[Nexthop] warm-reboot: disable FLOW_CNT_TRAP before warm shutdown

scripts/fast-reboot

@@ -5,6 +5,7 @@ REBOOT_USER="$(logname 2> /dev/null || whoami)"
 REBOOT_TIME=$(date)
 REBOOT_CAUSE_FILE="/host/reboot-cause/reboot-cause.txt"
 WARM_DIR=/host/warmboot
+FLOW_CNT_TRAP_MARKER="${WARM_DIR}/flow_cnt_trap_need_re_enable"
 REDIS_FILE=dump.rdb
 CONFIG_DB_FILE=/etc/sonic/config_db.json
 REBOOT_SCRIPT_NAME=$(basename $0)
@@ -365,6 +366,14 @@ function clear_boot()
     if [[ "$REBOOT_TYPE" = "fast-reboot" ]]; then
         sonic-db-cli STATE_DB HSET "FAST_RESTART_ENABLE_TABLE|system" "enable" "false" &>/dev/null || /bin/true
     fi
+
+    # roll back FLOW_CNT_TRAP=disable if we disabled it but never reached
+    # kexec. Marker presence proves we owned the disable.
+    if [[ -f "$FLOW_CNT_TRAP_MARKER" ]]; then
+        debug "Restoring FLOW_CNT_TRAP=enable after aborted warm-reboot"
+        execute_in_namespaces asic enable_flow_cnt_trap || /bin/true
+        rm -f "$FLOW_CNT_TRAP_MARKER"
+    fi
 }
 
 function init_warm_reboot_states()
@@ -1118,11 +1127,62 @@ function pause_orchagent()
     debug "Orchagent paused successfully"
 }
 
+# When FLOW_CNT_TRAP is enabled, orchagent binds a
+# SAI_COUNTER per HOSTIF trap via SAI_HOSTIF_TRAP_ATTR_COUNTER_ID. After warm
+# boot, APPLY_VIEW replays that attribute and Broadcom SAI fails the lookup:
+#   _brcm_sai_set_hostif_entryctr: field entry stat attach failed with error
+#   Entry not found (BCM_E_NOT_FOUND) -> SAI_STATUS_ITEM_NOT_FOUND
+# syncd then enters shutdown-wait and orchagent crash-loops. Disabling the
+# flex counter pre-shutdown drives CoppOrch::clearHostIfTrapCounterIdList(),
+# which unbinds every counter while the SAI handle is still valid -- no
+# replay is needed on the new boot. The marker file signals
+# finalize-warmboot.sh to re-enable the counter after reconcile.
+function disable_flow_cnt_trap_for_warmboot()
+{
+    local key="FLEX_COUNTER_TABLE|FLOW_CNT_TRAP"
+    local cur
+    cur=$(sonic-db-cli -n "$NETNS" CONFIG_DB HGET "$key" FLEX_COUNTER_STATUS 2>/dev/null)
+    if [[ "$cur" != "enable" ]]; then
+        debug "FLOW_CNT_TRAP not enabled (status='${cur}'), skipping pre-warmboot disable"
+        # Drop any marker left by a prior aborted warm-reboot so it doesn't
+        # falsely re-enable a counter the user has since disabled.
+        rm -f "$FLOW_CNT_TRAP_MARKER"
+        return
+    fi
+    debug "FLOW_CNT_TRAP=enable: disabling pre-warmboot"
+    mkdir -p "${WARM_DIR}"
+    touch "$FLOW_CNT_TRAP_MARKER"
+    sonic-db-cli -n "$NETNS" CONFIG_DB HSET "$key" FLEX_COUNTER_STATUS disable > /dev/null
+    # Poll COUNTERS_TRAP_NAME_MAP until CoppOrch drains it — that proves every
+    # SAI_HOSTIF_TRAP_ATTR_COUNTER_ID unbind has completed in orchagent's thread.
+    local deadline=$((SECONDS + 10))
+    local n
+    while (( SECONDS < deadline )); do
+        n=$(sonic-db-cli -n "$NETNS" COUNTERS_DB HLEN COUNTERS_TRAP_NAME_MAP 2>/dev/null || echo 0)
+        [[ "$n" == "0" ]] && break
+    done
+    if [[ "${n:-0}" != "0" ]]; then
+        debug "WARN: COUNTERS_TRAP_NAME_MAP still has ${n} entries after 10s; proceeding"
+    fi
+}
+
+# Re-enable FLOW_CNT_TRAP in CONFIG_DB. Used by clear_boot to roll back the
+# disable_flow_cnt_trap_for_warmboot CONFIG_DB write when warm-reboot aborts
+# before kexec.
+function enable_flow_cnt_trap()
+{
+    sonic-db-cli -n "$NETNS" CONFIG_DB HSET "FLEX_COUNTER_TABLE|FLOW_CNT_TRAP" FLEX_COUNTER_STATUS enable > /dev/null
+}
+
 # After orchagent pause, there's no rollback if anything goes wrong on Multi-ASIC devices, force execution
 if [[ $NUM_ASIC -gt 1 ]]; then
     FORCE=yes
 fi
 
+if [[ "$REBOOT_TYPE" = "warm-reboot" ]]; then
+    execute_in_namespaces asic disable_flow_cnt_trap_for_warmboot
+fi
+
 if [[ "$REBOOT_TYPE" = "warm-reboot" || "$REBOOT_TYPE" = "fastfast-reboot" || "$REBOOT_TYPE" = "express-reboot" || "$REBOOT_TYPE" = "fast-reboot" ]]; then
     execute_in_namespaces asic pause_orchagent
 fi