io_uring/cmd: return -EOPNOTSUPP if net is disabled

Protect io_uring_cmd_sock() to be called if CONFIG_NET is not set. If
network is not enabled, but io_uring is, then we want to return
-EOPNOTSUPP for any possible socket operation.

This is helpful because io_uring_cmd_sock() can now call functions that
only exits if CONFIG_NET is enabled without having #ifdef CONFIG_NET
inside the function itself.
Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://lore.kernel.org/r/20231016134750.1381153-9-leitao@debian.orgSigned-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/uring_cmd.c

@@ -214,6 +214,7 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
 }
 EXPORT_SYMBOL_GPL(io_uring_cmd_import_fixed);
 
+#if defined(CONFIG_NET)
 int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
 {
 	struct socket *sock = cmd->file->private_data;
@@ -240,3 +241,4 @@ int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
 	}
 }
 EXPORT_SYMBOL_GPL(io_uring_cmd_sock);
+#endif