Revert "trx_if: Allow calling trx_if_flush/close from within TRXC callback"

This reverts commit 4444262a6ab1e1e231ea81c4ec990f1a1f571a1f.
This commit introduced several side effects:
- tcm is left out of the l1h->trx_ctrl_list and hence won't be ever
  retransmitted.
- Since tcm is removed before rsp callback, the llist may become empty
  and if somehwere in the rsp callback a new message is enqueud it will
  be sent immediatelly, and will be retransmitted again when
trx_ctrl_read_cb() calls trx_ctrl_send() at the end.

Change-Id: Ideb2d08ac8a2902bceeabfb055c59c9a13dbe3c0
Related: OS#6020
---
M src/osmo-bts-trx/trx_if.c
1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/src/osmo-bts-trx/trx_if.c b/src/osmo-bts-trx/trx_if.c
index fef8c22..3f9fc04 100644
--- a/src/osmo-bts-trx/trx_if.c
+++ b/src/osmo-bts-trx/trx_if.c
@@ -721,13 +721,6 @@
 
 	rsp.cb = tcm->cb;
 
-	/* Remove command from list, save it to last_acked and remove previous
-	 * last_acked. Do it before calling callback to avoid user freeing tcm
-	 * pointer if flushing/closing the iface. */
-	llist_del(&tcm->list);
-	talloc_free(l1h->last_acked);
-	l1h->last_acked = tcm;
-
 	/* check for response code */
 	rc = trx_ctrl_rx_rsp(l1h, &rsp, tcm);
 	if (rc == -EINVAL)
@@ -735,11 +728,15 @@
 
 	/* re-schedule last cmd in rc seconds time */
 	if (rc > 0) {
-		if (!llist_empty(&l1h->trx_ctrl_list))
-			osmo_timer_schedule(&l1h->trx_ctrl_timer, rc, 0);
+		osmo_timer_schedule(&l1h->trx_ctrl_timer, rc, 0);
 		return 0;
 	}
 
+	/* remove command from list, save it to last_acked and removed previous last_acked */
+	llist_del(&tcm->list);
+	talloc_free(l1h->last_acked);
+	l1h->last_acked = tcm;
+
 	trx_ctrl_send(l1h);
 
 	return 0;

