Don't his the lwip_callback data structure

No need to add obscure __align__ if we don't pretend it's an array of bytes

Author: earlephilhower

cores/rp2040/lwip_wrap.cpp

@@ -825,13 +825,12 @@ extern "C" {
         return __real_ethernet_input(p, netif);
     }
 
-    void lwip_callback(void (*cb)(void *), void *cbData, void *buffer) {
+    void lwip_callback(void (*cb)(void *), void *cbData, __callback_req *buffer) {
 #ifdef __FREERTOS
         if (buffer) {
-            __callback_req *req = (__callback_req *)buffer;
-            req->cb = cb;
-            req->cbData = cbData;
-            __lwip(__callback, req, true);
+            buffer->cb = cb;
+            buffer->cbData = cbData;
+            __lwip(__callback, buffer, true);
             return;
         } else if (!__isLWIPThread()) {
             __callback_req req = { cb, cbData };

cores/rp2040/lwip_wrap.h

@@ -569,14 +569,12 @@ typedef struct {
 } __ethernet_input_req;
 
 // Run a callback in the LWIP thread (i.e. for Ethernet device polling and packet reception)
-// When in an interrupt, need to pass in a heap-allocated buffer (i.e. class variable) of
-// size LWIP_CALLBACK_BUFFER_SIZE that will be used to store the request.
-extern void lwip_callback(void (*cb)(void *), void *cbData, void *buffer = nullptr);
+// When in an interrupt, need to pass in a heap-allocated buffer
 typedef struct {
     void (*cb)(void *);
     void *cbData;
 } __callback_req;
-#define LWIP_CALLBACK_BUFFER_SIZE sizeof(__callback_req)
+extern void lwip_callback(void (*cb)(void *), void *cbData, __callback_req *buffer = nullptr);
 
 #ifdef __cplusplus
 };

libraries/lwIP_Ethernet/src/LwipIntfDev.h

@@ -194,8 +194,8 @@ class LwipIntfDev: public LwipIntf, public RawDev {
     err_t handlePackets();
 #ifdef __FREERTOS
     SemaphoreHandle_t _hwMutex;
+    __callback_req _irqBuffer;
 #endif
-    uint8_t _irqBuffer[LWIP_CALLBACK_BUFFER_SIZE] __attribute__ ((aligned (4)));;
 protected:
     // members
     SPIClass& _spiUnit;
@@ -490,7 +490,7 @@ template<class RawDev>
 void LwipIntfDev<RawDev>::_irq(void *param) {
     LwipIntfDev *d = static_cast<LwipIntfDev*>(param);
     ethernet_arch_lwip_gpio_mask(); // Disable other IRQs until we're done processing this one
-    lwip_callback(_lwipCallback, param, (void *)d->_irqBuffer);
+    lwip_callback(_lwipCallback, param, &d->_irqBuffer);
     //ethernet_arch_lwip_begin();
     //    d->handlePackets();
     //    sys_check_timeouts();