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| author | Thomas Weißschuh <linux@weissschuh.net> | 2024-11-03 17:03:31 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-11-05 14:00:28 +0100 |
| commit | bebf29b18f34620e25f7e2bd9e4e4d8e34a8977d (patch) | |
| tree | c18a29612d16c0c23471702f3023e093c1f9c100 | |
| parent | 0afcee132bbc9d7ef9c5bb4da9b6fe014a9afaa9 (diff) | |
| download | lwn-bebf29b18f34620e25f7e2bd9e4e4d8e34a8977d.tar.gz lwn-bebf29b18f34620e25f7e2bd9e4e4d8e34a8977d.zip | |
sysfs: introduce callback attribute_group::bin_size
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 <linux@weissschuh.net>
Acked-by: Krzysztof Wilczyński <kw@linux.com>
Link: https://lore.kernel.org/r/20241103-sysfs-const-bin_attr-v2-2-71110628844c@weissschuh.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/sysfs/group.c | 2 | ||||
| -rw-r--r-- | include/linux/sysfs.h | 8 |
2 files changed, 10 insertions, 0 deletions
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; }; |