ring-buffer/tracing: Have iterator acknowledge dropped events (c9b7a4a7) · Commits · 戴 / test

include/linux/ring_buffer.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -138,6 +138,7 @@ ring_buffer_iter_peek(struct ring_buffer_iter iter, u64 ts);
		void ring_buffer_iter_advance(struct ring_buffer_iter *iter);
		void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
		int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
		bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter);

		unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu);

+16 −0

Original line number	Diff line number	Diff line
		@@ -510,6 +510,7 @@ struct ring_buffer_iter {
		u64 read_stamp;
		u64 page_stamp;
		struct ring_buffer_event *event;
		int missed_events;
		};

		/**
		@@ -1988,6 +1989,7 @@ rb_iter_head_event(struct ring_buffer_iter *iter)
		iter->page_stamp = iter->read_stamp = iter->head_page->page->time_stamp;
		iter->head = 0;
		iter->next_event = 0;
		iter->missed_events = 1;
		return NULL;
		}

		@@ -4191,6 +4193,20 @@ ring_buffer_peek(struct trace_buffer buffer, int cpu, u64 ts,
		return event;
		}

		/** ring_buffer_iter_dropped - report if there are dropped events
		* @iter: The ring buffer iterator
		*
		* Returns true if there was dropped events since the last peek.
		*/
		bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter)
		{
		bool ret = iter->missed_events != 0;

		iter->missed_events = 0;
		return ret;
		}
		EXPORT_SYMBOL_GPL(ring_buffer_iter_dropped);

		/**
		* ring_buffer_iter_peek - peek at the next event to be read
		* @iter: The ring buffer iterator

+12 −4

Original line number	Diff line number	Diff line
		@@ -3388,11 +3388,15 @@ peek_next_entry(struct trace_iterator iter, int cpu, u64 ts,
		struct ring_buffer_event *event;
		struct ring_buffer_iter *buf_iter = trace_buffer_iter(iter, cpu);

		if (buf_iter)
		if (buf_iter) {
		event = ring_buffer_iter_peek(buf_iter, ts);
		else
		if (lost_events)
		*lost_events = ring_buffer_iter_dropped(buf_iter) ?
		(unsigned long)-1 : 0;
		} else {
		event = ring_buffer_peek(iter->array_buffer->buffer, cpu, ts,
		lost_events);
		}

		if (event) {
		iter->ent_size = ring_buffer_event_length(event);
		@@ -4005,6 +4009,10 @@ enum print_line_t print_trace_line(struct trace_iterator *iter)
		enum print_line_t ret;

		if (iter->lost_events) {
		if (iter->lost_events == (unsigned long)-1)
		trace_seq_printf(&iter->seq, "CPU:%d [LOST EVENTS]\n",
		iter->cpu);
		else
		trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n",
		iter->cpu, iter->lost_events);
		if (trace_seq_has_overflowed(&iter->seq))