diff --git a/skynet-src/socket_server.c b/skynet-src/socket_server.c
index 3a23f904..c73a70db 100644
--- a/skynet-src/socket_server.c
+++ b/skynet-src/socket_server.c
@@ -37,9 +37,6 @@
 #define PRIORITY_HIGH 0
 #define PRIORITY_LOW 1
 
-#define DIRECTWRITE_SOCKETTHREAD 1
-#define DIRECTWRITE_WORKERTHREAD 2
-
 #define HASH_ID(id) (((unsigned)id) % MAX_SOCKET)
 
 #define PROTOCOL_TCP 0
@@ -91,7 +88,7 @@ struct socket {
 		int size;
 		uint8_t udp_address[UDP_ADDRESS_SIZE];
 	} p;
-	struct spinlock_nested dw_lock;
+	struct spinlock dw_lock;
 	int dw_offset;
 	const void * dw_buffer;
 	size_t dw_size;
@@ -365,7 +362,7 @@ force_close(struct socket_server *ss, struct socket *s, struct socket_message *r
 	if (s->type != SOCKET_TYPE_PACCEPT && s->type != SOCKET_TYPE_PLISTEN) {
 		sp_del(ss->event_fd, s->fd);
 	}
-	spinlock_nestedlock(&s->dw_lock, DIRECTWRITE_SOCKETTHREAD);
+	spinlock_lock(&s->dw_lock);
 	if (s->type != SOCKET_TYPE_BIND) {
 		if (close(s->fd) < 0) {
 			perror("close socket:");
@@ -376,7 +373,7 @@ force_close(struct socket_server *ss, struct socket *s, struct socket_message *r
 		free_buffer(ss, s->dw_buffer, s->dw_size);
 		s->dw_buffer = NULL;
 	}
-	spinlock_nestedunlock(&s->dw_lock, DIRECTWRITE_SOCKETTHREAD);
+	spinlock_unlock(&s->dw_lock);
 }
 
 void 
@@ -422,7 +419,7 @@ new_fd(struct socket_server *ss, int id, int fd, int protocol, uintptr_t opaque,
 	s->warn_size = 0;
 	check_wb_list(&s->high);
 	check_wb_list(&s->low);
-	spinlock_nestedinit(&s->dw_lock);
+	spinlock_init(&s->dw_lock);
 	s->dw_buffer = NULL;
 	s->dw_size = 0;
 	return s;
@@ -685,7 +682,7 @@ send_buffer_(struct socket_server *ss, struct socket *s, struct socket_message *
 
 static int
 send_buffer(struct socket_server *ss, struct socket *s, struct socket_message *result) {
-	if (!spinlock_nestedtrylock(&s->dw_lock, DIRECTWRITE_SOCKETTHREAD))
+	if (!spinlock_trylock(&s->dw_lock))
 		return -1;	// blocked by direct write, send later.
 	if (s->dw_buffer) {
 		// add direct write buffer before high.head
@@ -706,7 +703,7 @@ send_buffer(struct socket_server *ss, struct socket *s, struct socket_message *r
 		s->dw_buffer = NULL;
 	}
 	int r = send_buffer_(ss,s,result);
-	spinlock_nestedunlock(&s->dw_lock, DIRECTWRITE_SOCKETTHREAD);
+	spinlock_unlock(&s->dw_lock);
 
 	return r;
 }
@@ -1421,7 +1418,7 @@ socket_server_send(struct socket_server *ss, int id, const void * buffer, int sz
 		return -1;
 	}
 
-	if (can_direct_write(s,id) && spinlock_nestedtrylock(&s->dw_lock, DIRECTWRITE_WORKERTHREAD)) {
+	if (can_direct_write(s,id) && spinlock_trylock(&s->dw_lock)) {
 		// may be we can send directly, double check
 		if (can_direct_write(s,id)) {
 			// send directly
@@ -1441,7 +1438,7 @@ socket_server_send(struct socket_server *ss, int id, const void * buffer, int sz
 			}
 			if (n == so.sz) {
 				// write done
-				spinlock_nestedunlock(&s->dw_lock, DIRECTWRITE_WORKERTHREAD);
+				spinlock_unlock(&s->dw_lock);
 				so.free_func((void *)buffer);
 				return 0;
 			}
@@ -1449,14 +1446,12 @@ socket_server_send(struct socket_server *ss, int id, const void * buffer, int sz
 			s->dw_buffer = buffer;
 			s->dw_size = sz;
 			s->dw_offset = n;
+			spinlock_unlock(&s->dw_lock);
 
 			sp_write(ss->event_fd, s->fd, s, true);
-
-			spinlock_nestedunlock(&s->dw_lock, DIRECTWRITE_WORKERTHREAD);
-
 			return 0;
 		}
-		spinlock_nestedunlock(&s->dw_lock, DIRECTWRITE_WORKERTHREAD);
+		spinlock_unlock(&s->dw_lock);
 	}
 
 	struct request_package request;
@@ -1686,7 +1681,7 @@ socket_server_udp_send(struct socket_server *ss, int id, const struct socket_udp
 		return -1;
 	}
 
