ck_{rw,byte,br}lock: Serialize final loads with respect to read.

I will switch to a SPARC-style barrier interface.

include/ck_brlock.h

@@ -198,6 +198,7 @@ ck_brlock_read_lock(struct ck_brlock *br, struct ck_brlock_reader *reader)
 		ck_pr_store_uint(&reader->n_readers, 0);
 	}
 
+	ck_pr_fence_load();
 	return;
 }
 
@@ -235,6 +236,7 @@ ck_brlock_read_trylock(struct ck_brlock *br,
 			return false;
 	}
 
+	ck_pr_fence_load();
 	return true;
 }
 

include/ck_bytelock.h

@@ -143,6 +143,7 @@ ck_bytelock_read_lock(struct ck_bytelock *bytelock, unsigned int slot)
 				ck_pr_stall();
 		}
 
+		ck_pr_fence_load();
 		return;
 	}
 

include/ck_rwlock.h

@@ -113,6 +113,7 @@ ck_rwlock_read_trylock(ck_rwlock_t *rw)
 	return false;
 
 leave:
+	ck_pr_fence_load();
 	return true;
 }
 
@@ -131,6 +132,7 @@ ck_rwlock_read_lock(ck_rwlock_t *rw)
 		ck_pr_dec_uint(&rw->n_readers);
 	}
 
+	ck_pr_fence_load();
 	return;
 }