Hi,
在 2024/07/12 2:03, Bart Van Assche 写道:
On 7/11/24 2:00 AM, Yu Kuai wrote:
ioprio works on the blk-cgroup level, all disks in the same cgroup
are the same, and the struct ioprio_blkg doesn't have anything in it.
Hence register the policy is enough, because cpd_alloc/free_fn will
be handled for each blk-cgroup, and there is no need to activate the
policy for disk.
As one can see in the output of git grep -nHEB1 '>pd_(alloc|free)_fn\(',
none of the pd_alloc_fn / pd_free_fn callers checks whether or not these
pointers are NULL. Hence my question why this patch does not trigger any
NULL pointer dereferences?
Because the blkcg_deactivate_policy() is removed as well, there are no
callers now... blkcg_policy_register() is still called to make sure
cpd_(alloc|free)_fn will still be called.
Thanks,
Kuai
Thanks,
Bart.
.
