linux-kernel - Re: [PATCH v2 21/27] coresight: Convert driver messages to dev

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Message-Id: <20180501225503.a55fb963795afb40163f3763@arm.com>
Date:   Tue, 1 May 2018 22:55:03 -0500
From:   Kim Phillips <kim.phillips@....com>
To:     Suzuki K Poulose <suzuki.poulose@....com>
Cc:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <mathieu.poirier@...aro.org>,
        <mike.leach@...aro.org>, <robert.walker@....com>,
        <mark.rutland@....com>, <will.deacon@....com>,
        <robin.murphy@....com>, <sudeep.holla@....com>,
        <frowand.list@...il.com>, <robh@...nel.org>, <john.horley@....com>
Subject: Re: [PATCH v2 21/27] coresight: Convert driver messages to dev_dbg

On Tue, 1 May 2018 10:10:51 +0100
Suzuki K Poulose <suzuki.poulose@....com> wrote:

> Convert component enable/disable messages from dev_info to dev_dbg.
> This is required to prevent LOCKDEP splats when operating in perf
> mode where we could be called with locks held to enable a coresight

Can we see the splats?  Doesn't lockdep turn itself off if it starts
triggering too many splats?

> path. If someone wants to really see the messages, they can always
> enable it at runtime via dynamic_debug.

Won't the splats still occur when the messages are enabled with
dynamic_debug?

So in effect this patch only tries to mitigate the splats, all the
while making things harder for regular users that now have to recompile
their kernels, in exchange for a very small convenience for kernel
developers that happen to see a splat or two with DEBUG_LOCKDEP set?

Not the greatest choice...How about moving the dev_infos outside of the
locks instead?

Thanks,

Kim