blktrace: fix context-info when mixed-using blk tracer and trace events (f3948f88) · Commits · 戴 / test

When current tracer is set to blk tracer, TRACE_ITER_CONTEXT_INFO is unset, but actually context-info is printed: pdflush-431 [000] 821.181576: 8,0 P N [pdflush] And then if we enable TRACE_ITER_CONTEXT_INFO: # echo context-info > trace_options We'll see context-info printed twice. What's worse, when we use blk tracer and trace events at the same time, we'll see no context-info for trace events at all: jbd2_commit_logging: dev dm-0:8 transaction 333227 jbd2_end_commit: dev dm-0:8 transaction 333227 head 332814 rm-25433 [001] 9578.307485: 8,18 m N cfq25433 slice expired t=0 rm-25433 [001] 9578.307486: 8,18 m N cfq25433 put_queue This patch adds blk_tracer->set_flags(), and context-info flag is unset only when we set the output to classic mode. Note after this patch, one should unset context-info explicitly if he wants to get binary output that can be parsed by blkparse: # echo nocontext-info > trace_options # echo bin > trace_options # echo blk > current_tracer # cat trace_pipe | blkparse -i - Reported-by:

Theodore Ts'o <tytso@mit.edu> Signed-off-by:

Li Zefan <lizf@cn.fujitsu.com> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <49E54E60.50408@cn.fujitsu.com> Signed-off-by:

Ingo Molnar <mingo@elte.hu>

kernel/trace/blktrace.c

+13 −5

Original line number	Diff line number	Diff line
		@@ -1211,7 +1211,6 @@ static void blk_tracer_print_header(struct seq_file *m)
		static void blk_tracer_start(struct trace_array *tr)
		{
		blk_tracer_enabled = true;
		trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
		}

		static int blk_tracer_init(struct trace_array *tr)
		@@ -1224,7 +1223,6 @@ static int blk_tracer_init(struct trace_array *tr)
		static void blk_tracer_stop(struct trace_array *tr)
		{
		blk_tracer_enabled = false;
		trace_flags \|= TRACE_ITER_CONTEXT_INFO;
		}

		static void blk_tracer_reset(struct trace_array *tr)
		@@ -1289,9 +1287,6 @@ out:
		static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
		int flags)
		{
		if (!trace_print_context(iter))
		return TRACE_TYPE_PARTIAL_LINE;

		return print_one_line(iter, false);
		}

		@@ -1326,6 +1321,18 @@ static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
		return print_one_line(iter, true);
		}

		static int blk_tracer_set_flag(u32 old_flags, u32 bit, int set)
		{
		/* don't output context-info for blk_classic output */
		if (bit == TRACE_BLK_OPT_CLASSIC) {
		if (set)
		trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
		else
		trace_flags \|= TRACE_ITER_CONTEXT_INFO;
		}
		return 0;
		}

		static struct tracer blk_tracer __read_mostly = {
		.name = "blk",
		.init = blk_tracer_init,
		@@ -1335,6 +1342,7 @@ static struct tracer blk_tracer __read_mostly = {
		.print_header = blk_tracer_print_header,
		.print_line = blk_tracer_print_line,
		.flags = &blk_tracer_flags,
		.set_flag = blk_tracer_set_flag,
		};

		static struct trace_event trace_blk_event = {

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