[PATCH] mtd: Fix misuses of of_match_ptr()

Alexandre Belloni alexandre.belloni at bootlin.com
Thu Jan 27 03:32:05 PST 2022 

On 27/01/2022 11:18:27+0000, Paul Cercueil wrote:
> Hi Miquel,
> 
> Le jeu., janv. 27 2022 at 12:06:31 +0100, Miquel Raynal
> <miquel.raynal at bootlin.com> a écrit :
> > of_match_ptr() either expands to NULL if !CONFIG_OF, or is transparent
> > otherwise. There are several drivers using this macro which keep their
> > of_device_id array enclosed within an #ifdef CONFIG_OF check, these are
> > considered fine. However, When misused, the of_device_id array pointed
> > by this macro will produce a warning because it is finally unused when
> > compiled without OF support.
> > 
> > A number of fixes are possible:
> > - Always depend on CONFIG_OF, but this will not always work and may
> >   break boards.
> > - Enclose the compatible array by #ifdef's, this may save a bit of
> >   memory but will reduce build coverage.
> > - Tell the compiler the array may be unused, if this can be avoided,
> >   let's not do this.
> > - Just drop the macro, setting the of_device_id array for a non OF
> >   enabled platform is not an issue, it will just be unused.
> > 
> > The latter solution seems the more appropriate, so let's use it.
> 
> I disagree. The proper solution would be to not have of_match_ptr()
> conditionally defined.
> 

I disagree...

> Right now it's defined basically like this:
> #ifdef CONFIG_OF
> #define of_match_ptr(_ptr) (_ptr)
> #else
> #define of_match_ptr(_ptr) NULL
> #endif
> 
> This is bad, because in the !CONFIG_OF case, the pointer is never
> referenced, and the compiler complains about it, as you can notice.
> 
> Instead, it should be defined like this:
> #define of_match_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_OF), (_ptr))
> 
> Then in the !CONFIG_OF case the compiler will see the array as effectively
> unused, and drop it as needed.
> 
> We are doing the exact same work with the PM callbacks, with the new
> pm_ptr() macro.
> 
> Note that I don't know the behaviour of MODULE_DEVICE_TABLE(of, ...), it
> might be a good idea to make it a NOP if !CONFIG_OF so that the array is
> removed by the compiler as dead code (if it's not the case already).
> 

... because ACPI platforms can use the OF table to probe drivers even
when they don't have OF support.

