diff options
| -rw-r--r-- | kernel/trace/ring_buffer.c | 156 |
1 files changed, 50 insertions, 106 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 1cce0fb..fc347f8 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2141,8 +2141,6 @@ rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, local_sub(length, &tail_page->write); } -static inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer); - /* * This is the slow path, force gcc not to inline it. */ @@ -2157,16 +2155,6 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, int ret; u64 ts; - /* - * If the event had a timestamp attached to it, remove it. - * The first event on a page (nested or not) always uses - * the full timestamp of the new page. - */ - if (info->add_timestamp) { - info->add_timestamp = 0; - info->length -= RB_LEN_TIME_EXTEND; - } - next_page = tail_page; rb_inc_page(cpu_buffer, &next_page); @@ -2253,11 +2241,6 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, rb_reset_tail(cpu_buffer, tail, info); - /* Commit what we have for now to update timestamps */ - rb_end_commit(cpu_buffer); - /* rb_end_commit() decs committing */ - local_inc(&cpu_buffer->committing); - /* fail and let the caller try again */ return ERR_PTR(-EAGAIN); @@ -2287,6 +2270,9 @@ rb_add_time_stamp(struct ring_buffer_event *event, u64 delta) return skip_time_extend(event); } +static inline int rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer, + struct ring_buffer_event *event); + /** * rb_update_event - update event type and data * @event: the event to update @@ -2298,7 +2284,7 @@ rb_add_time_stamp(struct ring_buffer_event *event, u64 delta) * and with this, we can determine what to place into the * data field. */ -static void __always_inline +static void rb_update_event(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event, struct rb_event_info *info) @@ -2306,6 +2292,10 @@ rb_update_event(struct ring_buffer_per_cpu *cpu_buffer, unsigned length = info->length; u64 delta = info->delta; + /* Only a commit updates the timestamp */ + if (unlikely(!rb_event_is_commit(cpu_buffer, event))) + delta = 0; + /* * If we need to add a timestamp, then we * add it to the start of the resevered space. @@ -2685,13 +2675,8 @@ EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); static noinline void rb_handle_timestamp(struct ring_buffer_per_cpu *cpu_buffer, - struct ring_buffer_event *event, struct rb_event_info *info) { - struct ring_buffer_event *padding; - int length; - int size; - WARN_ONCE(info->delta > (1ULL << 59), KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s", (unsigned long long)info->delta, @@ -2701,61 +2686,7 @@ rb_handle_timestamp(struct ring_buffer_per_cpu *cpu_buffer, "If you just came from a suspend/resume,\n" "please switch to the trace global clock:\n" " echo global > /sys/kernel/debug/tracing/trace_clock\n"); - - /* - * Discarding this event to add a timestamp in front, but - * we still need to update the length of it to perform the discard. - */ - rb_update_event(cpu_buffer, event, info); - - if (rb_try_to_discard(cpu_buffer, event)) { - info->add_timestamp = 1; - /* - * The time delta since the last event is too big to - * hold in the time field of the event, then we append a - * TIME EXTEND event ahead of the data event. - */ - info->length += RB_LEN_TIME_EXTEND; - return; - } - - /* - * Humpf! An event came in after this one, and because it is not a - * commit, it will have a delta of zero, thus, it will take on - * the timestamp of the previous commit, which happened a long time - * ago (we need to add a timestamp, remember?). - * We need to add the timestamp here. A timestamp is a fixed size - * of 8 bytes. That means the rest of the event needs to be - * padding. - */ - size = info->length - RB_LEN_TIME_EXTEND; - - /* The padding will have a delta of 1 */ - if (size) - info->delta--; - - padding = rb_add_time_stamp(event, info->delta); - - if (size) { - length = info->length; - info->delta = 0; - info->length = size; - rb_update_event(cpu_buffer, padding, info); - - rb_event_discard(padding); - - /* Still visible, need to update write_stamp */ - rb_update_write_stamp(cpu_buffer, event); - - /* Still need to commit the padding. */ - rb_end_commit(cpu_buffer); - - /* rb_end_commit() decs committing */ - local_inc(&cpu_buffer->committing); - - /* The next iteration still uses the original length */ - info->length = length; - } + info->add_timestamp = 1; } static struct ring_buffer_event * @@ -2765,7 +2696,14 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event; struct buffer_page *tail_page; unsigned long tail, write; - bool is_commit; + + /* + * If the time delta since the last event is too big to + * hold in the time field of the event, then we append a + * TIME EXTEND event ahead of the data event. + */ + if (unlikely(info->add_timestamp)) + info->length += RB_LEN_TIME_EXTEND; tail_page = info->tail_page = cpu_buffer->tail_page; write = local_add_return(info->length, &tail_page->write); @@ -2774,43 +2712,32 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, write &= RB_WRITE_MASK; tail = write - info->length; - /* See if we shot pass the end of this buffer page */ - if (unlikely(write > BUF_PAGE_SIZE)) - return rb_move_tail(cpu_buffer, tail, info); - - /* We reserved something on the buffer */ - event = __rb_page_index(tail_page, tail); - /* * If this is the first commit on the page, then it has the same - * timestamp as the page itself, otherwise we need to figure out - * the delta. + * timestamp as the page itself. */ - info->ts = rb_time_stamp(cpu_buffer->buffer); - is_commit = rb_event_is_commit(cpu_buffer, event); - - /* Commits are special (non nested events) */ - info->delta = is_commit ? info->ts - cpu_buffer->write_stamp : 0; - - if (!tail) { - /* - * If this is the first commit on the page, set the - * page to its timestamp. - */ - tail_page->page->time_stamp = info->ts; + if (!tail) info->delta = 0; - } else if (unlikely(test_time_stamp(info->delta)) && - !info->add_timestamp) { - rb_handle_timestamp(cpu_buffer, event, info); - return ERR_PTR(-EAGAIN); - } + /* See if we shot pass the end of this buffer page */ + if (unlikely(write > BUF_PAGE_SIZE)) + return rb_move_tail(cpu_buffer, tail, info); + /* We reserved something on the buffer */ + + event = __rb_page_index(tail_page, tail); kmemcheck_annotate_bitfield(event, bitfield); rb_update_event(cpu_buffer, event, info); local_inc(&tail_page->entries); + /* + * If this is the first commit on the page, then update + * its timestamp. + */ + if (!tail) + tail_page->page->time_stamp = info->ts; + /* account for these added bytes */ local_add(info->length, &cpu_buffer->entries_bytes); @@ -2825,6 +2752,7 @@ rb_reserve_next_event(struct ring_buffer *buffer, struct ring_buffer_event *event; struct rb_event_info info; int nr_loops = 0; + u64 diff; rb_start_commit(cpu_buffer); @@ -2842,9 +2770,12 @@ rb_reserve_next_event(struct ring_buffer *buffer, return NULL; } #endif + info.length = rb_calculate_event_length(length); - info.add_timestamp = 0; again: + info.add_timestamp = 0; + info.delta = 0; + /* * We allow for interrupts to reenter here and do a trace. * If one does, it will cause this original code to loop @@ -2857,6 +2788,19 @@ rb_reserve_next_event(struct ring_buffer *buffer, if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) goto out_fail; + info.ts = rb_time_stamp(cpu_buffer->buffer); + diff = info.ts - cpu_buffer->write_stamp; + + /* make sure this diff is calculated here */ + barrier(); + + /* Did the write stamp get updated already? */ + if (likely(info.ts >= cpu_buffer->write_stamp)) { + info.delta = diff; + if (unlikely(test_time_stamp(info.delta))) + rb_handle_timestamp(cpu_buffer, &info); + } + event = __rb_reserve_next(cpu_buffer, &info); if (unlikely(PTR_ERR(event) == -EAGAIN)) |
