dlm: add __CHECKER__ for false positives

This patch will adds #ifndef __CHECKER__ for false positives warnings
about an imbalance lock/unlock srcu handling. Which are shown by running
sparse checks:

fs/dlm/midcomms.c:1065:20: warning: context imbalance in 'dlm_midcomms_get_mhandle' - wrong count at exit

Using __CHECKER__ will tell sparse to ignore these sections.

Those imbalances are false positive because from upper layer it is
always required to call a function in sequence, e.g. if
dlm_midcomms_get_mhandle() is successful there must be a
dlm_midcomms_commit_mhandle() call afterwards.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

fs/dlm/lowcomms.c

@@ -1303,6 +1303,10 @@ static struct dlm_msg *dlm_lowcomms_new_msg_con(struct connection *con, int len,
 	return msg;
 }
 
+/* avoid false positive for nodes_srcu, unlock happens in
+ * dlm_lowcomms_commit_msg which is a must call if success
+ */
+#ifndef __CHECKER__
 struct dlm_msg *dlm_lowcomms_new_msg(int nodeid, int len, gfp_t allocation,
 				     char **ppc, void (*cb)(void *data),
 				     void *data)
@@ -1336,6 +1340,7 @@ struct dlm_msg *dlm_lowcomms_new_msg(int nodeid, int len, gfp_t allocation,
 	msg->idx = idx;
 	return msg;
 }
+#endif
 
 static void _dlm_lowcomms_commit_msg(struct dlm_msg *msg)
 {
@@ -1362,11 +1367,16 @@ out:
 	return;
 }
 
+/* avoid false positive for nodes_srcu, lock was happen in
+ * dlm_lowcomms_new_msg
+ */
+#ifndef __CHECKER__
 void dlm_lowcomms_commit_msg(struct dlm_msg *msg)
 {
 	_dlm_lowcomms_commit_msg(msg);
 	srcu_read_unlock(&connections_srcu, msg->idx);
 }
+#endif
 
 void dlm_lowcomms_put_msg(struct dlm_msg *msg)
 {

fs/dlm/midcomms.c

@@ -1062,6 +1062,10 @@ static struct dlm_msg *dlm_midcomms_get_msg_3_2(struct dlm_mhandle *mh, int node
 	return msg;
 }
 
+/* avoid false positive for nodes_srcu, unlock happens in
+ * dlm_midcomms_commit_mhandle which is a must call if success
+ */
+#ifndef __CHECKER__
 struct dlm_mhandle *dlm_midcomms_get_mhandle(int nodeid, int len,
 					     gfp_t allocation, char **ppc)
 {
@@ -1127,6 +1131,7 @@ err:
 	srcu_read_unlock(&nodes_srcu, idx);
 	return NULL;
 }
+#endif
 
 static void dlm_midcomms_commit_msg_3_2(struct dlm_mhandle *mh)
 {
@@ -1136,6 +1141,10 @@ static void dlm_midcomms_commit_msg_3_2(struct dlm_mhandle *mh)
 	dlm_lowcomms_commit_msg(mh->msg);
 }
 
+/* avoid false positive for nodes_srcu, lock was happen in
+ * dlm_midcomms_get_mhandle
+ */
+#ifndef __CHECKER__
 void dlm_midcomms_commit_mhandle(struct dlm_mhandle *mh)
 {
 	switch (mh->node->version) {
@@ -1157,6 +1166,7 @@ void dlm_midcomms_commit_mhandle(struct dlm_mhandle *mh)
 		break;
 	}
 }
+#endif
 
 int dlm_midcomms_start(void)
 {