On Sat, Apr 27, 2024 at 02:33:24PM -0700, Dan Williams wrote: > Lukas Wunner wrote: > > Perhaps an optional ->is_group_visible() callback in struct attribute_group > > which gets passed only the struct kobject pointer? > > > > At least for PCI device authentication, that would be sufficient. > > I could get from the kobject to the corresponding struct device, > > then determine whether the device supports authentication or not. > > > > Because it's a new, optional callback, there should be no compatibility > > issues. The SYSFS_GROUP_INVISIBLE return code from the ->is_visible() > > call for individual attributes would not be needed then, at least in my > > use case. > > That's where I started with this, but decided it was overkill to > increase the size of that data structure globally for a small number of > use cases. Memory is cheap and memory-constrained devices can set CONFIG_SYSFS=n. There aren't that many struct attribute_groups and this is just 8 additional bytes on a 64-bit machine. (There are way more struct attribute than struct attribute_group.) The contortions necessary to overload individual attribute ->is_visible() callbacks to also govern the group's visibility aren't worth it. Having an ->is_group_visible() callback has the additional benefit that the mode of directories no longer needs to be hardcoded to 0755 in sysfs_create_dir_ns(), but can be set to, say, 0500 or 0700 or 0511, depending on the use case. So more flexibility there as well. Thanks, Lukas
