Re: [PATCH v3 1/3] fpga: mgr: Use standard dev_release for class driver

[Tom Rix <trix@redhat.com>]

Russ,

I think the signature fpga_mgr_register, should change to

int fpga_mgr_register(struct device *, const struct fpga_mager_ops 
*mops, void *priv);

I'll explain below ..

On 5/24/21 11:50 AM, Russ Weight wrote:
> The FPGA manager class driver data structure is being treated as a
> managed resource instead of using standard dev_release call-back
> to release the class data structure. This change removes the
> managed resource code for the freeing of the class data structure
> and combines the create() and register() functions into a single
> register() function.
>
> The devm_fpga_mgr_register() function is retained.
>
> Signed-off-by: Russ Weight <russell.h.weight@intel.com>
> ---
> v3:
>    - Cleaned up comment header for fpga_mgr_register()
>    - Fix error return on ida_simple_get() failure
> v2:
>    - Restored devm_fpga_mgr_register() functionality, adapted for the combined
>      create/register functionality.
>    - All previous callers of devm_fpga_mgr_register() will continue to call
>      devm_fpga_mgr_register().
>    - replaced unnecessary ternary operators in return statements with standard
>      if conditions.
> ---
>   drivers/fpga/altera-cvp.c        |  12 +--
>   drivers/fpga/altera-pr-ip-core.c |   8 +-
>   drivers/fpga/altera-ps-spi.c     |  10 +-
>   drivers/fpga/dfl-fme-mgr.c       |  10 +-
>   drivers/fpga/fpga-mgr.c          | 163 ++++++++-----------------------
>   drivers/fpga/ice40-spi.c         |  10 +-
>   drivers/fpga/machxo2-spi.c       |  10 +-
>   drivers/fpga/socfpga-a10.c       |  16 ++-
>   drivers/fpga/socfpga.c           |  10 +-
>   drivers/fpga/stratix10-soc.c     |  15 +--
>   drivers/fpga/ts73xx-fpga.c       |  10 +-
>   drivers/fpga/xilinx-spi.c        |  12 +--
>   drivers/fpga/zynq-fpga.c         |  16 ++-
>   drivers/fpga/zynqmp-fpga.c       |  10 +-
>   include/linux/fpga/fpga-mgr.h    |  17 ++--
>   15 files changed, 112 insertions(+), 217 deletions(-)
>
> diff --git a/drivers/fpga/altera-cvp.c b/drivers/fpga/altera-cvp.c
> index 4e0edb60bfba..b61020ceb0a1 100644
> --- a/drivers/fpga/altera-cvp.c
> +++ b/drivers/fpga/altera-cvp.c
> @@ -652,19 +652,15 @@ static int altera_cvp_probe(struct pci_dev *pdev,
>   	snprintf(conf->mgr_name, sizeof(conf->mgr_name), "%s @%s",
>   		 ALTERA_CVP_MGR_NAME, pci_name(pdev));
>   
> -	mgr = devm_fpga_mgr_create(&pdev->dev, conf->mgr_name,
> -				   &altera_cvp_ops, conf);
> -	if (!mgr) {
> -		ret = -ENOMEM;
> +	mgr = fpga_mgr_register(&pdev->dev, conf->mgr_name,
> +				&altera_cvp_ops, conf);
> +	if (IS_ERR(mgr)) {
> +		ret = PTR_ERR(mgr);
>   		goto err_unmap;
>   	}
>   
>   	pci_set_drvdata(pdev, mgr);

This is a wrapper around

dev_set_drvdata()

