linux-kernel - Re: [PATCH] soc: qcom: rpmh-rsc: Set suppress_bind

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Date:   Mon, 22 Jun 2020 12:29:32 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Maulik Shah <mkshah@...eaurora.org>, agross@...nel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        dianders@...omium.org, rnayak@...eaurora.org, ilina@...eaurora.org,
        lsrao@...eaurora.org, john.stultz@...aro.org
Subject: Re: [PATCH] soc: qcom: rpmh-rsc: Set suppress_bind_attrs flag

On Mon 22 Jun 02:03 PDT 2020, Stephen Boyd wrote:

> Quoting Maulik Shah (2020-06-21 23:53:25)
> > rpmh-rsc driver is fairly core to system and should not be removable
> > once its probed. However it allows to unbind driver from sysfs using
> > below command which results into a crash on sc7180.
> 
> What is the crash? The world falls apart because rpmh APIs start
> referencing pointers that point to freed memory?
> 

Presumably the devm_of_platform_populate() will cause said drivers to be
dismantled as well - but I think it's safe to say that that code path
isn't well tested...

I've applied the patch, but would have preferred that some time was
spent to make sure that things are unloadable as well.

Regards,
Bjorn

> > 
> > echo 18200000.rsc > /sys/bus/platform/drivers/rpmh/unbind
> > 
> > Lets prevent unbind at runtime by setting suppress_bind_attrs flag.
> 
> Ok. But when the Android module brigade comes knocking they'll have to
> revert this change and solve this problem too. Have fun!
> 
> > 
> > Signed-off-by: Maulik Shah <mkshah@...eaurora.org>
> > ---
> 
> Reviewed-by: Stephen Boyd <swboyd@...omium.org>