ring-buffer: make moving the tail page a separate function
Ingo Molnar thought the code would be cleaner if we used a function call
instead of a goto for moving the tail page. After implementing this,
it seems that gcc still inlines the result and the output is pretty much
the same. Since this is considered a cleaner approach, might as well
implement it.
[ Impact: code clean up ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 03ed52b..3ae5ccf 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1154,51 +1154,18 @@
return length;
}
+
static struct ring_buffer_event *
-__rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
- unsigned type, unsigned long length, u64 *ts)
+rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer,
+ unsigned long length, unsigned long tail,
+ struct buffer_page *commit_page,
+ struct buffer_page *tail_page, u64 *ts)
{
- struct buffer_page *tail_page, *head_page, *reader_page, *commit_page;
- struct buffer_page *next_page;
- unsigned long tail, write;
+ struct buffer_page *next_page, *head_page, *reader_page;
struct ring_buffer *buffer = cpu_buffer->buffer;
struct ring_buffer_event *event;
- unsigned long flags;
bool lock_taken = false;
-
- commit_page = cpu_buffer->commit_page;
- /* we just need to protect against interrupts */
- barrier();
- tail_page = cpu_buffer->tail_page;
- write = local_add_return(length, &tail_page->write);
- tail = write - length;
-
- /* See if we shot pass the end of this buffer page */
- if (write > BUF_PAGE_SIZE)
- goto next_page;
-
- /* We reserved something on the buffer */
-
- if (RB_WARN_ON(cpu_buffer, write > BUF_PAGE_SIZE))
- return NULL;
-
- event = __rb_page_index(tail_page, tail);
- rb_update_event(event, type, length);
-
- /* The passed in type is zero for DATA */
- if (likely(!type))
- local_inc(&tail_page->entries);
-
- /*
- * If this is a commit and the tail is zero, then update
- * this page's time stamp.
- */
- if (!tail && rb_is_commit(cpu_buffer, event))
- cpu_buffer->commit_page->page->time_stamp = *ts;
-
- return event;
-
- next_page:
+ unsigned long flags;
next_page = tail_page;
@@ -1318,6 +1285,48 @@
return NULL;
}
+static struct ring_buffer_event *
+__rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
+ unsigned type, unsigned long length, u64 *ts)
+{
+ struct buffer_page *tail_page, *commit_page;
+ struct ring_buffer_event *event;
+ unsigned long tail, write;
+
+ commit_page = cpu_buffer->commit_page;
+ /* we just need to protect against interrupts */
+ barrier();
+ tail_page = cpu_buffer->tail_page;
+ write = local_add_return(length, &tail_page->write);
+ tail = write - length;
+
+ /* See if we shot pass the end of this buffer page */
+ if (write > BUF_PAGE_SIZE)
+ return rb_move_tail(cpu_buffer, length, tail,
+ commit_page, tail_page, ts);
+
+ /* We reserved something on the buffer */
+
+ if (RB_WARN_ON(cpu_buffer, write > BUF_PAGE_SIZE))
+ return NULL;
+
+ event = __rb_page_index(tail_page, tail);
+ rb_update_event(event, type, length);
+
+ /* The passed in type is zero for DATA */
+ if (likely(!type))
+ local_inc(&tail_page->entries);
+
+ /*
+ * If this is a commit and the tail is zero, then update
+ * this page's time stamp.
+ */
+ if (!tail && rb_is_commit(cpu_buffer, event))
+ cpu_buffer->commit_page->page->time_stamp = *ts;
+
+ return event;
+}
+
static int
rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer,
u64 *ts, u64 *delta)