linux-kernel - Re: [PATCH] tracing: react to error return from traceprobe_parse_event

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Date:   Thu, 11 Aug 2022 07:28:03 +0800
From:   Linyu Yuan <quic_linyyuan@...cinc.com>
To:     Lukas Bulwahn <lukas.bulwahn@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Tom Zanussi <zanussi@...nel.org>
CC:     <kernel-janitors@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] tracing: react to error return from
 traceprobe_parse_event_name()

hi Lukas,

On 8/10/2022 11:09 PM, Lukas Bulwahn wrote:
> The function traceprobe_parse_event_name() may set the first two function
> arguments to a non-null value and still return -EINVAL to indicate an
> unsuccessful completion of the function. Hence, it is not sufficient to
> just check the result of the two function arguments for being not null,
> but the return value also needs to be checked.
>
> Commit 95c104c378dc ("tracing: Auto generate event name when creating a
> group of events") changed the error-return-value checking of the second
> traceprobe_parse_event_name() invocation in __trace_eprobe_create() and
> removed checking the return value to jump to the error handling case.
>
> Reinstate using the return value in the error-return-value checking.
>
> Signed-off-by: Lukas Bulwahn <lukas.bulwahn@...il.com>
> ---
>   kernel/trace/trace_eprobe.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
> index 4a0e9d927443..460d3ec8a256 100644
> --- a/kernel/trace/trace_eprobe.c
> +++ b/kernel/trace/trace_eprobe.c
> @@ -883,7 +883,7 @@ static int __trace_eprobe_create(int argc, const char *argv[])
>   	trace_probe_log_set_index(1);
>   	sys_event = argv[1];
>   	ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2, 0);
> -	if (!sys_event || !sys_name) {
> +	if (!ret || !sys_event || !sys_name) {

that's right, miss case sys_event and sys_name are not null, but invalid.

it should be  if (ret || ...)  ?


>   		trace_probe_log_err(0, NO_EVENT_INFO);
>   		goto parse_error;
>   	}