linux-kernel - Re: [PATCH] blktrace: Fix output non-blktrace event when blk

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Message-ID: <e5654353-9850-beb5-cf72-7a7473a14743@huawei.com>
Date:   Wed, 7 Dec 2022 09:34:57 +0800
From:   Yang Jihong <yangjihong1@...wei.com>
To:     <axboe@...nel.dk>, <rostedt@...dmis.org>, <mhiramat@...nel.org>,
        <acme@...hat.com>, <mingo@...e.hu>, <linux-block@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] blktrace: Fix output non-blktrace event when blk_classic
 option enabled

Hello,

PING.

Thanks,
Yang.

On 2022/11/22 12:04, Yang Jihong wrote:
> 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@...wei.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);
>