Re: [PATCH v1 01/12] PCI: hotplug: add new callbacks on hotplug_slot_ops

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Jan 18, 2023 at 08:35:51PM -0500, Tianfei Zhang wrote:
> To reprogram an PCIe-based FPGA card, a new image is
> burned into FLASH on the card and then the card BMC is
> triggered to reboot the card and load the new image.
> 
> Two new operation callbacks are defined in hotplug_slot_ops
> to trigger the reprogramming of an FPGA-based PCIe card:
> 
>   - available_images: Optional: available FPGA images
>   - image_load: Optional: trigger the FPGA to load a new image
> 
> Signed-off-by: Tianfei Zhang <tianfei.zhang@intel.com>
> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> ---
>  drivers/pci/hotplug/pci_hotplug_core.c | 88 ++++++++++++++++++++++++++
>  include/linux/pci_hotplug.h            |  5 ++
>  2 files changed, 93 insertions(+)
> 
> diff --git a/drivers/pci/hotplug/pci_hotplug_core.c b/drivers/pci/hotplug/pci_hotplug_core.c
> index 058d5937d8a9..2b14b6513a03 100644
> --- a/drivers/pci/hotplug/pci_hotplug_core.c
> +++ b/drivers/pci/hotplug/pci_hotplug_core.c
> @@ -231,6 +231,52 @@ static struct pci_slot_attribute hotplug_slot_attr_test = {
>  	.store = test_write_file
>  };
>  
> +static ssize_t available_images_read_file(struct pci_slot *pci_slot, char *buf)
> +{
> +	struct hotplug_slot *slot = pci_slot->hotplug;
> +	ssize_t count = 0;
> +
> +	if (!try_module_get(slot->owner))
> +		return -ENODEV;
> +
> +	if (slot->ops->available_images(slot, buf))
> +		count = slot->ops->available_images(slot, buf);
> +
> +	module_put(slot->owner);
> +
> +	return count;
> +}
> +
> +static struct pci_slot_attribute hotplug_slot_attr_available_images = {
> +	.attr = { .name = "available_images", .mode = 0444 },
> +	.show = available_images_read_file,

If you name things properly, you can use the correct macros and not have
to open-code any of this :(

> +static ssize_t image_load_write_file(struct pci_slot *pci_slot,
> +				     const char *buf, size_t count)
> +{
> +	struct hotplug_slot *slot = pci_slot->hotplug;
> +	int retval = 0;
> +
> +	if (!try_module_get(slot->owner))
> +		return -ENODEV;
> +
> +	if (slot->ops->image_load)
> +		retval = slot->ops->image_load(slot, buf);
> +
> +	module_put(slot->owner);
> +
> +	if (retval)
> +		return retval;
> +
> +	return count;
> +}
> +
> +static struct pci_slot_attribute hotplug_slot_attr_image_load = {
> +	.attr = { .name = "image_load", .mode = 0644 },
> +	.store = image_load_write_file,

Same here, don't open-code this.

> +};
> +
>  static bool has_power_file(struct pci_slot *pci_slot)
>  {
>  	struct hotplug_slot *slot = pci_slot->hotplug;
> @@ -289,6 +335,20 @@ static bool has_test_file(struct pci_slot *pci_slot)
>  	return false;
>  }
>  
> +static bool has_available_images_file(struct pci_slot *pci_slot)
> +{
> +	struct hotplug_slot *slot = pci_slot->hotplug;
> +
> +	return slot && slot->ops && slot->ops->available_images;
> +}
> +
> +static bool has_image_load_file(struct pci_slot *pci_slot)
> +{
> +	struct hotplug_slot *slot = pci_slot->hotplug;
> +
> +	return slot && slot->ops && slot->ops->image_load;
> +}
> +
>  static int fs_add_slot(struct pci_slot *pci_slot)
>  {
>  	int retval = 0;
> @@ -331,8 +391,30 @@ static int fs_add_slot(struct pci_slot *pci_slot)
>  			goto exit_test;
>  	}
>  
> +	if (has_available_images_file(pci_slot)) {
> +		retval = sysfs_create_file(&pci_slot->kobj,
> +					   &hotplug_slot_attr_available_images.attr);
> +		if (retval)
> +			goto exit_available_images;
> +	}
> +
> +	if (has_image_load_file(pci_slot)) {
> +		retval = sysfs_create_file(&pci_slot->kobj,
> +					   &hotplug_slot_attr_image_load.attr);
> +		if (retval)
> +			goto exit_image_load;
> +	}
> +
>  	goto exit;
>  
> +exit_image_load:
> +	if (has_adapter_file(pci_slot))
> +		sysfs_remove_file(&pci_slot->kobj,
> +				  &hotplug_slot_attr_available_images.attr);
> +exit_available_images:
> +	if (has_adapter_file(pci_slot))
> +		sysfs_remove_file(&pci_slot->kobj,
> +				  &hotplug_slot_attr_test.attr);
>  exit_test:
>  	if (has_adapter_file(pci_slot))
>  		sysfs_remove_file(&pci_slot->kobj,
> @@ -372,6 +454,12 @@ static void fs_remove_slot(struct pci_slot *pci_slot)
>  	if (has_test_file(pci_slot))
>  		sysfs_remove_file(&pci_slot->kobj, &hotplug_slot_attr_test.attr);
>  
> +	if (has_available_images_file(pci_slot))
> +		sysfs_remove_file(&pci_slot->kobj, &hotplug_slot_attr_available_images.attr);
> +
> +	if (has_image_load_file(pci_slot))
> +		sysfs_remove_file(&pci_slot->kobj, &hotplug_slot_attr_image_load.attr);
> +

Ick no, please just make this an attribute group that properly shows or
does not show, the attribute when created.  Do not manually add
individual sysfs files.

Yes, I know the existing code does this, so it's not really your fault,
but let's not persist in making this code even messier.  Convert to a
group first and then your new files will be added automagically without
having to care about anything here at all.

thanks,

greg k-h