diff options
| -rw-r--r-- | kernel/trace/ring_buffer.c | 32 |
1 files changed, 8 insertions, 24 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index ab102e6259bc..631541a53baf 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1001,17 +1001,13 @@ static int rb_head_page_replace(struct buffer_page *old, /* * rb_tail_page_update - move the tail page forward - * - * Returns 1 if moved tail page, 0 if someone else did. */ -static int rb_tail_page_update(struct ring_buffer_per_cpu *cpu_buffer, +static void rb_tail_page_update(struct ring_buffer_per_cpu *cpu_buffer, struct buffer_page *tail_page, struct buffer_page *next_page) { - struct buffer_page *old_tail; unsigned long old_entries; unsigned long old_write; - int ret = 0; /* * The tail page now needs to be moved forward. @@ -1061,14 +1057,9 @@ static int rb_tail_page_update(struct ring_buffer_per_cpu *cpu_buffer, */ local_set(&next_page->page->commit, 0); - old_tail = cmpxchg(&cpu_buffer->tail_page, - tail_page, next_page); - - if (old_tail == tail_page) - ret = 1; + /* Again, either we update tail_page or an interrupt does */ + (void)cmpxchg(&cpu_buffer->tail_page, tail_page, next_page); } - - return ret; } static int rb_check_bpage(struct ring_buffer_per_cpu *cpu_buffer, @@ -2150,7 +2141,6 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer *buffer = cpu_buffer->buffer; struct buffer_page *next_page; int ret; - u64 ts; next_page = tail_page; @@ -2224,15 +2214,7 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, } } - ret = rb_tail_page_update(cpu_buffer, tail_page, next_page); - if (ret) { - /* - * Nested commits always have zero deltas, so - * just reread the time stamp - */ - ts = rb_time_stamp(buffer); - next_page->page->time_stamp = ts; - } + rb_tail_page_update(cpu_buffer, tail_page, next_page); out_again: @@ -2422,8 +2404,10 @@ rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) local_set(&cpu_buffer->commit_page->page->commit, rb_page_write(cpu_buffer->commit_page)); rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); - cpu_buffer->write_stamp = - cpu_buffer->commit_page->page->time_stamp; + /* Only update the write stamp if the page has an event */ + if (rb_page_write(cpu_buffer->commit_page)) + cpu_buffer->write_stamp = + cpu_buffer->commit_page->page->time_stamp; /* add barrier to keep gcc from optimizing too much */ barrier(); } |