kernel/linux.git/include/linux/sysfs.h, branch v6.19.11

sysfs: simplify attribute definition macros

2025-11-26T14:16:35+00:00

Define the macros in terms of each other. This makes them easier to understand and also will make it easier to implement the transition machinery for 'const struct attribute'. __ATTR_RO_MODE() can't be implemented in terms of __ATTR() as not all attributes have a .store callback. The same issue theoretically exists for __ATTR_WO(), but practically that does not occur today. Reorder __ATTR_RO() below __ATTR_RO_MODE() to keep the order of the macro definition consistent with respect to each other. Signed-off-by: Thomas Weißschuh Link: https://patch.msgid.link/20251029-sysfs-const-attr-prep-v5-7-ea7d745acff4@weissschuh.net Signed-off-by: Greg Kroah-Hartman

sysfs: attribute_group: enable const variants of is_visible()

2025-11-26T14:16:35+00:00

When constifying instances of struct attribute, for consistency the corresponding .is_visible() callback should be adapted, too. Introduce a temporary transition mechanism until all callbacks are converted. Signed-off-by: Thomas Weißschuh Link: https://patch.msgid.link/20251029-sysfs-const-attr-prep-v5-4-ea7d745acff4@weissschuh.net Signed-off-by: Greg Kroah-Hartman

sysfs: introduce __SYSFS_FUNCTION_ALTERNATIVE()

2025-11-26T14:16:35+00:00

For the constification phase of 'struct attribute' various callback struct members will need to exist in both const and non-const variants. Keeping both members in a union avoids memory and CPU overhead but will be detected and trapped by Control Flow Integrity (CFI). By deciding between a struct and a union depending whether CFI is enabled, most configurations can avoid this overhead. Code using these callbacks will still need to be updated to handle both members explicitly. In the union case the compiler will recognize that testing for one union member is enough and optimize away the code for the other one. Signed-off-by: Thomas Weißschuh Link: https://patch.msgid.link/20251029-sysfs-const-attr-prep-v5-3-ea7d745acff4@weissschuh.net Signed-off-by: Greg Kroah-Hartman

sysfs: transparently handle const pointers in ATTRIBUTE_GROUPS()

2025-11-26T14:16:35+00:00

To ease the constification process of 'struct attribute', transparently handle the const pointers in ATTRIBUTE_GROUPS(). A cast is used instead of assigning to .attrs_new as it keeps the macro smaller. As both members are aliased to each other the result is identical. Signed-off-by: Thomas Weißschuh Link: https://patch.msgid.link/20251029-sysfs-const-attr-prep-v5-2-ea7d745acff4@weissschuh.net Signed-off-by: Greg Kroah-Hartman

sysfs: attribute_group: allow registration of const attribute

2025-11-26T14:16:34+00:00

To be able to constify instances of struct attribute it has to be possible to add them to struct attribute_group. The current type of the attrs member however is not compatible with that. Introduce a union that allows registration of both const and non-const attributes to enable a piecewise transition. As both union member types are compatible no logic needs to be adapted. Technically it is now possible register a const struct attribute and receive it as mutable pointer in the callbacks. This is a soundness issue. But this same soundness issue already exists today in sysfs_create_file(). Also the struct definition and callback implementation are always closely linked and are meant to be moved to const in lockstep. Similar to commit 906c508afdca ("sysfs: attribute_group: allow registration of const bin_attribute") Signed-off-by: Thomas Weißschuh Link: https://patch.msgid.link/20251029-sysfs-const-attr-prep-v5-1-ea7d745acff4@weissschuh.net Signed-off-by: Greg Kroah-Hartman

sysfs: remove attribute_group::bin_attrs_new

2025-08-19T11:12:12+00:00

This transitional field is now unused and unnecessary. Remove it. Signed-off-by: Thomas Weißschuh Link: https://lore.kernel.org/r/20250811-sysfs-const-bin_attr-final-v4-2-7b6053fd58bb@weissschuh.net Signed-off-by: Greg Kroah-Hartman

sysfs: remove bin_attribute::read_new/write_new()

2025-08-19T11:12:12+00:00

These transitional fields are now unused and unnecessary. Remove them and their logic in the sysfs core. Signed-off-by: Thomas Weißschuh Link: https://lore.kernel.org/r/20250811-sysfs-const-bin_attr-final-v4-1-7b6053fd58bb@weissschuh.net Signed-off-by: Greg Kroah-Hartman

sysfs: constify attribute_group::bin_attrs

2025-04-15T16:46:10+00:00

All users of this field have been migrated to bin_attrs_new. It can now be constified. Signed-off-by: Thomas Weißschuh Link: https://lore.kernel.org/r/20250313-sysfs-const-bin_attr-final-v2-2-96284e1e88ce@weissschuh.net Signed-off-by: Greg Kroah-Hartman

sysfs: constify bin_attribute argument of bin_attribute::read/write()

2025-04-15T16:45:32+00:00

All callback implementers have been moved to the const variant of the callbacks. The signature of the original callbacks can now be changed. Also remove the now unnecessary transition machinery inside __BIN_ATTR(). Signed-off-by: Thomas Weißschuh Link: https://lore.kernel.org/r/20250313-sysfs-const-bin_attr-final-v2-1-96284e1e88ce@weissschuh.net Signed-off-by: Greg Kroah-Hartman

sysfs: constify bin_attribute argument of sysfs_bin_attr_simple_read()

2025-01-09T09:43:58+00:00

Most users use this function through the BIN_ATTR_SIMPLE* macros, they can handle the switch transparently. Also adapt the two non-macro users in the same change. Signed-off-by: Thomas Weißschuh Acked-by: Madhavan Srinivasan Reviewed-by: Mahesh Salgaonkar Tested-by: Aditya Gupta Link: https://lore.kernel.org/r/20241228-sysfs-const-bin_attr-simple-v2-1-7c6f3f1767a3@weissschuh.net Signed-off-by: Greg Kroah-Hartman