linux-kernel - Re: [PATCH] opp: Allow dev_pm_opp_set

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Date:   Thu, 28 Jan 2021 09:51:31 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH] opp: Allow dev_pm_opp_set_opp() to be called without opp

On 27-01-21, 20:04, Bjorn Andersson wrote:
> a6xx_gmu_stop() calls dev_pm_opp_set_opp() with NULL as opp in order to
> drop its bandwidth request, which was valid with dev_pm_opp_set_bw().
> But after the transition to dev_pm_opp_set_opp() this leads to a NULL
> dereference before jumping into _set_opp(), which does disable the
> vote as expected.
> 
> Fixes: a0d67b94e2ef ("opp: Implement dev_pm_opp_set_opp()")
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
>  drivers/opp/core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 583bb1274df9..3ff05f40e443 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -1157,7 +1157,7 @@ int dev_pm_opp_set_opp(struct device *dev, struct dev_pm_opp *opp)
>  		return PTR_ERR(opp_table);
>  	}
>  
> -	ret = _set_opp(dev, opp_table, opp, opp->rate);
> +	ret = _set_opp(dev, opp_table, opp, opp ? opp->rate : 0);
>  	dev_pm_opp_put_opp_table(opp_table);
>  
>  	return ret;

I specially handled this case with care and still missed this :(

I have updated the original patch to fix it, thanks.

-- 
viresh