X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=src%2Fvppinfra%2Flock.h;h=dd79c40b7f277890da31ccd9da15f7eed7b1df4c;hb=a332c46a51f9b4e13963340dfee1318e7513c124;hp=0ffb0455be051a780be017dfe086fa056f50a83c;hpb=e71eb5922a293eca36dbd323970741daaca3c5c7;p=vpp.git

diff --git a/src/vppinfra/lock.h b/src/vppinfra/lock.h
index 0ffb0455be0..dd79c40b7f2 100644
--- a/src/vppinfra/lock.h
+++ b/src/vppinfra/lock.h
@@ -109,6 +109,7 @@ typedef struct clib_rw_lock_
 {
   CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
   volatile u32 n_readers;
+  volatile u32 n_readers_lock;
   volatile u32 writer_lock;
 #if CLIB_DEBUG > 0
   pid_t pid;
@@ -137,23 +138,39 @@ clib_rwlock_free (clib_rwlock_t * p)
 always_inline void
 clib_rwlock_reader_lock (clib_rwlock_t * p)
 {
-  if (__sync_fetch_and_add (&(*p)->n_readers, 1) == 0)
+  while (__sync_lock_test_and_set (&(*p)->n_readers_lock, 1))
+    CLIB_PAUSE ();
+
+  (*p)->n_readers += 1;
+  if ((*p)->n_readers == 1)
     {
       while (__sync_lock_test_and_set (&(*p)->writer_lock, 1))
 	CLIB_PAUSE ();
     }
+  CLIB_MEMORY_BARRIER ();
+  (*p)->n_readers_lock = 0;
+
   CLIB_LOCK_DBG (p);
 }
 
 always_inline void
 clib_rwlock_reader_unlock (clib_rwlock_t * p)
 {
+  ASSERT ((*p)->n_readers > 0);
   CLIB_LOCK_DBG_CLEAR (p);
-  if (__sync_fetch_and_sub (&(*p)->n_readers, 1) == 1)
+
+  while (__sync_lock_test_and_set (&(*p)->n_readers_lock, 1))
+    CLIB_PAUSE ();
+
+  (*p)->n_readers -= 1;
+  if ((*p)->n_readers == 0)
     {
       CLIB_MEMORY_BARRIER ();
       (*p)->writer_lock = 0;
     }
+
+  CLIB_MEMORY_BARRIER ();
+  (*p)->n_readers_lock = 0;
 }
 
 always_inline void