fix(freertos): Fixed SMP race condition in stream_buffers.c

This commit fixes a race condition in dual-core SMP mode where in the
xStreamBufferReceive() makes the xTaskWaitingToReceive NULL but it may
have already been evaluated to not be NULL by xStreamBufferSend()
running on another core and eventually leading to a crash in tasks.c.

components/freertos/FreeRTOS-Kernel/idf_changes.md

@@ -123,6 +123,8 @@ The following functions were modified to accommodate SMP behavior:
   - In SMP, the function now disables interrupts to ensure that the calling task does not switch cores while checking its own copy of `uxSchedulerSuspended`.
 - `prvAddCurrentTaskToDelayedList()`
   - Added extra check to see if current blocking task has already been deleted by the other core.
+- `xStreamBufferReceive()`
+  - Added a critical section for setting `xTaskWaitingToReceive` to `NULL` so that the write is SMP safe.
 
 ### Critical Section Changes
 

components/freertos/FreeRTOS-Kernel/stream_buffer.c

@@ -6,7 +6,7 @@
  *
  * SPDX-License-Identifier: MIT
  *
- * SPDX-FileContributor: 2023 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileContributor: 2023-2024 Espressif Systems (Shanghai) CO LTD
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy of
  * this software and associated documentation files (the "Software"), to deal in
@@ -976,7 +976,19 @@ size_t xStreamBufferReceive( StreamBufferHandle_t xStreamBuffer,
             /* Wait for data to be available. */
             traceBLOCKING_ON_STREAM_BUFFER_RECEIVE( xStreamBuffer );
             ( void ) xTaskNotifyWait( ( uint32_t ) 0, ( uint32_t ) 0, NULL, xTicksToWait );
-            pxStreamBuffer->xTaskWaitingToReceive = NULL;
+
+            /* In SMP mode, the task may have been woken and scheduled on
+             * another core. Hence, we must clear the xTaskWaitingToReceive
+             * handle in a critical section. */
+            #if ( configNUMBER_OF_CORES > 1 )
+                taskENTER_CRITICAL( &( pxStreamBuffer->xStreamBufferLock ) );
+            #endif /* configNUMBER_OF_CORES > 1 */
+            {
+                pxStreamBuffer->xTaskWaitingToReceive = NULL;
+            }
+            #if ( configNUMBER_OF_CORES > 1 )
+                taskEXIT_CRITICAL( &( pxStreamBuffer->xStreamBufferLock ) );
+            #endif /* configNUMBER_OF_CORES > 1 */
 
             /* Recheck the data available after blocking. */
             xBytesAvailable = prvBytesInBuffer( pxStreamBuffer );