    ({                                                  \
+        int retval = pthread_rwlock_trywrlock(rwlock);  \
+        if (!retval) {                                  \
+            OVS_ACQUIRE(RWLOCK);                        \
+        }                                               \
+        retval;                                         \
+    })