Subject: Re: [PATCH 2/2] treewide: Use sysfs_bin_attr_simple_read() helper

From: Zhi Wang <[email-masked]>
Date: Mon, 8 Apr 2024 13:42:22 +0300

On Sat, 6 Apr 2024 15:52:02 +0200
Lukas Wunner <[email-masked]> wrote:

> Deduplicate ->read() callbacks of bin_attributes which are backed by a
> simple buffer in memory:
> 
> Use the newly introduced sysfs_bin_attr_simple_read() helper instead,
> either by referencing it directly or by declaring such bin_attributes
> with BIN_ATTR_SIMPLE_RO() or BIN_ATTR_SIMPLE_ADMIN_RO().
> 
> Aside from a reduction of LoC, this shaves off a few bytes from
> vmlinux (304 bytes on an x86_64 allyesconfig).
> 
> No functional change intended.
> 

As for GVT, looks good to me.

Acked-by: Zhi Wang <[email-masked]>

> Signed-off-by: Lukas Wunner <[email-masked]>
> ---
>  arch/powerpc/platforms/powernv/opal.c              | 10 +--------
>  drivers/acpi/bgrt.c                                |  9 +-------
>  drivers/firmware/dmi_scan.c                        | 12 ++--------
>  drivers/firmware/efi/rci2-table.c                  | 10 +--------
>  drivers/gpu/drm/i915/gvt/firmware.c                | 26
> +++++----------------- .../intel/int340x_thermal/int3400_thermal.c
>     |  9 +------- init/initramfs.c
> | 10 +-------- kernel/module/sysfs.c                              |
> 13 +---------- 8 files changed, 14 insertions(+), 85 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/powernv/opal.c
> b/arch/powerpc/platforms/powernv/opal.c index 45dd77e..5d0f35b 100644
> --- a/arch/powerpc/platforms/powernv/opal.c
> +++ b/arch/powerpc/platforms/powernv/opal.c
> @@ -792,14 +792,6 @@ static int __init opal_sysfs_init(void)
>  	return 0;
>  }
>  
> -static ssize_t export_attr_read(struct file *fp, struct kobject
> *kobj,
> -				struct bin_attribute *bin_attr, char
> *buf,
> -				loff_t off, size_t count)
> -{
> -	return memory_read_from_buffer(buf, count, &off,
> bin_attr->private,
> -				       bin_attr->size);
> -}
> -
>  static int opal_add_one_export(struct kobject *parent, const char
> *export_name, struct device_node *np, const char *prop_name)
>  {
> @@ -826,7 +818,7 @@ static int opal_add_one_export(struct kobject
> *parent, const char *export_name, sysfs_bin_attr_init(attr);
>  	attr->attr.name = name;
>  	attr->attr.mode = 0400;
> -	attr->read = export_attr_read;
> +	attr->read = sysfs_bin_attr_simple_read;
>  	attr->private = __va(vals[0]);
>  	attr->size = vals[1];
>  
> diff --git a/drivers/acpi/bgrt.c b/drivers/acpi/bgrt.c
> index e4fb9e2..d1d9c92 100644
> --- a/drivers/acpi/bgrt.c
> +++ b/drivers/acpi/bgrt.c
> @@ -29,14 +29,7 @@
>  BGRT_SHOW(xoffset, image_offset_x);
>  BGRT_SHOW(yoffset, image_offset_y);
>  
> -static ssize_t image_read(struct file *file, struct kobject *kobj,
> -	       struct bin_attribute *attr, char *buf, loff_t off,
> size_t count) -{
> -	memcpy(buf, attr->private + off, count);
> -	return count;
> -}
> -
> -static BIN_ATTR_RO(image, 0);	/* size gets filled in later */
> +static BIN_ATTR_SIMPLE_RO(image);
>  
>  static struct attribute *bgrt_attributes[] = {
>  	&bgrt_attr_version.attr,
> diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
> index 015c95a..3d0f773 100644
> --- a/drivers/firmware/dmi_scan.c
> +++ b/drivers/firmware/dmi_scan.c
> @@ -746,16 +746,8 @@ static void __init dmi_scan_machine(void)
>  	pr_info("DMI not present or invalid.\n");
>  }
>  
> -static ssize_t raw_table_read(struct file *file, struct kobject
> *kobj,
> -			      struct bin_attribute *attr, char *buf,
> -			      loff_t pos, size_t count)
> -{
> -	memcpy(buf, attr->private + pos, count);
> -	return count;
> -}
> -
> -static BIN_ATTR(smbios_entry_point, S_IRUSR, raw_table_read, NULL,
> 0); -static BIN_ATTR(DMI, S_IRUSR, raw_table_read, NULL, 0);
> +static BIN_ATTR_SIMPLE_ADMIN_RO(smbios_entry_point);
> +static BIN_ATTR_SIMPLE_ADMIN_RO(DMI);
>  
>  static int __init dmi_init(void)
>  {
> diff --git a/drivers/firmware/efi/rci2-table.c
> b/drivers/firmware/efi/rci2-table.c index de1a9a1..4fd45d6 100644
> --- a/drivers/firmware/efi/rci2-table.c
> +++ b/drivers/firmware/efi/rci2-table.c
> @@ -40,15 +40,7 @@ struct rci2_table_global_hdr {
>  static u32 rci2_table_len;
>  unsigned long rci2_table_phys __ro_after_init =
> EFI_INVALID_TABLE_ADDR; 
> -static ssize_t raw_table_read(struct file *file, struct kobject
> *kobj,
> -			      struct bin_attribute *attr, char *buf,
> -			      loff_t pos, size_t count)
> -{
> -	memcpy(buf, attr->private + pos, count);
> -	return count;
> -}
> -
> -static BIN_ATTR(rci2, S_IRUSR, raw_table_read, NULL, 0);
> +static BIN_ATTR_SIMPLE_ADMIN_RO(rci2);
>  
>  static u16 checksum(void)
>  {
> diff --git a/drivers/gpu/drm/i915/gvt/firmware.c
> b/drivers/gpu/drm/i915/gvt/firmware.c index 4dd52ac..5e66a26 100644
> --- a/drivers/gpu/drm/i915/gvt/firmware.c
> +++ b/drivers/gpu/drm/i915/gvt/firmware.c
> @@ -50,21 +50,7 @@ struct gvt_firmware_header {
>  
>  #define dev_to_drm_minor(d) dev_get_drvdata((d))
>  
> -static ssize_t
> -gvt_firmware_read(struct file *filp, struct kobject *kobj,
> -	     struct bin_attribute *attr, char *buf,
> -	     loff_t offset, size_t count)
> -{
> -	memcpy(buf, attr->private + offset, count);
> -	return count;
> -}
> -
> -static struct bin_attribute firmware_attr = {
> -	.attr = {.name = "gvt_firmware", .mode = (S_IRUSR)},
> -	.read = gvt_firmware_read,
> -	.write = NULL,
> -	.mmap = NULL,
> -};
> +static BIN_ATTR_SIMPLE_ADMIN_RO(gvt_firmware);
>  
>  static int expose_firmware_sysfs(struct intel_gvt *gvt)
>  {
> @@ -107,10 +93,10 @@ static int expose_firmware_sysfs(struct
> intel_gvt *gvt) crc32_start = offsetof(struct gvt_firmware_header,
> version); h->crc32 = crc32_le(0, firmware + crc32_start, size -
> crc32_start); 
> -	firmware_attr.size = size;
> -	firmware_attr.private = firmware;
> +	bin_attr_gvt_firmware.size = size;
> +	bin_attr_gvt_firmware.private = firmware;
>  
> -	ret = device_create_bin_file(&pdev->dev, &firmware_attr);
