linux-kernel - Re: [RFC PATCH v4 5/7] sched, tracing: add to report task state in symbolic chars

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Message-ID: <20230802224849.215b96b0@gandalf.local.home>
Date:   Wed, 2 Aug 2023 22:48:49 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Ze Gao <zegao2021@...il.com>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Ingo Molnar <mingo@...hat.com>, Jiri Olsa <jolsa@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        linux-trace-kernel@...r.kernel.org,
        linux-trace-devel@...r.kernel.org, Ze Gao <zegao@...cent.com>
Subject: Re: [RFC PATCH v4 5/7] sched, tracing: add to report task state in
 symbolic chars

On Thu, 3 Aug 2023 10:38:43 +0800
Ze Gao <zegao2021@...il.com> wrote:

> > > +static inline char __trace_sched_switch_state_char(bool preempt,
> > > +                                                unsigned int prev_state,
> > > +                                                struct task_struct *p)
> > > +{
> > > +     long state;
> > > +
> > > +#ifdef CONFIG_SCHED_DEBUG
> > > +     BUG_ON(p != current);  
> >
> > BUG? Why not WARN_ON()?  
> 
> I directly copied it from __trace_sched_switch_state since they
> are very similar. I had doubt on this too but decided to keep it in
> case people want to be 100% sure that the current task is exactly
> the one that is being switched, otherwise it's a fatal problem for
> scheduler at the point where trace_sched_switch is called.
> 
> If you think WARN_ON_ONCE is more appropriate, I can fix both
> in v6.
> 
> Thoughts?

Yeah, that BUG_ON is from 2014, and really should not BUG.

I'd fix both.

Thanks!

-- Steve