protocol/server: Remove connection from conf->conns w.o. race

1) Adding the connection to conf->conns used to
happen in conf->mutex, but removing happened under conn->lock.
Fixed that as below.
When the connection object is created conn's ref, bind_ref count
is set to '1'. For bind_ref ref/unref happens under conf->mutex
whenever server_connection_get, put is called.
When bind_ref goes to '0' connection object is removed from
conf->conns under conf->mutex.  After it is removed from the list,
conn_unref is called outside the conf->mutex.
conn_ref/unref still happens under conn->lock.

2) Fixed races in server_connection_cleaup in grace_timer_handler
and server_setvolume.

Change-Id: Ie7b63b10f658af909a11c3327066667f5b7bd114
BUG: 801675
Signed-off-by: Pranith Kumar K <pranithk@gluster.com>
Reviewed-on: http://review.gluster.com/2911
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Amar Tumballi <amarts@redhat.com>
Reviewed-by: Vijay Bellur <vijay@gluster.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/xlators/protocol/server/src/server-handshake.c b/xlators/protocol/server/src/server-handshake.c
index d1e3659ab..ba80185fe 100644
--- a/xlators/protocol/server/src/server-handshake.c
+++ b/xlators/protocol/server/src/server-handshake.c
@@ -432,8 +432,8 @@ server_setvolume (rpcsvc_request_t *req)
         }
 
         cancelled = server_cancel_conn_timer (this, conn);
-        if (cancelled)
-                server_conn_unref (conn);
+        if (cancelled)//Do connection_put on behalf of grace-timer-handler.
+                server_connection_put (this, conn, NULL);
         if (conn->lk_version != 0 &&
             conn->lk_version != lk_version) {
                 (void) server_connection_cleanup (this, conn);
@@ -723,7 +723,7 @@ server_set_lk_version (rpcsvc_request_t *req)
 
         conn = server_connection_get (this, args.uid);
         conn->lk_version = args.lk_ver;
-        server_conn_unref (conn);
+        server_connection_put (this, conn, NULL);
 
         rsp.lk_ver   = args.lk_ver;