linux-kernel - Re: [PATCH 0/7] kcsan: Introduce CONFIG_KCSAN

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Message-ID: <20210615203951.GU4397@paulmck-ThinkPad-P17-Gen-1>
Date:   Tue, 15 Jun 2021 13:39:51 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Marco Elver <elver@...gle.com>
Cc:     Mark Rutland <mark.rutland@....com>, boqun.feng@...il.com,
        will@...nel.org, glider@...gle.com, dvyukov@...gle.com,
        kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/7] kcsan: Introduce CONFIG_KCSAN_PERMISSIVE

On Tue, Jun 15, 2021 at 08:51:18PM +0200, Marco Elver wrote:
> On Tue, Jun 15, 2021 at 11:19AM -0700, Paul E. McKenney wrote:
> [...]
> > Queued and pushed for v5.15, thank you both!
> > 
> > I also queued the following patch making use of CONFIG_KCSAN_STRICT, and I
> > figured that I should run it past you guys to make check my understanding.
> > 
> > Thoughts?
> 
> You still need CONFIG_KCSAN_INTERRUPT_WATCHER=y, but otherwise looks
> good.

I knew I was missing something...  :-/

> I thought I'd leave that out for now, but now thinking about it, we
> might as well imply interruptible watchers. If you agree, feel free to
> queue the below patch ahead of yours.

That works for me!  I have queued the patch below and rebased it to
precede my change to the torture-test infrastructure.

							Thanx, Paul

> Thanks,
> -- Marco
> 
> ------ >8 ------
> 
> From: Marco Elver <elver@...gle.com>
> Date: Tue, 15 Jun 2021 20:39:38 +0200
> Subject: [PATCH] kcsan: Make strict mode imply interruptible watchers
> 
> If CONFIG_KCSAN_STRICT=y, select CONFIG_KCSAN_INTERRUPT_WATCHER as well.
> 
> With interruptible watchers, we'll also report same-CPU data races; if
> we requested strict mode, we might as well show these, too.
> 
> Suggested-by: Paul E. McKenney <paulmck@...nel.org>
> Signed-off-by: Marco Elver <elver@...gle.com>
> ---
>  lib/Kconfig.kcsan | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan
> index 26f03c754d39..e0a93ffdef30 100644
> --- a/lib/Kconfig.kcsan
> +++ b/lib/Kconfig.kcsan
> @@ -150,7 +150,8 @@ config KCSAN_SKIP_WATCH_RANDOMIZE
>  	  KCSAN_WATCH_SKIP.
>  
>  config KCSAN_INTERRUPT_WATCHER
> -	bool "Interruptible watchers"
> +	bool "Interruptible watchers" if !KCSAN_STRICT
> +	default KCSAN_STRICT
>  	help
>  	  If enabled, a task that set up a watchpoint may be interrupted while
>  	  delayed. This option will allow KCSAN to detect races between
> -- 
> 2.32.0.272.g935e593368-goog
>