powerpc/perf/hv-24x7: Break up single_24x7_request

Break up the function single_24x7_request() into smaller functions.
This would later enable us to "prepare" a multi-event request
buffer and then submit a single hcall for several events.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/perf/hv-24x7.c

@@ -1002,6 +1002,44 @@ static void log_24x7_hcall(struct hv_24x7_request_buffer *request_buffer,
 			result_buffer->failing_request_ix);
 }
 
+/*
+ * Start the process for a new H_GET_24x7_DATA hcall.
+ */
+static void init_24x7_request(struct hv_24x7_request_buffer *request_buffer,
+			struct hv_24x7_data_result_buffer *result_buffer)
+{
+
+	memset(request_buffer, 0, 4096);
+	memset(result_buffer, 0, 4096);
+
+	request_buffer->interface_version = HV_24X7_IF_VERSION_CURRENT;
+	/* memset above set request_buffer->num_requests to 0 */
+}
+
+/*
+ * Commit (i.e perform) the H_GET_24x7_DATA hcall using the data collected
+ * by 'init_24x7_request()' and 'add_event_to_24x7_request()'.
+ */
+static int make_24x7_request(struct hv_24x7_request_buffer *request_buffer,
+			struct hv_24x7_data_result_buffer *result_buffer)
+{
+	unsigned long ret;
+
+	/*
+	 * NOTE: Due to variable number of array elements in request and
+	 *	 result buffer(s), sizeof() is not reliable. Use the actual
+	 *	 allocated buffer size, H24x7_DATA_BUFFER_SIZE.
+	 */
+	ret = plpar_hcall_norets(H_GET_24X7_DATA,
+			virt_to_phys(request_buffer), H24x7_DATA_BUFFER_SIZE,
+			virt_to_phys(result_buffer),  H24x7_DATA_BUFFER_SIZE);
+
+	if (ret)
+		log_24x7_hcall(request_buffer, result_buffer, ret);
+
+	return ret;
+}
+
 /*
  * Add the given @event to the next slot in the 24x7 request_buffer.
  *
@@ -1044,7 +1082,6 @@ static int add_event_to_24x7_request(struct perf_event *event,
 static unsigned long single_24x7_request(struct perf_event *event, u64 *count)
 {
 	unsigned long ret;
-
 	struct hv_24x7_request_buffer *request_buffer;
 	struct hv_24x7_data_result_buffer *result_buffer;
 	struct hv_24x7_result *resb;
@@ -1055,31 +1092,22 @@ static unsigned long single_24x7_request(struct perf_event *event, u64 *count)
 	request_buffer = (void *)get_cpu_var(hv_24x7_reqb);
 	result_buffer = (void *)get_cpu_var(hv_24x7_resb);
 
-	memset(request_buffer, 0, 4096);
-	memset(result_buffer, 0, 4096);
-
-	request_buffer->interface_version = HV_24X7_IF_VERSION_CURRENT;
+	init_24x7_request(request_buffer, result_buffer);
 
 	ret = add_event_to_24x7_request(event, request_buffer);
 	if (ret)
 		return ret;
 
-	/*
-	 * NOTE: Due to variable number of array elements in request and
-	 *	 result buffer(s), sizeof() is not reliable. Use the actual
-	 *	 allocated buffer size, H24x7_DATA_BUFFER_SIZE.
-	 */
-	ret = plpar_hcall_norets(H_GET_24X7_DATA,
-			virt_to_phys(request_buffer), H24x7_DATA_BUFFER_SIZE,
-			virt_to_phys(result_buffer),  H24x7_DATA_BUFFER_SIZE);
-
+	ret = make_24x7_request(request_buffer, result_buffer);
 	if (ret) {
 		log_24x7_hcall(request_buffer, result_buffer, ret);
 		goto out;
 	}
 
+	/* process result from hcall */
 	resb = &result_buffer->results[0];
 	*count = be64_to_cpu(resb->elements[0].element_data[0]);
+
 out:
 	return ret;
 }