[ovs-dev] [PATCHv17 1/2] ovs-thread: Add pthread spin lock support.

[William Tu]

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 at gmail.com>
---
 configure.ac                 |  1 +
 include/openvswitch/thread.h | 24 ++++++++++++++++++++++++
 lib/ovs-thread.c             | 31 +++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+)

diff --git a/configure.ac b/configure.ac
index a9f0a06dc140..dd2a674af0c9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -108,6 +108,7 @@ AC_CHECK_MEMBERS([struct sockaddr_in6.sin6_scope_id], [], [],
 #include <sys/types.h>
 #include <netinet/in.h>]])
 AC_CHECK_FUNCS([mlockall strnlen getloadavg statvfs getmntent_r sendmmsg clock_gettime])
+AC_CHECK_FUNCS([pthread_spin_lock])
 AC_CHECK_HEADERS([mntent.h sys/statvfs.h linux/types.h linux/if_ether.h])
 AC_CHECK_HEADERS([linux/net_namespace.h stdatomic.h bits/floatn-common.h])
 AC_CHECK_HEADERS([net/if_mib.h], [], [], [[#include <sys/types.h>
diff --git a/include/openvswitch/thread.h b/include/openvswitch/thread.h
index 2987db37c9dc..b07b7167b303 100644
--- a/include/openvswitch/thread.h
+++ b/include/openvswitch/thread.h
@@ -17,6 +17,8 @@
 #ifndef OPENVSWITCH_THREAD_H
 #define OPENVSWITCH_THREAD_H 1
 
+#include <config.h>
+
 #include <pthread.h>
 #include <stddef.h>
 #include <stdbool.h>
@@ -33,6 +35,13 @@ struct OVS_LOCKABLE ovs_mutex {
     const char *where;          /* NULL if and only if uninitialized. */
 };
 
+#ifdef HAVE_PTHREAD_SPIN_LOCK
+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 +79,21 @@ 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 HAVE_PTHREAD_SPIN_LOCK
+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.
  *
diff --git a/lib/ovs-thread.c b/lib/ovs-thread.c
index 159d87e5b0ca..b686e4548127 100644
--- a/lib/ovs-thread.c
+++ b/lib/ovs-thread.c
@@ -75,6 +75,9 @@ static bool multithreaded;
 LOCK_FUNCTION(mutex, lock);
 LOCK_FUNCTION(rwlock, rdlock);
 LOCK_FUNCTION(rwlock, wrlock);
+#ifdef HAVE_PTHREAD_SPIN_LOCK
+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 HAVE_PTHREAD_SPIN_LOCK
+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 HAVE_PTHREAD_SPIN_LOCK
+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 HAVE_PTHREAD_SPIN_LOCK
+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_init 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
-- 
2.7.4