>   
> -	ret = fpga_mgr_register(mgr);
> -	if (ret)
> -		goto err_unmap;
> -
>   	return 0;
>   
>   err_unmap:
> diff --git a/drivers/fpga/altera-pr-ip-core.c b/drivers/fpga/altera-pr-ip-core.c
> index 5b130c4d9882..0980e134cc43 100644
> --- a/drivers/fpga/altera-pr-ip-core.c
> +++ b/drivers/fpga/altera-pr-ip-core.c
> @@ -191,11 +191,11 @@ int alt_pr_register(struct device *dev, void __iomem *reg_base)
>   		(val & ALT_PR_CSR_STATUS_MSK) >> ALT_PR_CSR_STATUS_SFT,
>   		(int)(val & ALT_PR_CSR_PR_START));
>   
> -	mgr = devm_fpga_mgr_create(dev, dev_name(dev), &alt_pr_ops, priv);
using the name of the device
> -	if (!mgr)
> -		return -ENOMEM;
> +	mgr = devm_fpga_mgr_register(dev, dev_name(dev), &alt_pr_ops, priv);
> +	if (IS_ERR(mgr))
> +		return PTR_ERR(mgr);
mgr is unused
>   
> -	return devm_fpga_mgr_register(dev, mgr);
> +	return 0;
>   }
>   EXPORT_SYMBOL_GPL(alt_pr_register);
>   
> diff --git a/drivers/fpga/altera-ps-spi.c b/drivers/fpga/altera-ps-spi.c
> index 23bfd4d1ad0f..d3f77b0312b2 100644
> --- a/drivers/fpga/altera-ps-spi.c
> +++ b/drivers/fpga/altera-ps-spi.c
> @@ -302,12 +302,12 @@ static int altera_ps_probe(struct spi_device *spi)
>   	snprintf(conf->mgr_name, sizeof(conf->mgr_name), "%s %s",
>   		 dev_driver_string(&spi->dev), dev_name(&spi->dev));
a combo of devices name, is that really necessary ?
>   
> -	mgr = devm_fpga_mgr_create(&spi->dev, conf->mgr_name,
> -				   &altera_ps_ops, conf);
> -	if (!mgr)
> -		return -ENOMEM;
> +	mgr = devm_fpga_mgr_register(&spi->dev, conf->mgr_name,
> +				     &altera_ps_ops, conf);
> +	if (IS_ERR(mgr))
> +		return PTR_ERR(mgr);
mgr is unused
>   
> -	return devm_fpga_mgr_register(&spi->dev, mgr);
> +	return 0;
>   }
>   
>   static const struct spi_device_id altera_ps_spi_ids[] = {
> diff --git a/drivers/fpga/dfl-fme-mgr.c b/drivers/fpga/dfl-fme-mgr.c
> index d5861d13b306..d71eba817b3b 100644
> --- a/drivers/fpga/dfl-fme-mgr.c
> +++ b/drivers/fpga/dfl-fme-mgr.c
> @@ -308,14 +308,14 @@ static int fme_mgr_probe(struct platform_device *pdev)
>   
>   	fme_mgr_get_compat_id(priv->ioaddr, compat_id);
>   
> -	mgr = devm_fpga_mgr_create(dev, "DFL FME FPGA Manager",
> -				   &fme_mgr_ops, priv);
> -	if (!mgr)
> -		return -ENOMEM;
> +	mgr = devm_fpga_mgr_register(dev, "DFL FME FPGA Manager",
> +				     &fme_mgr_ops, priv);
drv name is 'dfl-fme-mgr', is this close enough ?
> +	if (IS_ERR(mgr))
> +		return PTR_ERR(mgr);
>   
>   	mgr->compat_id = compat_id;
>   
> -	return devm_fpga_mgr_register(dev, mgr);
> +	return 0;
>   }
>   
>   static struct platform_driver fme_mgr_driver = {
> diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
> index b85bc47c91a9..22f0dd5c2834 100644
> --- a/drivers/fpga/fpga-mgr.c
> +++ b/drivers/fpga/fpga-mgr.c
> @@ -550,20 +550,20 @@ void fpga_mgr_unlock(struct fpga_manager *mgr)
>   EXPORT_SYMBOL_GPL(fpga_mgr_unlock);
>   
>   /**
> - * fpga_mgr_create - create and initialize a FPGA manager struct
> + * fpga_mgr_register - create and register a FPGA Manager device
>    * @dev:	fpga manager device from pdev

nit, space or tab after ':' ? this is inconsistent everywhere.


>    * @name:	fpga manager name
>    * @mops:	pointer to structure of fpga manager ops
>    * @priv:	fpga manager private data
>    *
> - * The caller of this function is responsible for freeing the struct with
> - * fpga_mgr_free().  Using devm_fpga_mgr_create() instead is recommended.
> + * The caller of this function is responsible for calling fpga_mgr_unregister().
> + * Using devm_fpga_mgr_register instead is recommended.
>    *
> - * Return: pointer to struct fpga_manager or NULL
> + * Returns a struct fpga_manager pointer on success, or ERR_PTR() on error.
>    */
> -struct fpga_manager *fpga_mgr_create(struct device *dev, const char *name,
> -				     const struct fpga_manager_ops *mops,
> -				     void *priv)
> +struct fpga_manager *
> +fpga_mgr_register(struct device *dev, const char *name,
> +		  const struct fpga_manager_ops *mops, void *priv)
>   {
>   	struct fpga_manager *mgr;
>   	int id, ret;
> @@ -572,21 +572,23 @@ struct fpga_manager *fpga_mgr_create(struct device *dev, const char *name,
>   	    !mops->write_init || (!mops->write && !mops->write_sg) ||
>   	    (mops->write && mops->write_sg)) {
>   		dev_err(dev, "Attempt to register without fpga_manager_ops\n");
> -		return NULL;
> +		return ERR_PTR(-EINVAL);

return -EINVAL;

And similar

The user's error checking is simplified to an int check.

The clunky ERR_PTR()/PTR_ERR() can be removed

>   	}
>   
>   	if (!name || !strlen(name)) {
>   		dev_err(dev, "Attempt to register with no name!\n");
> -		return NULL;
> +		return ERR_PTR(-EINVAL);
>   	}
>   
>   	mgr = kzalloc(sizeof(*mgr), GFP_KERNEL);
>   	if (!mgr)
> -		return NULL;
> +		return ERR_PTR(-ENOMEM);
>   
>   	id = ida_simple_get(&fpga_mgr_ida, 0, 0, GFP_KERNEL);
> -	if (id < 0)
> +	if (id < 0) {
> +		ret = id;
>   		goto error_kfree;
> +	}
>   
>   	mutex_init(&mgr->ref_mutex);
>   
> @@ -594,7 +596,6 @@ struct fpga_manager *fpga_mgr_create(struct device *dev, const char *name,

Just use the device name, do not give the user an option and simplify 
the calling parameters.

mgr->name = dev_name(dev)

>   	mgr->mops = mops;
>   	mgr->priv = priv;
>   
> -	device_initialize(&mgr->dev);
>   	mgr->dev.class = fpga_mgr_class;
>   	mgr->dev.groups = mops->groups;
>   	mgr->dev.parent = dev;
> @@ -605,84 +606,6 @@ struct fpga_manager *fpga_mgr_create(struct device *dev, const char *name,
>   	if (ret)
>   		goto error_device;
>   

The only use of returned mgr seems to be a variant of setting the 
dev->driver_data = mgr

so just make it the default and don't pass back the ptr.

dev_set_drvdata(dev, mgr);

return 0;


Tom