oprofile: adding cpu_buffer_write_commit()

This is in preparation for changes in the cpu buffer implementation.

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

1 files changed, 17 insertions, 0 deletions

diff --git a/drivers/oprofile/cpu_buffer.h b/drivers/oprofile/cpu_buffer.h
index 08706991fdd2..e6089768ae66 100644
--- a/drivers/oprofile/cpu_buffer.h
+++ b/drivers/oprofile/cpu_buffer.h
@@ -59,6 +59,23 @@ struct op_sample *cpu_buffer_write_entry(struct oprofile_cpu_buffer *cpu_buf)
 }
 
 static inline
+void cpu_buffer_write_commit(struct oprofile_cpu_buffer *b)
+{
+        unsigned long new_head = b->head_pos + 1;
+
+        /*
+         * Ensure anything written to the slot before we increment is
+         * visible
+         */
+        wmb();
+
+        if (new_head < b->buffer_size)
+                b->head_pos = new_head;
+        else
+                b->head_pos = 0;
+}
+
+static inline
 struct op_sample *cpu_buffer_read_entry(struct oprofile_cpu_buffer *cpu_buf)
 {
         return &cpu_buf->buffer[cpu_buf->tail_pos];