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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>
This commit is contained in:
Steven Rostedt 2009-05-06 15:30:07 -04:00 committed by Steven Rostedt
parent 00c81a58c5
commit 6634ff26cc
1 changed files with 49 additions and 40 deletions
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89
kernel/trace/ring_buffer.c
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@ -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)