From: Steven Rostedt Date: Tue, 17 Nov 2009 13:43:01 +0000 (-0500) Subject: ring-buffer: Move access to commit_page up into function used X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=5a50e33cc916f6a81cb96f0f24f6a88c9ab78b79;p=deliverable%2Flinux.git 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 --- diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 3ffa502fb243..4b8293fa545e 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 */