Commit-ID: 5a50e33cc916f6a81cb96f0f24f6a88c9ab78b79
Gitweb: http://git.kernel.org/tip/5a50e33cc916f6a81cb96f0f24f6a88c9ab78b79
Author: Steven Rostedt <srostedt@xxxxxxxxxx>
AuthorDate: Tue, 17 Nov 2009 08:43:01 -0500
Committer: Steven Rostedt <rostedt@xxxxxxxxxxx>
CommitDate: Tue, 17 Nov 2009 08:43:01 -0500
ring-buffer: Move access to commit_page up into function used
With the change of the way we process commits. Where a commit only happens
at the outer most level, and that we don't need to worry about
a commit ending after the rb_start_commit() has been called, the code
use to grab the commit page before the tail page to prevent a possible
race. But this race no longer exists with the rb_start_commit()
rb_end_commit() interface.
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
kernel/trace/ring_buffer.c | 9 +++------
1 files changed, 3 insertions(+), 6 deletions(-)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 3ffa502..4b8293f 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1785,9 +1785,9 @@ rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer,
static struct ring_buffer_event *
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 *commit_page = cpu_buffer->commit_page;
struct ring_buffer *buffer = cpu_buffer->buffer;
struct buffer_page *next_page;
int ret;
@@ -1890,13 +1890,10 @@ 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 buffer_page *tail_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);
@@ -1907,7 +1904,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
/* 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);
+ tail_page, ts);
/* We reserved something on the buffer */
--
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