[PATCH] mtd: Fix misuses of of_match_ptr()

Paul Cercueil paul at crapouillou.net
Thu Jan 27 03:35:16 PST 2022 


Le jeu., janv. 27 2022 at 12:32:05 +0100, Alexandre Belloni 
<alexandre.belloni at bootlin.com> a écrit :
> 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.

Fair enough. I didn't think about this use-case.

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

More information about the linux-mtd mailing list