netdev - Re: [PATCH] random32: Use rcuidle variant for tracepoint

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Message-ID: <20200821085907.GJ1362448@hirez.programming.kicks-ass.net>
Date:   Fri, 21 Aug 2020 10:59:07 +0200
From:   peterz@...radead.org
To:     Marco Elver <elver@...gle.com>
Cc:     linux-kernel@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
        netdev@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
        Eric Dumazet <edumazet@...gle.com>
Subject: Re: [PATCH] random32: Use rcuidle variant for tracepoint

On Fri, Aug 21, 2020 at 08:30:43AM +0200, Marco Elver wrote:
> With KCSAN enabled, prandom_u32() may be called from any context,
> including idle CPUs.
> 
> Therefore, switch to using trace_prandom_u32_rcuidle(), to avoid various
> issues due to recursion and lockdep warnings when KCSAN and tracing is
> enabled.

At some point we're going to have to introduce noinstr to idle as well.
But until that time this should indeed cure things.