linux-kernel - Re: [PATCH 4/8 v4] thermal: rcar: retern error rcar_thermal_get

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Date:	Mon, 14 Dec 2015 23:55:30 +0000
From:	Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
To:	Eduardo Valentin <edubezval@...il.com>
CC:	Simon <horms@...ge.net.au>, Zhang Rui <rui.zhang@...el.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Magnus <magnus.damm@...il.com>, <linux-sh@...r.kernel.org>,
	<linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH 4/8 v4] thermal: rcar: retern error rcar_thermal_get_temp() if no ctemp update


Hi Eduardo

> > --- a/drivers/thermal/rcar_thermal.c
> > +++ b/drivers/thermal/rcar_thermal.c
> > @@ -199,9 +199,9 @@ static int rcar_thermal_update_temp(struct rcar_thermal_priv *priv)
> >  
> >  	dev_dbg(dev, "thermal%d  %d -> %d\n", priv->id, priv->ctemp, ctemp);
> >  
> > -	priv->ctemp = ctemp;
> >  	ret = 0;
> >  err_out_unlock:
> > +	priv->ctemp = ctemp;
> >  	mutex_unlock(&priv->lock);
> >  	return ret;
> 
> I believe the problem here is actually the lack of error
> handling/propagation. Are you sure you want to write to parameter
> in the fail path ?
> 
> rcar_thermal_update_temp already returns error code when it fails
> to read temperature. Don't you think it would make more sense to fix the
> places that call rcar_thermal_update_temp to properly handle its return
> value and propagate that error code when necessary?

Thanks. But the logic is that
priv->ctemp will be 0 in error cases, and it will be reported as
dev_err() in rcar_thermal_get_current_temp()

The problem was that priv->ctemp will not be updated
in error case of rcar_thermal_update_temp().
but user can call get_temp (it doesn't call
rcar_thermal_update_temp() if interrupt was supported).
In such case, user will get old thermal.

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