From bebf29b18f34620e25f7e2bd9e4e4d8e34a8977d Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= Date: Sun, 3 Nov 2024 17:03:31 +0000 Subject: [PATCH] sysfs: introduce callback attribute_group::bin_size MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Several drivers need to dynamically calculate the size of an binary attribute. Currently this is done by assigning attr->size from the is_bin_visible() callback. This has drawbacks: * It is not documented. * A single attribute can be instantiated multiple times, overwriting the shared size field. * It prevents the structure to be moved to read-only memory. Introduce a new dedicated callback to calculate the size of the attribute. Signed-off-by: Thomas Weißschuh Acked-by: Krzysztof Wilczyński Link: https://lore.kernel.org/r/20241103-sysfs-const-bin_attr-v2-2-71110628844c@weissschuh.net Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/group.c | 2 ++ include/linux/sysfs.h | 8 ++++++++ 2 files changed, 10 insertions(+) diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c index 45b2e92941da..8b01a7eda5fb 100644 --- a/fs/sysfs/group.c +++ b/fs/sysfs/group.c @@ -98,6 +98,8 @@ static int create_files(struct kernfs_node *parent, struct kobject *kobj, if (!mode) continue; } + if (grp->bin_size) + size = grp->bin_size(kobj, *bin_attr, i); WARN(mode & ~(SYSFS_PREALLOC | 0664), "Attribute %s: Invalid permissions 0%o\n", diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h index c4e64dc11206..4746cccb9589 100644 --- a/include/linux/sysfs.h +++ b/include/linux/sysfs.h @@ -87,6 +87,11 @@ do { \ * SYSFS_GROUP_VISIBLE() when assigning this callback to * specify separate _group_visible() and _attr_visible() * handlers. + * @bin_size: + * Optional: Function to return the size of a binary attribute + * of the group. Will be called repeatedly for each binary + * attribute in the group. Overwrites the size field embedded + * inside the attribute itself. * @attrs: Pointer to NULL terminated list of attributes. * @bin_attrs: Pointer to NULL terminated list of binary attributes. * Either attrs or bin_attrs or both must be provided. @@ -97,6 +102,9 @@ struct attribute_group { struct attribute *, int); umode_t (*is_bin_visible)(struct kobject *, struct bin_attribute *, int); + size_t (*bin_size)(struct kobject *, + const struct bin_attribute *, + int); struct attribute **attrs; struct bin_attribute **bin_attrs; };