[PATCH] blktrace: Fix output non-blktrace event when blk_classic option enabled

From: Yang Jihong <yangjihong1@huawei.com>
To: <axboe@kernel.dk>, <rostedt@goodmis.org>, <mhiramat@kernel.org>,
	<acme@redhat.com>, <mingo@elte.hu>, <linux-block@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>
Cc: <yangjihong1@huawei.com>
Subject: [PATCH] blktrace: Fix output non-blktrace event when blk_classic option enabled
Date: Tue, 22 Nov 2022 12:04:10 +0800	[thread overview]
Message-ID: <20221122040410.85113-1-yangjihong1@huawei.com> (raw)

When the blk_classic option is enabled, non-blktrace events must be
filtered out. Otherwise, events of other types are output in the blktrace
classic format, which is unexpected.

The problem can be triggered in the following ways:

  # echo 1 > /sys/kernel/debug/tracing/options/blk_classic
  # echo 1 > /sys/kernel/debug/tracing/events/enable
  # echo blk > /sys/kernel/debug/tracing/current_tracer
  # cat /sys/kernel/debug/tracing/trace_pipe

Fixes: c71a89615411 ("blktrace: add ftrace plugin")
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
---
 kernel/trace/blktrace.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index a995ea1ef849..a66cff5a1857 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -1548,7 +1548,8 @@ blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
 
 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
 {
-	if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
+	if ((iter->ent->type != TRACE_BLK) ||
+	    !(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
 		return TRACE_TYPE_UNHANDLED;
 
 	return print_one_line(iter, true);
-- 
2.30.GIT

