linux-kernel - Re: [PATCH] tracepoint: Allow trace events in modules with TAINT

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Message-ID: <Ywle+96kZr5Y6Kn/@aschofie-mobl2>
Date:   Fri, 26 Aug 2022 17:02:03 -0700
From:   Alison Schofield <alison.schofield@...el.com>
To:     Steven Rostedt <rostedt@...dmis.org>,
        David Gow <davidgow@...gle.com>
Cc:     linux-kernel@...r.kernel.org, linux-cxl@...r.kernel.org,
        Ira Weiny <ira.weiny@...el.com>,
        Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH] tracepoint: Allow trace events in modules with TAINT_TEST

+ David Gow - Submitter of the new taint type

On Fri, Aug 26, 2022 at 03:35:11PM -0700, alison.schofield@...el.com wrote:
> From: Alison Schofield <alison.schofield@...el.com>
> 
> Commit 2852ca7fba9f ("panic: Taint kernel if tests are run")
> introduced a new taint type, TAINT_TEST, to signal that an
> in-kernel test has been run.
> 
> TAINT_TEST taint type defaults into a 'bad_taint' list for
> kernel tracing and blocks the creation of trace events. This
> causes a problem for CXL testing where loading the cxl_test
> module makes all CXL modules out-of-tree, blocking any trace
> events.
> 
> Trace events are in development for CXL at the moment and this
> issue was found in test with v6.0-rc1.
> 
> Reported-by: Ira Weiny <ira.weiny@...el.com>
> Suggested-by: Dan Williams <dan.j.williams@...el.com>
> Signed-off-by: Alison Schofield <alison.schofield@...el.com>
> ---
>  kernel/tracepoint.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
> index 64ea283f2f86..5f17378c9dc2 100644
> --- a/kernel/tracepoint.c
> +++ b/kernel/tracepoint.c
> @@ -571,7 +571,8 @@ static void for_each_tracepoint_range(
>  bool trace_module_has_bad_taint(struct module *mod)
>  {
>  	return mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP) |
> -			       (1 << TAINT_UNSIGNED_MODULE));
> +			       (1 << TAINT_UNSIGNED_MODULE) |
> +			       (1 << TAINT_TEST));
>  }
>  
>  static BLOCKING_NOTIFIER_HEAD(tracepoint_notify_list);
> 
> base-commit: 4c612826bec1441214816827979b62f84a097e91
> -- 
> 2.31.1
>