On Sun, Jun 30, 2024 at 09:49:00PM +0200, Lukas Wunner wrote: > A subsequent commit has the need to create a symlink from an attribute > in a first group to an attribute in a second group. Both groups belong > to the same kobject. > > More specifically, each signature received from an authentication- > capable device is going to be represented by a file in the first group > and shall be accompanied by a symlink pointing to the certificate slot > in the second group which was used to generate the signature (a device > may have multiple certificate slots and each is represented by a > separate file in the second group): > > /sys/devices/.../signatures/0_certificate_chain -> .../certificates/slot0 > > There is already a sysfs_add_link_to_group() helper to add a symlink to > a group which points to another kobject, but this isn't what's needed > here. > > So add a new function to add a symlink among sibling groups of the same > kobject. > > The existing sysfs_add_link_to_group() helper goes through a locking > dance of acquiring sysfs_symlink_target_lock in order to acquire a > reference on the target kobject. That's unnecessary for the present > use case as the link itself and its target reside below the same > kobject. > > To simplify error handling in the newly introduced function, add a > DEFINE_FREE() clause for kernfs_put(). Nice! > > Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx> Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
