Commit 6634ff26 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt
Browse files

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: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 00c81a58

kernel/trace/ring_buffer.c

+49 −40
Original line number Diff line number Diff line
@@ -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)

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