firmware: arm_scmi: Fix SCMI device destroy lifetimes

scmi_child_dev_find() drops the reference returned by
device_find_child() before returning the scmi_device pointer. A
concurrent unregister can then release the device while the destroy path
is still using the returned pointer.

Make the lookup helper return the device_find_child() reference and keep
it until scmi_device_destroy() has finished unregistering the child.

Also split device_unregister() in __scmi_device_destroy() so the SCMI bus
ID is not made reusable until after device_del() has removed the old
scmi_dev.N name from sysfs. This avoids a new SCMI device reusing the
same ID while the old device is still registered.

The final device release callback is also a possible cleanup path when
SCMI children are deleted by driver core recursion rather than
__scmi_device_destroy(). Release the SCMI bus ID from a common helper
used by destroy, register-failure and final-release paths, and clear
scmi_dev->id after freeing it so the final release cannot free the same
ID again.

Fixes: 9ca67840c0dd ("firmware: arm_scmi: Balance device refcount when destroying devices")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Link: https://patch.msgid.link/20260714-scmi_core_fixes-v6-15-3afe499d46e3@kernel.org
Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org>

0 files changed, 0 insertions, 0 deletions