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>

1 files changed, 49 insertions, 40 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 03ed52b67db3..3ae5ccf2c0fc 100644
--- 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)