From 2cbe46b506cc2e8bc6304b6632443650d0c3be6a Mon Sep 17 00:00:00 2001
From: Massimiliano Pinto <massimiliano.pinto@skysql.com>
Date: Thu, 24 Oct 2013 17:53:38 +0200
Subject: [PATCH] gwbuf_consume is protected by spinlock

---
 server/core/dcb.c                       |  4 +++-
 server/modules/protocol/mysql_backend.c | 15 +++++++++++++--
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/server/core/dcb.c b/server/core/dcb.c
index f87f05750..ad19ea517 100644
--- a/server/core/dcb.c
+++ b/server/core/dcb.c
@@ -760,7 +760,6 @@ dcb_write(DCB *dcb, GWBUF *queue)
 			dcb->stats.n_buffered++;
 		}
 	} /* if (dcb->writeq) */
-	spinlock_release(&dcb->writeqlock);
 
 	if (saved_errno != 0 &&
             queue != NULL &&
@@ -774,8 +773,11 @@ dcb_write(DCB *dcb, GWBUF *queue)
                         dcb_isclient(dcb) ? "client" : "backend server",
                         saved_errno,
                         strerror(saved_errno));
+
+		spinlock_release(&dcb->writeqlock);
 		return 0;
 	}
+	spinlock_release(&dcb->writeqlock);
 	return 1;
 }
 
diff --git a/server/modules/protocol/mysql_backend.c b/server/modules/protocol/mysql_backend.c
index e1d8a9bf9..bf4fa4c77 100644
--- a/server/modules/protocol/mysql_backend.c
+++ b/server/modules/protocol/mysql_backend.c
@@ -258,7 +258,8 @@ static int gw_read_backend_event(DCB *dcb) {
 
                 if (backend_protocol->state == MYSQL_AUTH_FAILED) {
                         /* check the delayq before the reply */
-                        if (dcb->delayq) {
+			spinlock_acquire(&dcb->authlock);
+                        if (dcb->delayq != NULL) {
                                 /* send an error to the client */
                                 mysql_send_custom_error(
                                         dcb->session->client,
@@ -268,6 +269,8 @@ static int gw_read_backend_event(DCB *dcb) {
 				// consume all the delay queue
 				dcb->delayq = gwbuf_consume(dcb->delayq, gwbuf_length(dcb->delayq));
                         }
+			spinlock_release(&dcb->authlock);
+
                         /**
                          * Protect call of closeSession.
                          */
@@ -473,6 +476,7 @@ gw_MySQLWrite_backend(DCB *dcb, GWBUF *queue)
         /**
          * Don't write to backend if backend_dcb is not in poll set anymore.
          */
+	spinlock_acquire(&dcb->authlock);
         if (dcb->state != DCB_STATE_POLLING) {
                 /** Free buffer memory */
                 gwbuf_consume(queue, GWBUF_LENGTH(queue));
@@ -485,9 +489,11 @@ gw_MySQLWrite_backend(DCB *dcb, GWBUF *queue)
                         dcb,
                         dcb->fd,
                         STRDCBSTATE(dcb->state));
+
+		spinlock_release(&dcb->authlock);
                 return 0;
         }
-	spinlock_acquire(&dcb->authlock);
+
 	/**
 	 * Now put the incoming data to the delay queue unless backend is
          * connected with auth ok
@@ -849,8 +855,13 @@ static int gw_change_user(DCB *backend, SERVER *server, SESSION *in_session, GWB
 	}
 	
 	// consume all the data received from client
+
+	spinlock_acquire(&backend->writeqlock);
+
 	len = gwbuf_length(queue);
 	queue = gwbuf_consume(queue, len);
+	
+	spinlock_release(&backend->writeqlock);
 
 	return rv;
 }