ggml : Fixed race-condition that leads to crashes when using ggml-rpc

Author: gkpln3

CODEOWNERS

@@ -9,3 +9,5 @@
 /ggml/src/ggml-cuda/mmvq.* @JohannesGaessler
 /ggml/src/ggml-opt.cpp @JohannesGaessler
 /ggml/src/gguf.cpp @JohannesGaessler
+/ggml/src/ggml-rpc/* @gkpln3
+/tools/rpc/rpc-server.cpp @gkpln3

ggml/src/ggml-rpc/ggml-rpc.cpp

@@ -386,6 +386,8 @@ static bool parse_endpoint(const std::string & endpoint, std::string & host, int
 // RPC request : | rpc_cmd (1 byte) | request_size (8 bytes) | request_data (request_size bytes) |
 // No response
 static bool send_rpc_cmd(const std::shared_ptr<socket_t> & sock, enum rpc_cmd cmd, const void * input, size_t input_size) {
+    static std::mutex send_rpc_cmd_mutex;
+    std::lock_guard<std::mutex> lock(send_rpc_cmd_mutex);
     uint8_t cmd_byte = cmd;
     if (!send_data(sock->fd, &cmd_byte, sizeof(cmd_byte))) {
         return false;