-	if (can_direct_write(s,id) && spinlock_nestedtrylock(&s->dw_lock, DIRECTWRITE_WORKERTHREAD)) {
+	if (can_direct_write(s,id) && spinlock_trylock(&s->dw_lock)) {
 		// may be we can send directly, double check
 		if (can_direct_write(s,id)) {
 			// send directly
@@ -1697,12 +1692,12 @@ socket_server_udp_send(struct socket_server *ss, int id, const struct socket_udp
 			int n = sendto(s->fd, so.buffer, so.sz, 0, &sa.s, sasz);
 			if (n >= 0) {
 				// sendto succ
-				spinlock_nestedunlock(&s->dw_lock, DIRECTWRITE_WORKERTHREAD);
+				spinlock_unlock(&s->dw_lock);
 				so.free_func((void *)buffer);
 				return 0;
 			}
 		}
-		spinlock_nestedunlock(&s->dw_lock, DIRECTWRITE_WORKERTHREAD);
+		spinlock_unlock(&s->dw_lock);
 		// let socket thread try again, udp doesn't care the order
 	}
 
@@ -1723,13 +1718,13 @@ socket_server_udp_connect(struct socket_server *ss, int id, const char * addr, i
 	if (s->id != id || s->type == SOCKET_TYPE_INVALID) {
 		return -1;
 	}
-	spinlock_nestedlock(&s->dw_lock, DIRECTWRITE_WORKERTHREAD);
+	spinlock_lock(&s->dw_lock);
 	if (s->id != id || s->type == SOCKET_TYPE_INVALID) {
-		spinlock_nestedunlock(&s->dw_lock, DIRECTWRITE_WORKERTHREAD);
+		spinlock_unlock(&s->dw_lock);
 		return -1;
 	}
 	ATOM_INC(&s->udpconnecting);
-	spinlock_nestedunlock(&s->dw_lock, DIRECTWRITE_WORKERTHREAD);
+	spinlock_unlock(&s->dw_lock);
 
 	int status;
 	struct addrinfo ai_hints;
diff --git a/skynet-src/spinlock.h b/skynet-src/spinlock.h
index 98a0bd4b..514546f4 100644
--- a/skynet-src/spinlock.h
+++ b/skynet-src/spinlock.h
@@ -1,8 +1,6 @@
 #ifndef SKYNET_SPINLOCK_H
 #define SKYNET_SPINLOCK_H
 
-#include <assert.h>
-
 #define SPIN_INIT(q) spinlock_init(&(q)->lock);
 #define SPIN_LOCK(q) spinlock_lock(&(q)->lock);
 #define SPIN_UNLOCK(q) spinlock_unlock(&(q)->lock);
@@ -77,63 +75,4 @@ spinlock_destroy(struct spinlock *lock) {
 
 #endif
 
-struct spinlock_nested {
-	struct spinlock lock;
-	int thread;
-	int count;
-};
-
-static inline void
-spinlock_nestedinit(struct spinlock_nested *ln) {
-	spinlock_init(&ln->lock);
-	ln->thread = 0;
-	ln->count = 0;
-}
-
-static inline void
-spinlock_nestedlock(struct spinlock_nested *ln, int thread) {
-	if (thread != ln->thread) {
-		spinlock_lock(&ln->lock);
-		assert(ln->count == 0);
-		ln->thread = thread;
-	}
-	++ln->count;
-}
-
-static inline int
-spinlock_nestedtrylock(struct spinlock_nested *ln, int thread) {
-	if (thread != ln->thread) {
-		if (spinlock_trylock(&ln->lock)) {
-			assert(ln->count == 0);
-			ln->thread = thread;
-			++ln->count;
-			return 1;	// lock succ
-		} else {
-			return 0;
-		}
-	} else {
-		// in the same thread
-		++ln->count;
-		return 1;
-	}
-}
-
-static inline void
-spinlock_nestedunlock(struct spinlock_nested *ln, int thread) {
-	assert(thread == ln->thread);
-	--ln->count;
-	if (ln->count > 0) {
-		return;
-	}
-	assert(ln->count == 0);
-	ln->thread = 0;
-	spinlock_unlock(&ln->lock);
-}
-
-static inline void
-spinlock_nesteddestroy(struct spinlock_nested *ln) {
-	assert(ln->thread == 0 && ln->count == 0);
-	spinlock_destroy(&ln->lock);
-}
-
 #endif