Redis [BUG] Potential data race on server.loading flag

Describe the bug

We are developing a static data race detection tool and detected a potential data race on the server.loading flag in redis version 6.0.7

To reproduce

If SIGINT is sent while the main thread is inside of loadDataFromDisk, there is a potential data race on the server.loading flag.

The main thread sets the flag while the signal handler may read the flag in parallel.

==== Found a race between: 
line 1996 in rdb.c AND line 4852 in server.c
Shared variable:
 at line 72 of server.c
 72|struct redisServer server; /* Server global state */
Thread 1:
 1994|void startLoading(size_t size, int rdbflags) {
 1995|    /* Load the DB */
>1996|    server.loading = 1;
 1997|    server.loading_start_time = time(NULL);
 1998|    server.loading_loaded_bytes = 0;
>>>Stacktrace:
>>>main
>>>  loadDataFromDisk [server.c:5272]
>>>    loadAppendOnlyFile [server.c:4967]
>>>      startLoadingFile [aof.c:740]
>>>        startLoading [rdb.c:2020]
Thread 2:
 4850|     rdbRemoveTempFile(getpid());
 4851|     exit(1); /* Exit with an error since this was not a clean shutdown. */
>4852| } else if (server.loading) {
 4853|     serverLogFromHandler(LL_WARNING, "Received shutdown signal during loading, exiting now.");
 4854|     exit(0);

>>>Stacktrace:
>>>sigaction [server.c:4869]
>>>  sigShutdownHandler [server.c:4869]

Expected behavior

Should the read/write to server.loading be made atomic?