fixup! fixup! gnrc_sixlowpan_frag_sfr: provide CongURE support

RIOT-OS · Oct 25, 2022 · 3e616d3 · 3e616d3
1 parent cbf2b58
commit 3e616d3
Showing 1 changed file with 29 additions and 24 deletions.
diff --git a/sys/net/gnrc/network_layer/sixlowpan/frag/sfr/gnrc_sixlowpan_frag_sfr.c b/sys/net/gnrc/network_layer/sixlowpan/frag/sfr/gnrc_sixlowpan_frag_sfr.c
@@ -1676,30 +1676,35 @@ static void _send_ack(gnrc_netif_t *netif, const uint8_t *dst, uint8_t dst_len,
 
 static void _sched_next_frame(gnrc_sixlowpan_frag_fb_t *fbuf)
 {
-    if (gnrc_sixlowpan_frag_sfr_congure_snd_has_inter_frame_gap()) {
-        int state = irq_disable();  /* make timer check atomic */
-        bool already_set = xtimer_is_set(&_if_gap_timer);
-
-        irq_restore(state);
-        if (!already_set) {
-            uint32_t last_sent_since = (_last_frame_sent - xtimer_now_usec());
-            uint32_t if_gap = gnrc_sixlowpan_frag_sfr_congure_snd_inter_frame_gap(fbuf);
-
-            if (last_sent_since <= if_gap) {
-                uint32_t offset = if_gap - last_sent_since;
-                DEBUG("6lo sfr: arming inter-frame timer in %" PRIu32 " us\n",
-                      last_sent_since);
-                _if_gap_msg.content.ptr = fbuf;
-                xtimer_set_msg(&_if_gap_timer, offset, &_if_gap_msg, _getpid());
-            }
-            else {
-                DEBUG("6lo sfr: send frame immediately\n");
-                gnrc_sixlowpan_frag_sfr_inter_frame_gap(fbuf);
-            }
-        }
-        else {
-            DEBUG("6lo sfr: inter-frame timer was already set\n");
-        }
+    if (!gnrc_sixlowpan_frag_sfr_congure_snd_has_inter_frame_gap()) {
+        return;
+    }
+    int state = irq_disable();  /* make timer check atomic */
+    bool already_set = xtimer_is_set(&_if_gap_timer);
+
+    irq_restore(state);
+    if (already_set) {
+        DEBUG("6lo sfr: inter-frame timer was already set\n");
+        return;
+    }
+    uint32_t last_sent_since = (_last_frame_sent - xtimer_now_usec());
+    uint32_t if_gap = gnrc_sixlowpan_frag_sfr_congure_snd_inter_frame_gap(fbuf);
+
+    if (last_sent_since <= if_gap) {
+        uint32_t offset = if_gap - last_sent_since;
+        DEBUG("6lo sfr: arming inter-frame timer in %" PRIu32 " us\n",
+              last_sent_since);
+        _if_gap_msg.content.ptr = fbuf;
+        xtimer_set_msg(&_if_gap_timer, offset, &_if_gap_msg, _getpid());
+    }
+    else {
+        DEBUG("6lo sfr: send frame immediately\n");
+        /* there is no risk of infinite recursion due to the call of `_sched_next_frame` since
+         * we only get here when (_last_frame_sent - now) > if_gap.
+         * Since gnrc_sixlowpan_frag_sfr_inter_frame_gap updates _last_frame_sent when the list is
+         * empty and only calls _sched_next_frame() when the list is still not empty after that this
+         * can not be the case if we came from there (except for misconfigured if_gap). */
+        gnrc_sixlowpan_frag_sfr_inter_frame_gap(fbuf);
     }
 }