From eeec8a4f815ddd774108760a11bea8d76fa1d9fa Mon Sep 17 00:00:00 2001
From: Florian Pose <fp@igh.de>
Date: Thu, 16 Jul 2026 13:52:53 +0200
Subject: [PATCH] More general approach: Check for maximum datagram size in
 pre-alloc.

---
 master/datagram.c     | 12 ++++++++++--
 master/fmmu_config.c  | 12 ++----------
 master/fmmu_config.h  |  2 +-
 master/slave_config.c |  7 +------
 4 files changed, 14 insertions(+), 19 deletions(-)

diff --git a/master/datagram.c b/master/datagram.c
index c0f3360a..f35323a8 100644
--- a/master/datagram.c
+++ b/master/datagram.c
@@ -1,6 +1,6 @@
 /*****************************************************************************
  *
- *  Copyright (C) 2006-2008  Florian Pose, Ingenieurgemeinschaft IgH
+ *  Copyright (C) 2006-2026  Florian Pose, Ingenieurgemeinschaft IgH
  *
  *  This file is part of the IgH EtherCAT Master.
  *
@@ -145,8 +145,16 @@ int ec_datagram_prealloc(
         )
 {
     if (datagram->data_origin == EC_ORIG_EXTERNAL
-            || size <= datagram->mem_size)
+            || size <= datagram->mem_size) {
         return 0;
+    }
+
+    if (size > EC_MAX_DATA_SIZE) {
+        EC_ERR("%s(datagram = %p, size = %zu): Exceeding the"
+                " maximum datagram size of %u bytes.\n",
+                __func__, datagram, size, EC_MAX_DATA_SIZE);
+        return -EOVERFLOW;
+    }
 
     if (datagram->data) {
         kfree(datagram->data);
diff --git a/master/fmmu_config.c b/master/fmmu_config.c
index 7d3f452a..52985952 100644
--- a/master/fmmu_config.c
+++ b/master/fmmu_config.c
@@ -1,6 +1,6 @@
 /*****************************************************************************
  *
- *  Copyright (C) 2006-2008  Florian Pose, Ingenieurgemeinschaft IgH
+ *  Copyright (C) 2006-2026  Florian Pose, Ingenieurgemeinschaft IgH
  *
  *  This file is part of the IgH EtherCAT Master.
  *
@@ -39,7 +39,7 @@
  * process data size for the mapped PDOs of the given direction to the domain
  * data size.
  */
-int ec_fmmu_config_init(
+void ec_fmmu_config_init(
         ec_fmmu_config_t *fmmu, /**< EtherCAT FMMU configuration. */
         ec_slave_config_t *sc, /**< EtherCAT slave configuration. */
         ec_domain_t *domain, /**< EtherCAT domain. */
@@ -56,15 +56,7 @@ int ec_fmmu_config_init(
     fmmu->data_size = ec_pdo_list_total_size(
             &sc->sync_configs[sync_index].pdos);
 
-    if (fmmu->data_size > EC_MAX_DATA_SIZE) {
-        EC_CONFIG_ERR(fmmu->sc, "FMMU with data size %3u bytes would exceed"
-                " maximum datagram size (%u bytes).\n",
-                fmmu->data_size, EC_MAX_DATA_SIZE);
-        return -ENOMEM;
-    }
-
     ec_domain_add_fmmu_config(domain, fmmu);
-    return 0;
 }
 
 /****************************************************************************/
diff --git a/master/fmmu_config.h b/master/fmmu_config.h
index bd74e98a..a2323038 100644
--- a/master/fmmu_config.h
+++ b/master/fmmu_config.h
@@ -47,7 +47,7 @@ typedef struct {
 
 /****************************************************************************/
 
-int ec_fmmu_config_init(ec_fmmu_config_t *, ec_slave_config_t *,
+void ec_fmmu_config_init(ec_fmmu_config_t *, ec_slave_config_t *,
         ec_domain_t *, uint8_t, ec_direction_t);
 
 void ec_fmmu_config_page(const ec_fmmu_config_t *, const ec_sync_t *,
diff --git a/master/slave_config.c b/master/slave_config.c
index 9f6a0dcf..311e6147 100644
--- a/master/slave_config.c
+++ b/master/slave_config.c
@@ -222,7 +222,6 @@ int ec_slave_config_prepare_fmmu(
 {
     unsigned int i;
     ec_fmmu_config_t *fmmu;
-    int ret = 0;
 
     // FMMU configuration already prepared?
     for (i = 0; i < sc->used_fmmus; i++) {
@@ -239,13 +238,9 @@ int ec_slave_config_prepare_fmmu(
     fmmu = &sc->fmmu_configs[sc->used_fmmus++];
 
     down(&sc->master->master_sem);
-    ret = ec_fmmu_config_init(fmmu, sc, domain, sync_index, dir);
+    ec_fmmu_config_init(fmmu, sc, domain, sync_index, dir);
     up(&sc->master->master_sem);
 
-    if (ret < 0) {
-        return ret;
-    }
-
     return fmmu->logical_start_address;
 }