> Cheers,
> -Paul
> 
> > 
> > Reported-by: kernel test robot <lkp at intel.com>
> > Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
> > ---
> >  drivers/mtd/devices/mchp23k256.c                | 2 +-
> >  drivers/mtd/devices/mchp48l640.c                | 2 +-
> >  drivers/mtd/nand/raw/atmel/nand-controller.c    | 2 +-
> >  drivers/mtd/nand/raw/atmel/pmecc.c              | 2 +-
> >  drivers/mtd/nand/raw/ingenic/ingenic_nand_drv.c | 2 +-
> >  drivers/mtd/nand/raw/ingenic/jz4780_bch.c       | 2 +-
> >  drivers/mtd/nand/raw/mtk_ecc.c                  | 2 +-
> >  drivers/mtd/nand/raw/omap2.c                    | 2 +-
> >  drivers/mtd/nand/raw/renesas-nand-controller.c  | 2 +-
> >  drivers/mtd/nand/raw/sh_flctl.c                 | 2 +-
> >  10 files changed, 10 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/mtd/devices/mchp23k256.c
> > b/drivers/mtd/devices/mchp23k256.c
> > index a8b31bddf14b..bf51eebf052c 100644
> > --- a/drivers/mtd/devices/mchp23k256.c
> > +++ b/drivers/mtd/devices/mchp23k256.c
> > @@ -234,7 +234,7 @@ MODULE_DEVICE_TABLE(of, mchp23k256_of_table);
> >  static struct spi_driver mchp23k256_driver = {
> >  	.driver = {
> >  		.name	= "mchp23k256",
> > -		.of_match_table = of_match_ptr(mchp23k256_of_table),
> > +		.of_match_table = mchp23k256_of_table,
> >  	},
> >  	.probe		= mchp23k256_probe,
> >  	.remove		= mchp23k256_remove,
> > diff --git a/drivers/mtd/devices/mchp48l640.c
> > b/drivers/mtd/devices/mchp48l640.c
> > index 231a10790196..4ec505b3f4a6 100644
> > --- a/drivers/mtd/devices/mchp48l640.c
> > +++ b/drivers/mtd/devices/mchp48l640.c
> > @@ -362,7 +362,7 @@ MODULE_DEVICE_TABLE(of, mchp48l640_of_table);
> >  static struct spi_driver mchp48l640_driver = {
> >  	.driver = {
> >  		.name	= "mchp48l640",
> > -		.of_match_table = of_match_ptr(mchp48l640_of_table),
> > +		.of_match_table = mchp48l640_of_table,
> >  	},
> >  	.probe		= mchp48l640_probe,
> >  	.remove		= mchp48l640_remove,
> > diff --git a/drivers/mtd/nand/raw/atmel/nand-controller.c
> > b/drivers/mtd/nand/raw/atmel/nand-controller.c
> > index f3276ee9e4fe..4ecbaccf5526 100644
> > --- a/drivers/mtd/nand/raw/atmel/nand-controller.c
> > +++ b/drivers/mtd/nand/raw/atmel/nand-controller.c
> > @@ -2648,7 +2648,7 @@ static
> > SIMPLE_DEV_PM_OPS(atmel_nand_controller_pm_ops, NULL,
> >  static struct platform_driver atmel_nand_controller_driver = {
> >  	.driver = {
> >  		.name = "atmel-nand-controller",
> > -		.of_match_table = of_match_ptr(atmel_nand_controller_of_ids),
> > +		.of_match_table = atmel_nand_controller_of_ids,
> >  		.pm = &atmel_nand_controller_pm_ops,
> >  	},
> >  	.probe = atmel_nand_controller_probe,
> > diff --git a/drivers/mtd/nand/raw/atmel/pmecc.c
> > b/drivers/mtd/nand/raw/atmel/pmecc.c
> > index 498e41ccabbd..43ebd78816c0 100644
> > --- a/drivers/mtd/nand/raw/atmel/pmecc.c
> > +++ b/drivers/mtd/nand/raw/atmel/pmecc.c
> > @@ -1003,7 +1003,7 @@ static int atmel_pmecc_probe(struct
> > platform_device *pdev)
> >  static struct platform_driver atmel_pmecc_driver = {
> >  	.driver = {
> >  		.name = "atmel-pmecc",
> > -		.of_match_table = of_match_ptr(atmel_pmecc_match),
> > +		.of_match_table = atmel_pmecc_match,
> >  	},
> >  	.probe = atmel_pmecc_probe,
> >  };
> > diff --git a/drivers/mtd/nand/raw/ingenic/ingenic_nand_drv.c
> > b/drivers/mtd/nand/raw/ingenic/ingenic_nand_drv.c
