[GitHub] [incubator-nuttx] gustavonihei commented on pull request #6322: ESP32/ESP32-C3: Fix leak of semaphores created by Wi-Fi kernel thread

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gustavonihei commented on PR #6322:
URL: https://github.com/apache/incubator-nuttx/pull/6322#issuecomment-1136361775

   The Wi-Fi library creates a new semaphore for every thread that performs connection operations, so we cannot have a global pointer.
   Since these semaphores are thread-local, this motivated the initial implementation based on `pthread_key_t`, so that the semaphores were being stored in Thread Local Storage, and then could be destroyed on thread termination. The solution here was based on the one implemented for ESP-IDF, which works as expected.
   
   But on NuttX it resulted in the semaphores not being destroyed. I'll try to explain why.
   The Wi-Fi library operates in a dedicated Kernel Thread, named `wifi`. But the `pthread_key_t` and the destructor for the semaphores were allocated to the Thread Local Storage of the `init` thread.
   Every network-related request from the application will be handled by the `wifi` kernel thread and its child pthreads. The issue is that those child pthreads do not belong to the same Task Group from the `init` thread, which is the one whose TLS area contains the semaphore destructor.
   
   So the catch here is that NuttX provides this process-like abstraction which segregates pthreads created from different tasks. So a pthread created from **Task B** won't be able to share keys with another pthread from **Task A**.


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