Messages in this thread | | | Date | Mon, 10 Sep 2007 13:51:59 +0200 | From | Cornelia Huck <> | Subject | Re: regarding sysfs/kobject separation |
| |
On Sun, 02 Sep 2007 22:40:58 +0900, Tejun Heo <htejun@gmail.com> wrote:
> * Suicidal nodes don't need special treatment. If a file tries to > commit suicide, sysfs will detect the condition and deactivate and drain > the node except for the suiciding reference.
Excellent. This is so easy to overlook.
> * Plugged creation and batched error handling. Sysfs directories can be > 'plugged' on creation such that it can be made visible atomically after > all its subtrees are constructed. Also, the user doesn't have to check > for failure at every step. For example, the user can do the following. > > dir = sysfs_add_dir(parent, "my_dir", SYSFS_PLUGGED | 0777); > sysfs_add_file(dir, ...); > ... > dir2 = sysfs_add_dir(dir, ...); > sysfs_add_link(dir, "link-to-dir2", dir2); > ... > if (sysfs_check_batch_error(dir) == 0) > sysfs_unplug(dir); > else > sysfs_remove(dir); > > And all the nodes under and including @dir will show up atomically if > all operations succeeded or removed without ever bothering userland.
Hm. This sounds like two different things:
- Eliminate the need to check after each operation. Might be a matter of taste; personally, I prefer checking and unwinding on error.
- Atomic creation/deletion of a bunch of sysfs nodes. This sounds like something really worthwile to have.
> > * Automatic symlink handling. Symlink names can be formatted with the > name of its target. e.g. if the symlink name is specified as > "link-%1:%0" and points to "devices/mybus0/mydev0", its name becomes > "link-mybus0-mydev0" && the symlink will be automatically renamed when > the target node or one of its ancestor is moved or renamed. The symlink > is also plugged and removed together with its target. So, once created, > the user doesn't have to care about the symlink. sysfs will take care > of it.
Really nice. The need to delete/create symlinks on moving/renaming is currently a headache inducer.
> * Move uevent support over to sysfs and bridging the current users. > This makes sense because sysfs hierarchy is all that userland can see > and sysfs users which don't use kobject also needs uevent support.
Makes sense.
> > * Convert device model (drivers/base/*) over to the new sysfs_dirent > based interface and make device/driver <-> sysfs association flexible. > Automatic sysfs association is a good thing. In most cases, it makes > sense and makes drivers simpler but it also needs to be flexible such > that drivers with special needs can override how the device and driver > are represented to userland. I think such flexibility can be achieved > without too much problem now that sysfs and kobject are separated.
Yes, if we can change internal implementation details without upsetting userspace a lot is gained. As long as the default behaviour remains easy to implement. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |