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 03ed52b67db308c7f05c7e8354551f63a97c8765..3ae5ccf2c0fcd0704948dcf92859b6129e47925f 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1154,51 +1154,18 @@ static unsigned rb_calculate_event_length(unsigned length)
        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 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
        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)