fsm: allow graceful exit on FSM termination
The function _osmo_fsm_inst_term() terminates all child FSMs befor
it calls fi->fsm_cleanup(). This prevents the cleanup callback to
perform last actions on the child FSMs (e.g.
osmo_fsm_inst_unlink_parent()).
- Since moving the cleanup callack to the beginning of the function
would alter the termination behavior and possibly cause malfunction
in already existing implementation that use OSMO fsm, a new
optional callback that is called immediately at the beginning of
the terminatopn process is added.
Change-Id: I0fdda9fe994753f975a658c0f3fb3615949cc8bb
Closes: OS#2915
diff --git a/TODO-RELEASE b/TODO-RELEASE
index 782ba19..928b18d 100644
--- a/TODO-RELEASE
+++ b/TODO-RELEASE
@@ -10,3 +10,4 @@
core msgb_queue_free() add inline func to msgb.h
coding gsm0503_rach_ext-encode() add func to gsm0503_coding.h
codec ecu.c / ecu.h implement ECU for FR (Error Concealment Unit)
+fsm fsmc / fsm.h added callback for graceful exit => ABI changed
\ No newline at end of file
diff --git a/include/osmocom/core/fsm.h b/include/osmocom/core/fsm.h
index bbfe312..2c2a996 100644
--- a/include/osmocom/core/fsm.h
+++ b/include/osmocom/core/fsm.h
@@ -78,6 +78,8 @@
int log_subsys;
/*! human-readable names of events */
const struct value_string *event_names;
+ /*! graceful exit function, called at the beginning of termination */
+ void (*pre_term)(struct osmo_fsm_inst *fi, enum osmo_fsm_term_cause cause);
};
/*! a single instanceof an osmocom finite state machine */
diff --git a/src/fsm.c b/src/fsm.c
index a127362..176aa8a 100644
--- a/src/fsm.c
+++ b/src/fsm.c
@@ -298,7 +298,11 @@
/*! unlink child FSM from its parent FSM.
* \param[in] fi Descriptor of the child FSM to unlink.
- * \param[in] ctx New talloc context */
+ * \param[in] ctx New talloc context
+ *
+ * Never call this function from the cleanup callback, because at that time
+ * the child FSMs will already be terminated. If unlinking should be performed
+ * on FSM termination, use the grace callback instead. */
void osmo_fsm_inst_unlink_parent(struct osmo_fsm_inst *fi, void *ctx)
{
if (fi->proc.parent) {
@@ -312,7 +316,10 @@
/*! change parent instance of an FSM.
* \param[in] fi Descriptor of the to-be-allocated FSM.
* \param[in] new_parent New parent FSM instance.
- * \param[in] new_parent_term_event Event to be sent to parent when terminating. */
+ * \param[in] new_parent_term_event Event to be sent to parent when terminating.
+ *
+ * Never call this function from the cleanup callback!
+ * (see also osmo_fsm_inst_unlink_parent()).*/
void osmo_fsm_inst_change_parent(struct osmo_fsm_inst *fi,
struct osmo_fsm_inst *new_parent,
uint32_t new_parent_term_event)
@@ -528,6 +535,10 @@
LOGPFSMSRC(fi, file, line, "Terminating (cause = %s)\n",
osmo_fsm_term_cause_name(cause));
+ /* graceful exit (optional) */
+ if (fi->fsm->pre_term)
+ fi->fsm->pre_term(fi, cause);
+
_osmo_fsm_inst_term_children(fi, OSMO_FSM_TERM_PARENT, NULL,
file, line);