linux-kernel - Re: [PATCH] scsi: ufs: qcom: Drop dead compile guard

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Message-ID: <CAKXUXMzgABnN3bbV58xVwYNithcUg7fZgW0DxGCngJnNgNzrfw@mail.gmail.com>
Date: Tue, 5 Aug 2025 06:45:27 +0200
From: Lukas Bulwahn <lukas.bulwahn@...il.com>
To: Dan Carpenter <dan.carpenter@...aro.org>
Cc: Konrad Dybcio <konradybcio@...nel.org>, kernel-janitors@...r.kernel.org, 
	Julia Lawall <julia.lawall@...6.fr>, Manivannan Sadhasivam <mani@...nel.org>, 
	"James E.J. Bottomley" <James.Bottomley@...senpartnership.com>, 
	"Martin K. Petersen" <martin.petersen@...cle.com>, Marijn Suijten <marijn.suijten@...ainline.org>, 
	linux-arm-msm@...r.kernel.org, linux-scsi@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Subject: Re: [PATCH] scsi: ufs: qcom: Drop dead compile guard

On Fri, Aug 1, 2025 at 5:33 PM Dan Carpenter <dan.carpenter@...aro.org> wrote:
>
> This patch removes some dead ifdeffed code because the KConfig has a
> select which ensures that CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND is set.
> Konrad was wondering if there are any tools to detect this sort of
> thing.  I don't think so.  I think the only thing we detect are
> non-existant configs.  But let me add a few more people to the CC who
> might know.
>

I also have a simple script to search for unused configs, but that is
just five lines of bash and then a lot of manual filtering.

If I would attempt to implement such already rather complex analysis,
I would start with looking at this tool:

https://github.com/paulgazz/kmax

Possibly, there is a good way to re-use some parts of it or extend it
to look for the pattern above.

Lukas

> regards,
> dan carpenter
>
> On Thu, Jul 24, 2025 at 02:23:52PM +0200, Konrad Dybcio wrote:
> > From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
> >
> > SCSI_UFSHCD already selects DEVFREQ_GOV_SIMPLE_ONDEMAND, drop the
> > check.
> >
> > Signed-off-by: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
> > ---
> > Is this something that could be discovered by our existing static
> > checkers?
> > ---
> >  drivers/ufs/host/ufs-qcom.c | 8 --------
> >  1 file changed, 8 deletions(-)
> >
> > diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
> > index 4bbe4de1679b908c85e6a3d4035fc9dcafcc0d1a..76fc70503a62eb2e747b2d4cd18cc05b6f5526c7 100644
> > --- a/drivers/ufs/host/ufs-qcom.c
> > +++ b/drivers/ufs/host/ufs-qcom.c
> > @@ -1898,7 +1898,6 @@ static int ufs_qcom_device_reset(struct ufs_hba *hba)
> >       return 0;
> >  }
> >
> > -#if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
> >  static void ufs_qcom_config_scaling_param(struct ufs_hba *hba,
> >                                       struct devfreq_dev_profile *p,
> >                                       struct devfreq_simple_ondemand_data *d)
> > @@ -1910,13 +1909,6 @@ static void ufs_qcom_config_scaling_param(struct ufs_hba *hba,
> >
> >       hba->clk_scaling.suspend_on_no_request = true;
> >  }
> > -#else
> > -static void ufs_qcom_config_scaling_param(struct ufs_hba *hba,
> > -             struct devfreq_dev_profile *p,
> > -             struct devfreq_simple_ondemand_data *data)
> > -{
> > -}
> > -#endif
> >
> >  /* Resources */
> >  static const struct ufshcd_res_info ufs_res_info[RES_MAX] = {
> >
> > ---
> > base-commit: a933d3dc1968fcfb0ab72879ec304b1971ed1b9a
> > change-id: 20250724-topic-ufs_compile_check-3378996f4221
> >
> > Best regards,
> > --
> > Konrad Dybcio <konrad.dybcio@....qualcomm.com>