Results 3 issues of hiiizxf

When I run doc/code/tty/main.c, the process was terminated due to a segment fault. In doc/code/tty/main.c, the function "uv_write" is called twice, and req with the same address is used. And...

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good first issue

### Describe problem solved by the proposed feature _serial_fifo_rx with RT_SERIAL_RX_BLOCKING in serial.c is limited by the buffer size 1.when needed size is large than ringbuffer size, _serial_fifo_rx will do...

### RT-Thread Version head ### Hardware Type/Architectures stm32f2 ### Develop Toolchain Other ### Describe the bug erase() { ... while (erased_size < size) ... } is incorrect. For example: offset...