> +	ret = device_create_bin_file(&pdev->dev,
> &bin_attr_gvt_firmware); if (ret) {
>  		vfree(firmware);
>  		return ret;
> @@ -122,8 +108,8 @@ static void clean_firmware_sysfs(struct intel_gvt
> *gvt) {
>  	struct pci_dev *pdev = to_pci_dev(gvt->gt->i915->drm.dev);
>  
> -	device_remove_bin_file(&pdev->dev, &firmware_attr);
> -	vfree(firmware_attr.private);
> +	device_remove_bin_file(&pdev->dev, &bin_attr_gvt_firmware);
> +	vfree(bin_attr_gvt_firmware.private);
>  }
>  
>  /**
> diff --git a/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
> b/drivers/thermal/intel/int340x_thermal/int3400_thermal.c index
> 427d370..6d4b51a 100644 ---
> a/drivers/thermal/intel/int340x_thermal/int3400_thermal.c +++
> b/drivers/thermal/intel/int340x_thermal/int3400_thermal.c @@ -73,14
> +73,7 @@ struct odvp_attr { struct device_attribute attr;
>  };
>  
> -static ssize_t data_vault_read(struct file *file, struct kobject
> *kobj,
> -	     struct bin_attribute *attr, char *buf, loff_t off,
> size_t count) -{
> -	memcpy(buf, attr->private + off, count);
> -	return count;
> -}
> -
> -static BIN_ATTR_RO(data_vault, 0);
> +static BIN_ATTR_SIMPLE_RO(data_vault);
>  
>  static struct bin_attribute *data_attributes[] = {
>  	&bin_attr_data_vault,
> diff --git a/init/initramfs.c b/init/initramfs.c
> index da79760..5193fae 100644
> --- a/init/initramfs.c
> +++ b/init/initramfs.c
> @@ -575,15 +575,7 @@ static int __init initramfs_async_setup(char
> *str) #include <linux/initrd.h>
>  #include <linux/kexec.h>
>  
> -static ssize_t raw_read(struct file *file, struct kobject *kobj,
> -			struct bin_attribute *attr, char *buf,
> -			loff_t pos, size_t count)
> -{
> -	memcpy(buf, attr->private + pos, count);
> -	return count;
> -}
> -
> -static BIN_ATTR(initrd, 0440, raw_read, NULL, 0);
> +static BIN_ATTR(initrd, 0440, sysfs_bin_attr_simple_read, NULL, 0);
>  
>  void __init reserve_initrd_mem(void)
>  {
> diff --git a/kernel/module/sysfs.c b/kernel/module/sysfs.c
> index d964167..26efe13 100644
> --- a/kernel/module/sysfs.c
> +++ b/kernel/module/sysfs.c
> @@ -146,17 +146,6 @@ struct module_notes_attrs {
>  	struct bin_attribute attrs[] __counted_by(notes);
>  };
>  
> -static ssize_t module_notes_read(struct file *filp, struct kobject
> *kobj,
> -				 struct bin_attribute *bin_attr,
> -				 char *buf, loff_t pos, size_t count)
> -{
> -	/*
> -	 * The caller checked the pos and count against our size.
> -	 */
> -	memcpy(buf, bin_attr->private + pos, count);
> -	return count;
> -}
> -
>  static void free_notes_attrs(struct module_notes_attrs *notes_attrs,
>  			     unsigned int i)
>  {
> @@ -205,7 +194,7 @@ static void add_notes_attrs(struct module *mod,
> const struct load_info *info) nattr->attr.mode = 0444;
>  			nattr->size = info->sechdrs[i].sh_size;
>  			nattr->private = (void
> *)info->sechdrs[i].sh_addr;
> -			nattr->read = module_notes_read;
> +			nattr->read = sysfs_bin_attr_simple_read;
>  			++nattr;
>  		}
>  		++loaded;