TT#183850 tm: try not to crash on unref

Change-Id: Ia0275a6a624ae748aece92ef538891b17c3e767f

debian/patches/series

@@ -59,6 +59,7 @@ sipwise/dialog-support-profile_get_size-for-all-profiles.patch
 sipwise/pv_headers-rework-pvh_remove_header_param.patch
 ### active development
 sipwise/presence-be-more-resilient-doing-clean-up.patch
+sipwise/tm-check-again-T-just-in-case-before-UNREF.patch
 #
 ### Don't just put stuff in any order
 ### use gbp pq import/export tooling to help maintain patches

debian/patches/sipwise/tm-check-again-T-just-in-case-before-UNREF.patch

@@ -0,0 +1,21 @@
+From: Victor Seva <vseva@sipwise.com>
+Date: Mon, 4 Jul 2022 15:49:20 +0200
+Subject: tm: check T just in case before UNREF
+
+---
+ src/modules/tm/t_funcs.h | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/modules/tm/t_funcs.h b/src/modules/tm/t_funcs.h
+index 6830b13..dbbdc19 100644
+--- a/src/modules/tm/t_funcs.h
++++ b/src/modules/tm/t_funcs.h
+@@ -110,7 +110,7 @@ int send_pr_buffer( struct retr_buf *rb, void *buf, int len);
+ 
+ #define UNREF_NOSTATS(_T_cell) \
+ 	do{\
+-		if (atomic_dec_and_test(&(_T_cell)->ref_count)){ \
++		if (_T_cell && atomic_dec_and_test(&(_T_cell)->ref_count)){ \
+ 			unlink_timers((_T_cell)); \
+ 			free_cell((_T_cell)); \
+ 		}\