oprofile: add op_cpu_buffer_add_data()

This function can be used to attach data to a sample. It returns the
remaining free buffer size that has been reserved with
op_cpu_buffer_write_reserve().

Signed-off-by: Robert Richter <robert.richter@amd.com>

drivers/oprofile/cpu_buffer.c

@@ -258,7 +258,7 @@ op_add_code(struct oprofile_cpu_buffer *cpu_buf, unsigned long backtrace,
 	sample->event = flags;
 
 	if (size)
-		sample->data[0] = (unsigned long)task;
+		op_cpu_buffer_add_data(&entry, (unsigned long)task);
 
 	op_cpu_buffer_write_commit(&entry);
 

drivers/oprofile/cpu_buffer.h

@@ -78,6 +78,18 @@ int op_cpu_buffer_write_commit(struct op_entry *entry);
 struct op_sample *op_cpu_buffer_read_entry(struct op_entry *entry, int cpu);
 unsigned long op_cpu_buffer_entries(int cpu);
 
+/* returns the remaining free size of data in the entry */
+static inline
+int op_cpu_buffer_add_data(struct op_entry *entry, unsigned long val)
+{
+	if (!entry->size)
+		return 0;
+	*entry->data = val;
+	entry->size--;
+	entry->data++;
+	return entry->size;
+}
+
 /* extra data flags */
 #define KERNEL_CTX_SWITCH	(1UL << 0)
 #define IS_KERNEL		(1UL << 1)