libglusterfs: fix use-after-destroy mutex error

Found with GCC ThreadSanitizer:

WARNING: ThreadSanitizer: use of an invalid mutex (e.g. uninitialized or destroyed) (pid=188590)
    #0 pthread_mutex_lock <null> (libtsan.so.0+0x528ac)
    #1 client_ctx_del /path/to/glusterfs/libglusterfs/src/client_t.c:535 (libglusterfs.so.0+0xc681a)
    #2 client_destroy_cbk /path/to/glusterfs/xlators/protocol/server/src/server.c:944 (server.so+0xaf6e)
    #3 gf_client_destroy_recursive /path/to/glusterfs/libglusterfs/src/client_t.c:295 (libglusterfs.so.0+0xc5058)
    #4 client_destroy /path/to/glusterfs/libglusterfs/src/client_t.c:330 (libglusterfs.so.0+0xc60e4)
    ...

  Location is heap block of size 272 at 0x7b440001a180 allocated by thread T7:
    #0 calloc <null> (libtsan.so.0+0x3075a)
    #1 __gf_calloc /path/to/glusterfs/libglusterfs/src/mem-pool.c:151 (libglusterfs.so.0+0x6e42b)
    #2 gf_client_get /path/to/glusterfs/libglusterfs/src/client_t.c:155 (libglusterfs.so.0+0xc571a)
    ...

The problem is that client_destroy() may call client_ctx_del() (which attempts to lock
'sratch_ctx.lock') via recursive deletion from gf_client_destroy_recursive(), so
destroying mutex before entering recursive deletion is an error. It should be destroyed
later - just before the client context is freed.

Change-Id: I730a628714d2b404e3f019ae552403da16b51b68
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Fixes: #1285

1 files changed, 2 insertions, 2 deletions

diff --git a/libglusterfs/src/client_t.c b/libglusterfs/src/client_t.c
index 4cd22f4920c..9d377c3c2e1 100644
--- a/libglusterfs/src/client_t.c
+++ b/libglusterfs/src/client_t.c
@@ -314,8 +314,6 @@ client_destroy(client_t *client)
 
     clienttable = client->this->ctx->clienttable;
 
-    LOCK_DESTROY(&client->scratch_ctx.lock);
-
     LOCK(&clienttable->lock);
     {
         clienttable->cliententries[client->tbl_index].client = NULL;
@@ -333,6 +331,8 @@ client_destroy(client_t *client)
     if (client->subdir_inode)
         inode_unref(client->subdir_inode);
 
+    LOCK_DESTROY(&client->scratch_ctx.lock);
+
     GF_FREE(client->auth.data);
     GF_FREE(client->auth.username);
     GF_FREE(client->auth.passwd);