blktrace: Fix output non-blktrace event when blk_classic option enabled

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>
Link: https://lore.kernel.org/r/20221122040410.85113-1-yangjihong1@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 94fde027bfc0cd4ed26949dd5c235a2f8b9084a6..918a7d12df8ff6315fa1883b8197f800352891b6 100644 (file)
--- 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);