> > index b18861bdcdc8..ff26c10f295d 100644
> > --- a/drivers/mtd/nand/raw/ingenic/ingenic_nand_drv.c
> > +++ b/drivers/mtd/nand/raw/ingenic/ingenic_nand_drv.c
> > @@ -567,7 +567,7 @@ static struct platform_driver ingenic_nand_driver =
> > {
> >  	.remove		= ingenic_nand_remove,
> >  	.driver	= {
> >  		.name	= DRV_NAME,
> > -		.of_match_table = of_match_ptr(ingenic_nand_dt_match),
> > +		.of_match_table = ingenic_nand_dt_match,
> >  	},
> >  };
> >  module_platform_driver(ingenic_nand_driver);
> > diff --git a/drivers/mtd/nand/raw/ingenic/jz4780_bch.c
> > b/drivers/mtd/nand/raw/ingenic/jz4780_bch.c
> > index d67dbfff76cc..12b5b0484fe9 100644
> > --- a/drivers/mtd/nand/raw/ingenic/jz4780_bch.c
> > +++ b/drivers/mtd/nand/raw/ingenic/jz4780_bch.c
> > @@ -260,7 +260,7 @@ static struct platform_driver jz4780_bch_driver = {
> >  	.probe		= jz4780_bch_probe,
> >  	.driver	= {
> >  		.name	= "jz4780-bch",
> > -		.of_match_table = of_match_ptr(jz4780_bch_dt_match),
> > +		.of_match_table = jz4780_bch_dt_match,
> >  	},
> >  };
> >  module_platform_driver(jz4780_bch_driver);
> > diff --git a/drivers/mtd/nand/raw/mtk_ecc.c
> > b/drivers/mtd/nand/raw/mtk_ecc.c
> > index 1b47964cb6da..e7df3dac705e 100644
> > --- a/drivers/mtd/nand/raw/mtk_ecc.c
> > +++ b/drivers/mtd/nand/raw/mtk_ecc.c
> > @@ -579,7 +579,7 @@ static struct platform_driver mtk_ecc_driver = {
> >  	.probe  = mtk_ecc_probe,
> >  	.driver = {
> >  		.name  = "mtk-ecc",
> > -		.of_match_table = of_match_ptr(mtk_ecc_dt_match),
> > +		.of_match_table = mtk_ecc_dt_match,
> >  #ifdef CONFIG_PM_SLEEP
> >  		.pm = &mtk_ecc_pm_ops,
> >  #endif
> > diff --git a/drivers/mtd/nand/raw/omap2.c b/drivers/mtd/nand/raw/omap2.c
> > index f0bbbe401e76..58c32a11792e 100644
> > --- a/drivers/mtd/nand/raw/omap2.c
> > +++ b/drivers/mtd/nand/raw/omap2.c
> > @@ -2298,7 +2298,7 @@ static struct platform_driver omap_nand_driver = {
> >  	.remove		= omap_nand_remove,
> >  	.driver		= {
> >  		.name	= DRIVER_NAME,
> > -		.of_match_table = of_match_ptr(omap_nand_ids),
> > +		.of_match_table = omap_nand_ids,
> >  	},
> >  };
> > 
> > diff --git a/drivers/mtd/nand/raw/renesas-nand-controller.c
> > b/drivers/mtd/nand/raw/renesas-nand-controller.c
> > index 428e08362956..6db063b230a9 100644
> > --- a/drivers/mtd/nand/raw/renesas-nand-controller.c
> > +++ b/drivers/mtd/nand/raw/renesas-nand-controller.c
> > @@ -1412,7 +1412,7 @@ MODULE_DEVICE_TABLE(of, rnandc_id_table);
> >  static struct platform_driver rnandc_driver = {
> >  	.driver = {
> >  		.name = "renesas-nandc",
> > -		.of_match_table = of_match_ptr(rnandc_id_table),
> > +		.of_match_table = rnandc_id_table,
> >  	},
> >  	.probe = rnandc_probe,
> >  	.remove = rnandc_remove,
> > diff --git a/drivers/mtd/nand/raw/sh_flctl.c
> > b/drivers/mtd/nand/raw/sh_flctl.c
> > index 13df4bdf792a..b85b9c6fcc42 100644
> > --- a/drivers/mtd/nand/raw/sh_flctl.c
> > +++ b/drivers/mtd/nand/raw/sh_flctl.c
> > @@ -1220,7 +1220,7 @@ static struct platform_driver flctl_driver = {
> >  	.remove		= flctl_remove,
> >  	.driver = {
> >  		.name	= "sh_flctl",
> > -		.of_match_table = of_match_ptr(of_flctl_match),
> > +		.of_match_table = of_flctl_match,
> >  	},
> >  };
> > 
> > --
> > 2.27.0
> > 
> 
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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